8214971: Replace use of string.equals("") with isEmpty()

Reviewed-by: jlaskey, prappo, lancea, dfuchs, redestad

src/java.base/share/classes/com/sun/java/util/jar/pack/ConstantPool.java

@@ -1366,7 +1366,7 @@ class ConstantPool {
             }
             if (tag == CONSTANT_Utf8) {
                 // Special case:  First Utf8 must always be empty string.
-                assert(cpMap.length == 0 || cpMap[0].stringValue().equals(""));
+                assert(cpMap.length == 0 || cpMap[0].stringValue().isEmpty());
             }
             indexByTag[tag] = ix;
             // decache indexes derived from this one:

src/java.base/share/classes/com/sun/java/util/jar/pack/Driver.java

@@ -208,7 +208,7 @@ class Driver {
             }
         }
 
-        if (logFile != null && !logFile.equals("")) {
+        if (logFile != null && !logFile.isEmpty()) {
             if (logFile.equals("-")) {
                 System.setErr(System.out);
             } else {
@@ -246,7 +246,7 @@ class Driver {
             }
             newfile = packfile;
             // The optional second argument is the source JAR file.
-            if (jarfile.equals("")) {
+            if (jarfile.isEmpty()) {
                 // If only one file is given, it is the only JAR.
                 // It serves as both input and output.
                 jarfile = newfile;
@@ -352,7 +352,7 @@ class Driver {
                 if (Utils.isGZIPMagic(Utils.readMagic(inBuf))) {
                     in = new GZIPInputStream(in);
                 }
-                String outfile = newfile.equals("")? jarfile: newfile;
+                String outfile = newfile.isEmpty()? jarfile: newfile;
                 OutputStream fileOut;
                 if (outfile.equals("-"))
                     fileOut = System.out;
@@ -366,7 +366,7 @@ class Driver {
                 // At this point, we have a good jarfile (or newfile, if -r)
             }
 
-            if (!bakfile.equals("")) {
+            if (!bakfile.isEmpty()) {
                         // On success, abort jarfile recovery bracket.
                         new File(bakfile).delete();
                         bakfile = "";
@@ -374,13 +374,13 @@ class Driver {
 
         } finally {
             // Close jarfile recovery bracket.
-            if (!bakfile.equals("")) {
+            if (!bakfile.isEmpty()) {
                 File jarFile = new File(jarfile);
                 jarFile.delete(); // Win32 requires this, see above
                 new File(bakfile).renameTo(jarFile);
             }
             // In all cases, delete temporary *.pack.
-            if (!tmpfile.equals(""))
+            if (!tmpfile.isEmpty())
                 new File(tmpfile).delete();
         }
     }

src/java.base/share/classes/com/sun/java/util/jar/pack/Package.java

@@ -685,7 +685,7 @@ class Package {
                 return;  // do not choose yet
             }
             String canonName = canonicalFileName();
-            if (file.nameString.equals("")) {
+            if (file.nameString.isEmpty()) {
                 file.nameString = canonName;
             }
             if (file.nameString.equals(canonName)) {
@@ -706,7 +706,7 @@ class Package {
 
         public java.io.File getFileName(java.io.File parent) {
             String name = file.name.stringValue();
-            if (name.equals(""))
+            if (name.isEmpty())
                 name = canonicalFileName();
             String fname = name.replace('/', java.io.File.separatorChar);
             return new java.io.File(parent, fname);
@@ -779,7 +779,7 @@ class Package {
         }
         public boolean isTrivialClassStub() {
             return isClassStub()
-                && name.stringValue().equals("")
+                && name.stringValue().isEmpty()
                 && (modtime == NO_MODTIME || modtime == default_modtime)
                 && (options &~ FO_IS_CLASS_STUB) == 0;
         }

src/java.base/share/classes/com/sun/java/util/jar/pack/PackageWriter.java

@@ -646,7 +646,7 @@ class PackageWriter extends BandStructure {
             return;  // nothing to write
 
         // The first element must always be the empty string.
-        assert(cpMap[0].stringValue().equals(""));
+        assert(cpMap[0].stringValue().isEmpty());
         final int SUFFIX_SKIP_1 = 1;
         final int PREFIX_SKIP_2 = 2;
 

src/java.base/share/classes/com/sun/java/util/jar/pack/PackerImpl.java

@@ -237,7 +237,7 @@ public class PackerImpl  extends TLGlobals implements Pack200.Packer {
         final long segmentLimit;
         {
             long limit;
-            if (props.getProperty(Pack200.Packer.SEGMENT_LIMIT, "").equals(""))
+            if (props.getProperty(Pack200.Packer.SEGMENT_LIMIT, "").isEmpty())
                 limit = -1;
             else
                 limit = props.getLong(Pack200.Packer.SEGMENT_LIMIT);

src/java.base/share/classes/java/io/File.java

@@ -257,7 +257,7 @@ public class File
      */
     private File(String child, File parent) {
         assert parent.path != null;
-        assert (!parent.path.equals(""));
+        assert (!parent.path.isEmpty());
         this.path = fs.resolve(parent.path, child);
         this.prefixLength = parent.prefixLength;
     }
@@ -316,7 +316,7 @@ public class File
             throw new NullPointerException();
         }
         if (parent != null) {
-            if (parent.equals("")) {
+            if (parent.isEmpty()) {
                 this.path = fs.resolve(fs.getDefaultParent(),
                                        fs.normalize(child));
             } else {
@@ -359,7 +359,7 @@ public class File
             throw new NullPointerException();
         }
         if (parent != null) {
-            if (parent.path.equals("")) {
+            if (parent.path.isEmpty()) {
                 this.path = fs.resolve(fs.getDefaultParent(),
                                        fs.normalize(child));
             } else {
@@ -426,7 +426,7 @@ public class File
         if (uri.getRawQuery() != null)
             throw new IllegalArgumentException("URI has a query component");
         String p = uri.getPath();
-        if (p.equals(""))
+        if (p.isEmpty())
             throw new IllegalArgumentException("URI path component is empty");
 
         // Okay, now initialize

src/java.base/share/classes/java/lang/SecurityManager.java

@@ -1201,7 +1201,7 @@ public class SecurityManager {
 
     private static String[] getPackages(String p) {
         String packages[] = null;
-        if (p != null && !p.equals("")) {
+        if (p != null && !p.isEmpty()) {
             java.util.StringTokenizer tok =
                 new java.util.StringTokenizer(p, ",");
             int n = tok.countTokens();

src/java.base/share/classes/java/lang/System.java

@@ -970,7 +970,7 @@ public final class System {
         if (key == null) {
             throw new NullPointerException("key can't be null");
         }
-        if (key.equals("")) {
+        if (key.isEmpty()) {
             throw new IllegalArgumentException("key can't be empty");
         }
     }

src/java.base/share/classes/java/lang/reflect/Parameter.java

@@ -174,9 +174,9 @@ public final class Parameter implements AnnotatedElement {
      */
     public String getName() {
         // Note: empty strings as parameter names are now outlawed.
-        // The .equals("") is for compatibility with current JVM
+        // The .isEmpty() is for compatibility with current JVM
         // behavior.  It may be removed at some point.
-        if(name == null || name.equals(""))
+        if(name == null || name.isEmpty())
             return "arg" + index;
         else
             return name;

src/java.base/share/classes/java/net/HostPortrange.java

@@ -241,7 +241,7 @@ class HostPortrange {
     int[] parsePort(String port)
     {
 
-        if (port == null || port.equals("")) {
+        if (port == null || port.isEmpty()) {
             return defaultPort();
         }
 
@@ -260,13 +260,13 @@ class HostPortrange {
                 String high = port.substring(dash+1);
                 int l,h;
 
-                if (low.equals("")) {
+                if (low.isEmpty()) {
                     l = PORT_MIN;
                 } else {
                     l = Integer.parseInt(low);
                 }
 
-                if (high.equals("")) {
+                if (high.isEmpty()) {
                     h = PORT_MAX;
                 } else {
                     h = Integer.parseInt(high);

src/java.base/share/classes/java/net/InetAddress.java

@@ -1009,7 +1009,7 @@ class InetAddress implements java.io.Serializable {
                         + " not found ");
             }
 
-            if ((host == null) || (host.equals("")) || (host.equals(" "))) {
+            if ((host == null) || (host.isEmpty()) || (host.equals(" "))) {
                 throw new UnknownHostException("Requested address "
                         + addrString
                         + " resolves to an invalid entry in hosts file "
@@ -1046,7 +1046,7 @@ class InetAddress implements java.io.Serializable {
                         hostEntry = removeComments(hostEntry);
                         if (hostEntry.contains(host)) {
                             addrStr = extractHostAddr(hostEntry, host);
-                            if ((addrStr != null) && (!addrStr.equals(""))) {
+                            if ((addrStr != null) && (!addrStr.isEmpty())) {
                                 addr = createAddressByteArray(addrStr);
                                 if (inetAddresses == null) {
                                     inetAddresses = new ArrayList<>(1);

src/java.base/share/classes/java/net/SocketPermission.java

@@ -305,7 +305,7 @@ public final class SocketPermission extends Permission
     }
 
     private static String getHost(String host) {
-        if (host.equals("")) {
+        if (host.isEmpty()) {
             return "localhost";
         } else {
             /* IPv6 literal address used in this context should follow
@@ -344,7 +344,7 @@ public final class SocketPermission extends Permission
         throws Exception
     {
 
-        if (port == null || port.equals("") || port.equals("*")) {
+        if (port == null || port.isEmpty() || port.equals("*")) {
             return new int[] {PORT_MIN, PORT_MAX};
         }
 
@@ -358,13 +358,13 @@ public final class SocketPermission extends Permission
             String high = port.substring(dash+1);
             int l,h;
 
-            if (low.equals("")) {
+            if (low.isEmpty()) {
                 l = PORT_MIN;
             } else {
                 l = Integer.parseInt(low);
             }
 
-            if (high.equals("")) {
+            if (high.isEmpty()) {
                 h = PORT_MAX;
             } else {
                 h = Integer.parseInt(high);
@@ -496,7 +496,7 @@ public final class SocketPermission extends Permission
             throw new NullPointerException("action can't be null");
         }
 
-        if (action.equals("")) {
+        if (action.isEmpty()) {
             throw new IllegalArgumentException("action can't be empty");
         }
 

src/java.base/share/classes/java/net/URLPermission.java

@@ -533,11 +533,11 @@ public final class URLPermission extends Permission {
             String thishost = this.p.hostname();
             String thathost = that.p.hostname();
 
-            if (p.wildcard() && thishost.equals("")) {
+            if (p.wildcard() && thishost.isEmpty()) {
                 // this "*" implies all others
                 return true;
             }
-            if (that.p.wildcard() && thathost.equals("")) {
+            if (that.p.wildcard() && thathost.isEmpty()) {
                 // that "*" can only be implied by this "*"
                 return false;
             }

src/java.base/share/classes/java/net/URLStreamHandler.java

@@ -437,7 +437,7 @@ public abstract class URLStreamHandler {
             return u.hostAddress;
 
         String host = u.getHost();
-        if (host == null || host.equals("")) {
+        if (host == null || host.isEmpty()) {
             return null;
         } else {
             try {

src/java.base/share/classes/java/util/Locale.java

@@ -2226,10 +2226,10 @@ public final class Locale implements Cloneable, Serializable {
             default:
                 return Arrays.stream(stringList).reduce("",
                     (s1, s2) -> {
-                        if (s1.equals("")) {
+                        if (s1.isEmpty()) {
                             return s2;
                         }
-                        if (s2.equals("")) {
+                        if (s2.isEmpty()) {
                             return s1;
                         }
                         return MessageFormat.format(pattern, s1, s2);
@@ -3069,7 +3069,7 @@ public final class Locale implements Cloneable, Serializable {
 
         private static boolean isSubtagIllFormed(String subtag,
                                                  boolean isFirstSubtag) {
-            if (subtag.equals("") || subtag.length() > 8) {
+            if (subtag.isEmpty() || subtag.length() > 8) {
                 return true;
             } else if (subtag.equals("*")) {
                 return false;

src/java.base/share/classes/java/util/jar/Pack200.java

@@ -704,7 +704,7 @@ public abstract class Pack200 {
             if (impl == null) {
                 // The first time, we must decide which class to use.
                 implName = GetPropertyAction.privilegedGetProperty(prop,"");
-                if (implName != null && !implName.equals(""))
+                if (implName != null && !implName.isEmpty())
                     impl = Class.forName(implName);
                 else if (PACK_PROVIDER.equals(prop))
                     impl = com.sun.java.util.jar.pack.PackerImpl.class;

src/java.base/share/classes/java/util/regex/Pattern.java

@@ -1290,7 +1290,7 @@ public final class Pattern
         // Construct result
         int resultSize = matchList.size();
         if (limit == 0)
-            while (resultSize > 0 && matchList.get(resultSize-1).equals(""))
+            while (resultSize > 0 && matchList.get(resultSize-1).isEmpty())
                 resultSize--;
         String[] result = new String[resultSize];
         return matchList.subList(0, resultSize).toArray(result);

src/java.base/share/classes/javax/crypto/Cipher.java

@@ -531,7 +531,7 @@ public class Cipher {
     public static final Cipher getInstance(String transformation)
             throws NoSuchAlgorithmException, NoSuchPaddingException
     {
-        if ((transformation == null) || transformation.equals("")) {
+        if ((transformation == null) || transformation.isEmpty()) {
             throw new NoSuchAlgorithmException("Null or empty transformation");
         }
         List<Transform> transforms = getTransforms(transformation);
@@ -631,7 +631,7 @@ public class Cipher {
             throws NoSuchAlgorithmException, NoSuchProviderException,
             NoSuchPaddingException
     {
-        if ((transformation == null) || transformation.equals("")) {
+        if ((transformation == null) || transformation.isEmpty()) {
             throw new NoSuchAlgorithmException("Null or empty transformation");
         }
         if ((provider == null) || (provider.length() == 0)) {
@@ -698,7 +698,7 @@ public class Cipher {
                                            Provider provider)
             throws NoSuchAlgorithmException, NoSuchPaddingException
     {
-        if ((transformation == null) || transformation.equals("")) {
+        if ((transformation == null) || transformation.isEmpty()) {
             throw new NoSuchAlgorithmException("Null or empty transformation");
         }
         if (provider == null) {
@@ -2840,4 +2840,4 @@ public class Cipher {
         sb.append(", algorithm from: ").append(getProviderName());
         return sb.toString();
     }
-}
+}

src/java.base/share/classes/javax/net/ssl/SSLParameters.java

@@ -668,7 +668,7 @@ public class SSLParameters {
         String[] tempProtocols = protocols.clone();
 
         for (String p : tempProtocols) {
-            if (p == null || p.equals("")) {
+            if (p == null || p.isEmpty()) {
                 throw new IllegalArgumentException(
                     "An element of protocols was null/empty");
             }

src/java.base/share/classes/jdk/internal/loader/URLClassPath.java

@@ -97,10 +97,10 @@ public class URLClassPath {
         JAVA_VERSION = props.getProperty("java.version");
         DEBUG = (props.getProperty("sun.misc.URLClassPath.debug") != null);
         String p = props.getProperty("sun.misc.URLClassPath.disableJarChecking");
-        DISABLE_JAR_CHECKING = p != null ? p.equals("true") || p.equals("") : false;
+        DISABLE_JAR_CHECKING = p != null ? p.equals("true") || p.isEmpty() : false;
 
         p = props.getProperty("jdk.net.URLClassPath.disableRestrictedPermissions");
-        DISABLE_ACC_CHECKING = p != null ? p.equals("true") || p.equals("") : false;
+        DISABLE_ACC_CHECKING = p != null ? p.equals("true") || p.isEmpty() : false;
 
         // This property will be removed in a later release
         p = props.getProperty("jdk.net.URLClassPath.disableClassPathURLCheck", "true");

src/java.base/share/classes/sun/net/www/protocol/jar/URLJarFile.java

@@ -111,7 +111,7 @@ public class URLJarFile extends JarFile {
              * 'file:' URLs can be accessible through ftp.
              */
             String host = url.getHost();
-            if (host == null || host.equals("") || host.equals("~") ||
+            if (host == null || host.isEmpty() || host.equals("~") ||
                 host.equalsIgnoreCase("localhost"))
                 return true;
         }

src/java.base/share/classes/sun/net/www/protocol/mailto/Handler.java

@@ -127,7 +127,7 @@ public class Handler extends URLStreamHandler {
          * Let's just make sure we DO have an Email address in the URL.
          */
         boolean nogood = false;
-        if (file == null || file.equals(""))
+        if (file == null || file.isEmpty())
             nogood = true;
         else {
             boolean allwhites = true;

src/java.base/share/classes/sun/security/provider/PolicyFile.java

@@ -1608,7 +1608,7 @@ public class PolicyFile extends java.security.Policy {
             if (u.getProtocol().equals("file")) {
                 boolean isLocalFile = false;
                 String host = u.getHost();
-                isLocalFile = (host == null || host.equals("") ||
+                isLocalFile = (host == null || host.isEmpty() ||
                     host.equals("~") || host.equalsIgnoreCase("localhost"));
 
                 if (isLocalFile) {

src/java.base/share/classes/sun/security/util/ConsoleCallbackHandler.java

@@ -103,7 +103,7 @@ public class ConsoleCallbackHandler implements CallbackHandler {
                 System.err.flush();
 
                 String result = readLine();
-                if (result.equals("")) {
+                if (result.isEmpty()) {
                     result = nc.getDefaultName();
                 }
 
@@ -212,7 +212,7 @@ public class ConsoleCallbackHandler implements CallbackHandler {
             prompt = "";
         }
         prompt = prefix + prompt;
-        if (!prompt.equals("")) {
+        if (!prompt.isEmpty()) {
             System.err.println(prompt);
         }
 

src/java.base/share/classes/sun/security/util/DomainName.java

@@ -363,7 +363,7 @@ class DomainName {
             }
 
             private static int numLabels(String rule) {
-                if (rule.equals("")) {
+                if (rule.isEmpty()) {
                     return 0;
                 }
                 int len = rule.length();

src/java.base/unix/classes/java/io/UnixFileSystem.java

@@ -103,7 +103,7 @@ class UnixFileSystem extends FileSystem {
     }
 
     public String resolve(String parent, String child) {
-        if (child.equals("")) return parent;
+        if (child.isEmpty()) return parent;
         if (child.charAt(0) == '/') {
             if (parent.equals("/")) return child;
             return parent + child;

src/java.base/unix/classes/sun/net/www/protocol/file/Handler.java

@@ -75,7 +75,7 @@ public class Handler extends URLStreamHandler {
     public synchronized URLConnection openConnection(URL u, Proxy p)
            throws IOException {
         String host = u.getHost();
-        if (host == null || host.equals("") || host.equals("~") ||
+        if (host == null || host.isEmpty() || host.equals("~") ||
             host.equalsIgnoreCase("localhost")) {
             File file = new File(ParseUtil.decode(u.getPath()));
             return createFileURLConnection(u, file);

src/java.base/windows/classes/jdk/internal/loader/FileURLMapper.java

@@ -55,7 +55,7 @@ public class FileURLMapper {
             return file;
         }
         String host = url.getHost();
-        if (host != null && !host.equals("") &&
+        if (host != null && !host.isEmpty() &&
             !"localhost".equalsIgnoreCase(host)) {
             String rest = url.getFile();
             String s = host + ParseUtil.decode (url.getFile());

src/java.base/windows/classes/sun/net/www/protocol/file/Handler.java

@@ -83,7 +83,7 @@ public class Handler extends URLStreamHandler {
         path = path.replace('/', '\\');
         path = path.replace('|', ':');
 
-        if ((host == null) || host.equals("") ||
+        if ((host == null) || host.isEmpty() ||
                 host.equalsIgnoreCase("localhost") ||
                 host.equals("~")) {
            return createFileURLConnection(url, new File(path));

src/java.base/windows/classes/sun/net/www/protocol/jar/JarFileFactory.java

@@ -76,7 +76,7 @@ class JarFileFactory implements URLJarFile.URLJarFileCloseController {
             // Deal with UNC pathnames specially. See 4180841
 
             String host = url.getHost();
-            if (host != null && !host.equals("") &&
+            if (host != null && !host.isEmpty() &&
                 !host.equalsIgnoreCase("localhost")) {
 
                 url = new URL("file", "", "//" + host + url.getPath());

src/java.base/windows/classes/sun/nio/fs/WindowsUriSupport.java

@@ -128,12 +128,12 @@ class WindowsUriSupport {
         if (uri.getRawQuery() != null)
             throw new IllegalArgumentException("URI has a query component");
         String path = uri.getPath();
-        if (path.equals(""))
+        if (path.isEmpty())
             throw new IllegalArgumentException("URI path component is empty");
 
         // UNC
         String auth = uri.getRawAuthority();
-        if (auth != null && !auth.equals("")) {
+        if (auth != null && !auth.isEmpty()) {
             String host = uri.getHost();
             if (host == null)
                 throw new IllegalArgumentException("URI authority component has undefined host");

src/java.logging/share/classes/java/util/logging/LogManager.java

@@ -890,7 +890,7 @@ public class LogManager {
         // Gets a node in our tree of logger nodes.
         // If necessary, create it.
         LogNode getNode(String name) {
-            if (name == null || name.equals("")) {
+            if (name == null || name.isEmpty()) {
                 return root;
             }
             LogNode node = root;
@@ -1486,7 +1486,7 @@ public class LogManager {
 
         // Reset Logger level
         String name = logger.getName();
-        if (name != null && name.equals("")) {
+        if (name != null && name.isEmpty()) {
             // This is the root logger.
             logger.setLevel(defaultLevel);
         } else {

src/java.management.rmi/share/classes/javax/management/remote/rmi/RMIConnectorServer.java

@@ -289,7 +289,7 @@ public class RMIConnectorServer extends JMXConnectorServer {
                 throw new MalformedURLException(msg);
             }
             final String urlPath = url.getURLPath();
-            if (!urlPath.equals("")
+            if (!urlPath.isEmpty()
                 && !urlPath.equals("/")
                 && !urlPath.startsWith("/jndi/")) {
                 final String msg = "URL path must be empty or start with " +
@@ -746,7 +746,7 @@ public class RMIConnectorServer extends JMXConnectorServer {
             port = 0;
         } else {
             protocol = address.getProtocol();
-            host = (address.getHost().equals("")) ? null : address.getHost();
+            host = (address.getHost().isEmpty()) ? null : address.getHost();
             port = address.getPort();
         }
 

src/java.management/share/classes/com/sun/jmx/remote/internal/ServerNotifForwarder.java

@@ -114,7 +114,7 @@ public class ServerNotifForwarder {
 
         // 6238731: set the default domain if no domain is set.
         ObjectName nn = name;
-        if (name.getDomain() == null || name.getDomain().equals("")) {
+        if (name.getDomain() == null || name.getDomain().isEmpty()) {
             try {
                 nn = ObjectName.getInstance(mbeanServer.getDefaultDomain(),
                                             name.getKeyPropertyList());

src/java.management/share/classes/javax/management/ImmutableDescriptor.java

@@ -110,7 +110,7 @@ public class ImmutableDescriptor implements Descriptor {
                 new TreeMap<String, Object>(String.CASE_INSENSITIVE_ORDER);
         for (Map.Entry<String, ?> entry : fields.entrySet()) {
             String name = entry.getKey();
-            if (name == null || name.equals(""))
+            if (name == null || name.isEmpty())
                 throw new IllegalArgumentException("Empty or null field name");
             if (map.containsKey(name))
                 throw new IllegalArgumentException("Duplicate name: " + name);
@@ -166,7 +166,7 @@ public class ImmutableDescriptor implements Descriptor {
                 new TreeMap<String, Object>(String.CASE_INSENSITIVE_ORDER);
         for (int i = 0; i < fieldNames.length; i++) {
             String name = fieldNames[i];
-            if (name == null || name.equals(""))
+            if (name == null || name.isEmpty())
                 throw new IllegalArgumentException("Empty or null field name");
             Object old = map.put(name, fieldValues[i]);
             if (old != null) {
@@ -333,7 +333,7 @@ public class ImmutableDescriptor implements Descriptor {
         Object[] result = new Object[fieldNames.length];
         for (int i = 0; i < fieldNames.length; i++) {
             String name = fieldNames[i];
-            if (name != null && !name.equals(""))
+            if (name != null && !name.isEmpty())
                 result[i] = getFieldValue(name);
         }
         return result;
@@ -543,7 +543,7 @@ public class ImmutableDescriptor implements Descriptor {
     }
 
     private static void checkIllegalFieldName(String name) {
-        if (name == null || name.equals(""))
+        if (name == null || name.isEmpty())
             illegal("Null or empty field name");
     }
 

src/java.management/share/classes/javax/management/MBeanPermission.java

@@ -256,7 +256,7 @@ public class MBeanPermission extends Permission {
         if (actions == null)
             throw new IllegalArgumentException("MBeanPermission: " +
                                                "actions can't be null");
-        if (actions.equals(""))
+        if (actions.isEmpty())
             throw new IllegalArgumentException("MBeanPermission: " +
                                                "actions can't be empty");
 
@@ -279,7 +279,7 @@ public class MBeanPermission extends Permission {
             throw new IllegalArgumentException("MBeanPermission name " +
                                                "cannot be null");
 
-        if (name.equals(""))
+        if (name.isEmpty())
             throw new IllegalArgumentException("MBeanPermission name " +
                                                "cannot be empty");
 
@@ -310,7 +310,7 @@ public class MBeanPermission extends Permission {
                     //
                     String on = name.substring(openingBracket + 1,
                                                name.length() - 1);
-                    if (on.equals(""))
+                    if (on.isEmpty())
                         objectName = ObjectName.WILDCARD;
                     else if (on.equals("-"))
                         objectName = null;
@@ -359,7 +359,7 @@ public class MBeanPermission extends Permission {
         if (className == null || className.equals("-")) {
             classNamePrefix = null;
             classNameExactMatch = false;
-        } else if (className.equals("") || className.equals("*")) {
+        } else if (className.isEmpty() || className.equals("*")) {
             classNamePrefix = "";
             classNameExactMatch = false;
         } else if (className.endsWith(".*")) {
@@ -375,7 +375,7 @@ public class MBeanPermission extends Permission {
     private void setMember(String member) {
         if (member == null || member.equals("-"))
             this.member = null;
-        else if (member.equals(""))
+        else if (member.isEmpty())
             this.member = "*";
         else
             this.member = member;

src/java.management/share/classes/javax/management/modelmbean/DescriptorSupport.java

@@ -443,7 +443,7 @@ public class DescriptorSupport
         init(null);
 
         for (int i=0; i < fields.length; i++) {
-            if ((fields[i] == null) || (fields[i].equals(""))) {
+            if ((fields[i] == null) || (fields[i].isEmpty())) {
                 continue;
             }
             int eq_separator = fields[i].indexOf('=');
@@ -467,7 +467,7 @@ public class DescriptorSupport
                 fieldValue = fields[i].substring(eq_separator+1);
             }
 
-            if (fieldName.equals("")) {
+            if (fieldName.isEmpty()) {
                 if (MODELMBEAN_LOGGER.isLoggable(Level.TRACE)) {
                     MODELMBEAN_LOGGER.log(Level.TRACE,
                             "Descriptor(String... fields) " +
@@ -500,7 +500,7 @@ public class DescriptorSupport
     public synchronized Object getFieldValue(String fieldName)
             throws RuntimeOperationsException {
 
-        if ((fieldName == null) || (fieldName.equals(""))) {
+        if ((fieldName == null) || (fieldName.isEmpty())) {
             if (MODELMBEAN_LOGGER.isLoggable(Level.TRACE)) {
                 MODELMBEAN_LOGGER.log(Level.TRACE,
                         "Illegal arguments: null field name");
@@ -522,7 +522,7 @@ public class DescriptorSupport
             throws RuntimeOperationsException {
 
         // field name cannot be null or empty
-        if ((fieldName == null) || (fieldName.equals(""))) {
+        if ((fieldName == null) || (fieldName.isEmpty())) {
             if (MODELMBEAN_LOGGER.isLoggable(Level.TRACE)) {
                 MODELMBEAN_LOGGER.log(Level.TRACE,
                         "Illegal arguments: null or empty field name");
@@ -664,7 +664,7 @@ public class DescriptorSupport
                 responseFields[i++] = value;
         } else {
             for (i=0; i < fieldNames.length; i++) {
-                if ((fieldNames[i] == null) || (fieldNames[i].equals(""))) {
+                if ((fieldNames[i] == null) || (fieldNames[i].isEmpty())) {
                     responseFields[i] = null;
                 } else {
                     responseFields[i] = getFieldValue(fieldNames[i]);
@@ -700,7 +700,7 @@ public class DescriptorSupport
         }
 
         for (int i=0; i < fieldNames.length; i++) {
-            if (( fieldNames[i] == null) || (fieldNames[i].equals(""))) {
+            if (( fieldNames[i] == null) || (fieldNames[i].isEmpty())) {
                 if (MODELMBEAN_LOGGER.isLoggable(Level.TRACE)) {
                     MODELMBEAN_LOGGER.log(Level.TRACE,
                             "Null field name encountered at element " + i);
@@ -733,7 +733,7 @@ public class DescriptorSupport
     }
 
     public synchronized void removeField(String fieldName) {
-        if ((fieldName == null) || (fieldName.equals(""))) {
+        if ((fieldName == null) || (fieldName.isEmpty())) {
             return;
         }
 
@@ -862,7 +862,7 @@ public class DescriptorSupport
         String thisDescType = (String)(getFieldValue("descriptorType"));
 
         if ((thisName == null) || (thisDescType == null) ||
-            (thisName.equals("")) || (thisDescType.equals(""))) {
+            (thisName.isEmpty()) || (thisDescType.isEmpty())) {
             return false;
         }
 
@@ -912,7 +912,7 @@ public class DescriptorSupport
 
 
     private boolean validateField(String fldName, Object fldValue) {
-        if ((fldName == null) || (fldName.equals("")))
+        if ((fldName == null) || (fldName.isEmpty()))
             return false;
         String SfldValue = "";
         boolean isAString = false;
@@ -931,7 +931,7 @@ public class DescriptorSupport
             fldName.equalsIgnoreCase("Class")) {
             if (fldValue == null || !isAString)
                 return false;
-            if (nameOrDescriptorType && SfldValue.equals(""))
+            if (nameOrDescriptorType && SfldValue.isEmpty())
                 return false;
             return true;
         } else if (fldName.equalsIgnoreCase("visibility")) {

src/java.management/share/classes/javax/management/modelmbean/ModelMBeanInfoSupport.java

@@ -367,7 +367,7 @@ public class ModelMBeanInfoSupport extends MBeanInfo implements ModelMBeanInfo {
             MODELMBEAN_LOGGER.log(Level.TRACE, "Entry");
         }
 
-        if ((inDescriptorType == null) || (inDescriptorType.equals(""))) {
+        if ((inDescriptorType == null) || (inDescriptorType.isEmpty())) {
             inDescriptorType = "all";
         }
 
@@ -600,7 +600,7 @@ public class ModelMBeanInfoSupport extends MBeanInfo implements ModelMBeanInfo {
             inDescriptor = new DescriptorSupport();
         }
 
-        if ((inDescriptorType == null) || (inDescriptorType.equals(""))) {
+        if ((inDescriptorType == null) || (inDescriptorType.isEmpty())) {
             inDescriptorType =
                     (String) inDescriptor.getFieldValue("descriptorType");
 

src/java.management/share/classes/javax/management/openmbean/CompositeType.java

@@ -171,7 +171,7 @@ public class CompositeType extends OpenType<CompositeData> {
 
     private static void checkForEmptyString(String[] arg, String argName) {
         for (int i=0; i<arg.length; i++) {
-            if (arg[i].trim().equals("")) {
+            if (arg[i].trim().isEmpty()) {
                 throw new IllegalArgumentException("Argument's element "+ argName +"["+ i +"] cannot be an empty string.");
             }
         }

src/java.management/share/classes/javax/management/openmbean/OpenMBeanAttributeInfoSupport.java

@@ -456,11 +456,11 @@ public class OpenMBeanAttributeInfoSupport
             throw new IllegalArgumentException("OpenType cannot be null");
 
         if (info.getName() == null ||
-                info.getName().trim().equals(""))
+                info.getName().trim().isEmpty())
             throw new IllegalArgumentException("Name cannot be null or empty");
 
         if (info.getDescription() == null ||
-                info.getDescription().trim().equals(""))
+                info.getDescription().trim().isEmpty())
             throw new IllegalArgumentException("Description cannot be null or empty");
 
         // Check and initialize defaultValue

src/java.management/share/classes/javax/management/openmbean/OpenMBeanConstructorInfoSupport.java

@@ -124,11 +124,11 @@ public class OpenMBeanConstructorInfoSupport
         // check parameters that should not be null or empty
         // (unfortunately it is not done in superclass :-( ! )
         //
-        if (name == null || name.trim().equals("")) {
+        if (name == null || name.trim().isEmpty()) {
             throw new IllegalArgumentException("Argument name cannot be " +
                                                "null or empty");
         }
-        if (description == null || description.trim().equals("")) {
+        if (description == null || description.trim().isEmpty()) {
             throw new IllegalArgumentException("Argument description cannot " +
                                                "be null or empty");
         }

src/java.management/share/classes/javax/management/openmbean/OpenMBeanOperationInfoSupport.java

@@ -163,11 +163,11 @@ public class OpenMBeanOperationInfoSupport
         // check parameters that should not be null or empty
         // (unfortunately it is not done in superclass :-( ! )
         //
-        if (name == null || name.trim().equals("")) {
+        if (name == null || name.trim().isEmpty()) {
             throw new IllegalArgumentException("Argument name cannot " +
                                                "be null or empty");
         }
-        if (description == null || description.trim().equals("")) {
+        if (description == null || description.trim().isEmpty()) {
             throw new IllegalArgumentException("Argument description cannot " +
                                                "be null or empty");
         }

src/java.management/share/classes/javax/management/openmbean/OpenType.java

@@ -268,7 +268,7 @@ public abstract class OpenType<T> implements Serializable {
     /* Return argValue.trim() provided argValue is neither null nor empty;
        otherwise throw IllegalArgumentException.  */
     private static String valid(String argName, String argValue) {
-        if (argValue == null || (argValue = argValue.trim()).equals(""))
+        if (argValue == null || (argValue = argValue.trim()).isEmpty())
             throw new IllegalArgumentException("Argument " + argName +
                                                " cannot be null or empty");
         return argValue;

src/java.management/share/classes/javax/management/openmbean/TabularType.java

@@ -165,7 +165,7 @@ public class TabularType extends OpenType<TabularData> {
      */
     private static void checkForEmptyString(String[] arg, String argName) {
         for (int i=0; i<arg.length; i++) {
-            if (arg[i].trim().equals("")) {
+            if (arg[i].trim().isEmpty()) {
                 throw new IllegalArgumentException("Argument's element "+ argName +"["+ i +"] cannot be an empty string.");
             }
         }

src/java.management/share/classes/javax/management/remote/JMXConnectorFactory.java

@@ -405,7 +405,7 @@ public class JMXConnectorFactory {
         }
 
         final String pkgs = (String) pkgsObject;
-        if (pkgs.trim().equals(""))
+        if (pkgs.trim().isEmpty())
             return null;
 
         // pkgs may not contain an empty element

src/java.management/share/classes/sun/management/MappedMXBeanType.java

@@ -663,7 +663,7 @@ public abstract class MappedMXBeanType {
                         continue;
                     }
 
-                    if (rest.equals("") ||
+                    if (rest.isEmpty() ||
                         method.getParameterTypes().length > 0 ||
                         type == void.class ||
                         rest.equals("Class")) {

src/java.naming/share/classes/com/sun/jndi/ldap/Filter.java

@@ -53,7 +53,7 @@ final class Filter {
     static void encodeFilterString(BerEncoder ber, String filterStr,
         boolean isLdapv3) throws IOException, NamingException {
 
-        if ((filterStr == null) || (filterStr.equals(""))) {
+        if ((filterStr == null) || (filterStr.isEmpty())) {
             throw new InvalidSearchFilterException("Empty filter");
         }
         byte[] filter;

src/java.naming/share/classes/com/sun/jndi/ldap/LdapCtx.java

@@ -915,7 +915,7 @@ final public class LdapCtx extends ComponentDirContext
         boolean directUpdate) throws NamingException {
 
             // Handle the empty name
-            if (dn.equals("")) {
+            if (dn.isEmpty()) {
                 return attrs;
             }
 
@@ -1271,7 +1271,7 @@ final public class LdapCtx extends ComponentDirContext
         int prefixLast = prefix.size() - 1;
 
         if (name.isEmpty() || prefix.isEmpty() ||
-                name.get(0).equals("") || prefix.get(prefixLast).equals("")) {
+                name.get(0).isEmpty() || prefix.get(prefixLast).isEmpty()) {
             return super.composeName(name, prefix);
         }
 
@@ -1300,9 +1300,9 @@ final public class LdapCtx extends ComponentDirContext
 
     // used by LdapSearchEnumeration
     private static String concatNames(String lesser, String greater) {
-        if (lesser == null || lesser.equals("")) {
+        if (lesser == null || lesser.isEmpty()) {
             return greater;
-        } else if (greater == null || greater.equals("")) {
+        } else if (greater == null || greater.isEmpty()) {
             return lesser;
         } else {
             return (lesser + "," + greater);
@@ -3036,7 +3036,7 @@ final public class LdapCtx extends ComponentDirContext
             }
 
             // extract SLAPD-style referrals from errorMessage
-            if ((res.errorMessage != null) && (!res.errorMessage.equals(""))) {
+            if ((res.errorMessage != null) && (!res.errorMessage.isEmpty())) {
                 res.referrals = extractURLs(res.errorMessage);
             } else {
                 e = new PartialResultException(msg);

src/java.naming/share/classes/com/sun/jndi/ldap/LdapReferralContext.java

@@ -182,7 +182,7 @@ final class LdapReferralContext implements DirContext, LdapContext {
         if (urlString == null) {
             urlName = null;
         } else {
-            urlName = urlString.equals("") ? new CompositeName() :
+            urlName = urlString.isEmpty() ? new CompositeName() :
                 new CompositeName().add(urlString);
         }
     }
@@ -888,7 +888,7 @@ final class LdapReferralContext implements DirContext, LdapContext {
 
     // ---------------------- Private methods  ---------------------
     private Name toName(String name) throws InvalidNameException {
-        return name.equals("") ? new CompositeName() :
+        return name.isEmpty() ? new CompositeName() :
             new CompositeName().add(name);
     }
 

src/java.naming/share/classes/com/sun/jndi/ldap/LdapSearchEnumeration.java

@@ -97,13 +97,13 @@ final class LdapSearchEnumeration
 
         // Name relative to search context
         CompositeName cn = new CompositeName();
-        if (!relStart.equals("")) {
+        if (!relStart.isEmpty()) {
             cn.add(relStart);
         }
 
         // Name relative to homeCtx
         CompositeName rcn = new CompositeName();
-        if (!relHome.equals("")) {
+        if (!relHome.isEmpty()) {
             rcn.add(relHome);
         }
         //System.err.println("relStart: " + cn);

src/java.naming/share/classes/com/sun/jndi/ldap/LdapURL.java

@@ -197,7 +197,7 @@ final public class LdapURL extends Uri {
 
         // path begins with a '/' or is empty
 
-        if (path.equals("")) {
+        if (path.isEmpty()) {
             return;
         }
 

src/java.naming/share/classes/com/sun/jndi/ldap/NamingEventNotifier.java

@@ -115,7 +115,7 @@ final class NamingEventNotifier implements Runnable {
         try {
             Continuation cont = new Continuation();
             cont.setError(this, info.name);
-            Name nm = (info.name == null || info.name.equals("")) ?
+            Name nm = (info.name == null || info.name.isEmpty()) ?
                 new CompositeName() : new CompositeName().add(info.name);
 
             results = context.searchAux(nm, info.filter, info.controls,

src/java.naming/share/classes/com/sun/jndi/toolkit/ctx/AtomicContext.java

@@ -243,7 +243,7 @@ public abstract class AtomicContext extends ComponentContext {
 
 
     protected boolean isEmpty(String name) {
-        return name == null || name.equals("");
+        return name == null || name.isEmpty();
     }
 
 // ------ implementations of c_  and c_*_nns methods using
@@ -510,7 +510,7 @@ public abstract class AtomicContext extends ComponentContext {
       */
     protected void a_processJunction_nns(String name, Continuation cont)
         throws NamingException {
-            if (name.equals("")) {
+            if (name.isEmpty()) {
                 NameNotFoundException e = new NameNotFoundException();
                 cont.setErrorNNS(this, name);
                 throw cont.fillInException(e);

src/java.naming/share/classes/com/sun/jndi/toolkit/ctx/ComponentContext.java

@@ -105,7 +105,7 @@ public abstract class ComponentContext extends PartialCompositeContext {
         throws NamingException {
         int separator;
         // if no name to parse, or if we're already at boundary
-        if (name.isEmpty() ||  name.get(0).equals("")) {
+        if (name.isEmpty() ||  name.get(0).isEmpty()) {
             separator = 0;
         } else {
             separator = 1;
@@ -379,7 +379,7 @@ public abstract class ComponentContext extends PartialCompositeContext {
         if (tail == null || tail.isEmpty()) {
 //System.out.println("terminal : " + head);
             ret = TERMINAL_COMPONENT;
-        } else if (!tail.get(0).equals("")) {
+        } else if (!tail.get(0).isEmpty()) {
             // tail does not begin with "/"
 /*
             if (head.isEmpty()) {
@@ -468,7 +468,7 @@ public abstract class ComponentContext extends PartialCompositeContext {
     void checkAndAdjustRemainingName(Name rname) throws InvalidNameException {
         int count;
         if (rname != null && (count=rname.size()) > 1 &&
-            rname.get(count-1).equals("")) {
+            rname.get(count-1).isEmpty()) {
             rname.remove(count-1);
         }
     }
@@ -477,7 +477,7 @@ public abstract class ComponentContext extends PartialCompositeContext {
     protected boolean isAllEmpty(Name n) {
         int count = n.size();
         for (int i =0; i < count; i++ ) {
-            if (!n.get(i).equals("")) {
+            if (!n.get(i).isEmpty()) {
                 return false;
             }
         }

src/java.naming/share/classes/com/sun/jndi/toolkit/ctx/Continuation.java

@@ -203,7 +203,7 @@ public class Continuation extends ResolveResult {
     public void setErrorNNS(Object resObj, String remain) {
         CompositeName rname = new CompositeName();
         try {
-            if (remain != null && !remain.equals(""))
+            if (remain != null && !remain.isEmpty())
                 rname.add(remain);
 
             rname.add("");
@@ -247,7 +247,7 @@ public class Continuation extends ResolveResult {
      */
     public void setError(Object resObj, String remain) {
         CompositeName rname = new CompositeName();
-        if (remain != null && !remain.equals("")) {
+        if (remain != null && !remain.isEmpty()) {
             try {
                 rname.add(remain);
             } catch (InvalidNameException e) {
@@ -375,14 +375,14 @@ public class Continuation extends ResolveResult {
     public void setContinue(Object obj, String relResName,
         Context currCtx, String remain) {
         CompositeName relname = new CompositeName();
-        if (!relResName.equals("")) {
+        if (!relResName.isEmpty()) {
             try {
                 relname.add(relResName);
             } catch (NamingException e){}
         }
 
         CompositeName rname = new CompositeName();
-        if (!remain.equals("")) {
+        if (!remain.isEmpty()) {
             try {
                 rname.add(remain);
             } catch (NamingException e) {

src/java.naming/share/classes/com/sun/jndi/toolkit/ctx/PartialCompositeContext.java

@@ -477,9 +477,9 @@ public abstract class PartialCompositeContext implements Context, Resolver {
         int len = prefix.size();
 
         if (!allEmpty(prefix) && !allEmpty(name)) {
-            if (res.get(len - 1).equals("")) {
+            if (res.get(len - 1).isEmpty()) {
                 res.remove(len - 1);
-            } else if (res.get(len).equals("")) {
+            } else if (res.get(len).isEmpty()) {
                 res.remove(len);
             }
         }

src/java.naming/share/classes/com/sun/jndi/toolkit/dir/ContextEnumerator.java

@@ -138,7 +138,7 @@ public class ContextEnumerator implements NamingEnumeration<Binding> {
         // if the name is relative, we need to add it to the name of this
         // context to keep it relative w.r.t. the root context we are
         // enumerating
-        if(oldBinding.isRelative() && !contextName.equals("")) {
+        if(oldBinding.isRelative() && !contextName.isEmpty()) {
             NameParser parser = root.getNameParser("");
             Name newName = parser.parse(contextName);
             newName.add(oldBinding.getName());

src/java.naming/share/classes/com/sun/jndi/toolkit/url/GenericURLContext.java

@@ -476,9 +476,9 @@ abstract public class GenericURLContext implements Context {
 
     public String composeName(String name, String prefix)
         throws NamingException {
-            if (prefix.equals("")) {
+            if (prefix.isEmpty()) {
                 return name;
-            } else if (name.equals("")) {
+            } else if (name.isEmpty()) {
                 return prefix;
             } else {
                 return (prefix + "/" + name);

src/java.net.http/share/classes/jdk/internal/net/http/Http1Request.java

@@ -201,13 +201,13 @@ class Http1Request {
     private String getPathAndQuery(URI uri) {
         String path = uri.getRawPath();
         String query = uri.getRawQuery();
-        if (path == null || path.equals("")) {
+        if (path == null || path.isEmpty()) {
             path = "/";
         }
         if (query == null) {
             query = "";
         }
-        if (query.equals("")) {
+        if (query.isEmpty()) {
             return Utils.encode(path);
         } else {
             return Utils.encode(path + "?" + query);

src/java.net.http/share/classes/jdk/internal/net/http/HttpRequestBuilderImpl.java

@@ -190,7 +190,7 @@ public class HttpRequestBuilderImpl implements HttpRequest.Builder {
     @Override
     public HttpRequest.Builder method(String method, BodyPublisher body) {
         requireNonNull(method);
-        if (method.equals(""))
+        if (method.isEmpty())
             throw newIAE("illegal method <empty string>");
         if (method.equals("CONNECT"))
             throw newIAE("method CONNECT is not supported");
@@ -205,7 +205,7 @@ public class HttpRequestBuilderImpl implements HttpRequest.Builder {
 
     private HttpRequest.Builder method0(String method, BodyPublisher body) {
         assert method != null;
-        assert !method.equals("");
+        assert !method.isEmpty();
         this.method = method;
         this.bodyPublisher = body;
         return this;

src/java.net.http/share/classes/jdk/internal/net/http/ResponseContent.java

@@ -84,7 +84,7 @@ class ResponseContent {
         if (contentLength == -1) {
             String tc = headers.firstValue("Transfer-Encoding")
                                .orElse("");
-            if (!tc.equals("")) {
+            if (!tc.isEmpty()) {
                 if (tc.equalsIgnoreCase("chunked")) {
                     chunkedContent = true;
                 } else {

src/java.net.http/share/classes/jdk/internal/net/http/common/SSLFlowDelegate.java

@@ -97,7 +97,7 @@ public class SSLFlowDelegate {
     private static final ByteBuffer NOTHING = ByteBuffer.allocate(0);
     private static final String monProp = Utils.getProperty("jdk.internal.httpclient.monitorFlowDelegate");
     private static final boolean isMonitored =
-            monProp != null && (monProp.equals("") || monProp.equalsIgnoreCase("true"));
+            monProp != null && (monProp.isEmpty() || monProp.equalsIgnoreCase("true"));
 
     final Executor exec;
     final Reader reader;

src/java.prefs/share/classes/java/util/prefs/AbstractPreferences.java

@@ -203,7 +203,7 @@ public abstract class AbstractPreferences extends Preferences {
      */
     protected AbstractPreferences(AbstractPreferences parent, String name) {
         if (parent==null) {
-            if (!name.equals(""))
+            if (!name.isEmpty())
                 throw new IllegalArgumentException("Root name '"+name+
                                                    "' must be \"\"");
             this.absolutePath = "/";
@@ -212,7 +212,7 @@ public abstract class AbstractPreferences extends Preferences {
             if (name.indexOf('/') != -1)
                 throw new IllegalArgumentException("Name '" + name +
                                                  "' contains '/'");
-            if (name.equals(""))
+            if (name.isEmpty())
               throw new IllegalArgumentException("Illegal name: empty string");
 
             root = parent.root;
@@ -848,7 +848,7 @@ public abstract class AbstractPreferences extends Preferences {
         synchronized(lock) {
             if (removed)
                 throw new IllegalStateException("Node has been removed.");
-            if (path.equals(""))
+            if (path.isEmpty())
                 return this;
             if (path.equals("/"))
                 return root;
@@ -911,7 +911,7 @@ public abstract class AbstractPreferences extends Preferences {
         throws BackingStoreException
     {
         synchronized(lock) {
-            if (path.equals(""))
+            if (path.isEmpty())
                 return !removed;
             if (removed)
                 throw new IllegalStateException("Node has been removed.");

src/java.rmi/share/classes/com/sun/rmi/rmid/ExecOptionPermission.java

@@ -189,7 +189,7 @@ public final class ExecOptionPermission extends Permission
         if (name == null)
             throw new NullPointerException("name can't be null");
 
-        if (name.equals("")) {
+        if (name.isEmpty()) {
             throw new IllegalArgumentException("name can't be empty");
         }
 

src/java.rmi/share/classes/java/rmi/Naming.java

@@ -199,7 +199,7 @@ public final class Naming {
         Registry registry = getRegistry(parsed);
 
         String prefix = "";
-        if (parsed.port > 0 || !parsed.host.equals(""))
+        if (parsed.port > 0 || !parsed.host.isEmpty())
             prefix += "//" + parsed.host;
         if (parsed.port > 0)
             prefix += ":" + parsed.port;

src/java.rmi/share/classes/sun/rmi/server/ActivatableRef.java

@@ -370,7 +370,7 @@ public class ActivatableRef implements RemoteRef {
         ref = null;
         String className = in.readUTF();
 
-        if (className.equals("")) return;
+        if (className.isEmpty()) return;
 
         try {
             Class<?> refClass = Class.forName(RemoteRef.packagePrefix + "." +

src/java.rmi/share/classes/sun/rmi/server/Activation.java

@@ -1857,7 +1857,7 @@ public class Activation implements Serializable {
                         checkPermission(perms,
                             new ExecOptionPermission(option));
                     } catch (AccessControlException e) {
-                        if (value.equals("")) {
+                        if (value.isEmpty()) {
                             checkPermission(perms,
                                 new ExecOptionPermission("-D" + name));
                         } else {
@@ -2101,7 +2101,7 @@ public class Activation implements Serializable {
              * Initialize method for activation exec policy.
              */
             if (!execPolicyClassName.equals("none")) {
-                if (execPolicyClassName.equals("") ||
+                if (execPolicyClassName.isEmpty() ||
                     execPolicyClassName.equals("default"))
                 {
                     execPolicyClassName = DefaultExecPolicy.class.getName();

src/java.rmi/share/classes/sun/rmi/transport/tcp/TCPEndpoint.java

@@ -738,7 +738,7 @@ public class TCPEndpoint implements Endpoint {
                 }
                 hostName = f.getHost();
 
-                if ((hostName == null) || (hostName.equals(""))
+                if ((hostName == null) || (hostName.isEmpty())
                     || (hostName.indexOf('.') < 0 )) {
 
                     hostName = hostAddress;

src/java.scripting/share/classes/com/sun/tools/script/shell/Main.java

@@ -114,7 +114,7 @@ public class Main {
                     System.setProperty(value.substring(0, eq),
                             value.substring(eq + 1));
                 } else {
-                    if (!value.equals("")) {
+                    if (!value.isEmpty()) {
                         System.setProperty(value, "");
                     } else {
                         // do not allow empty property name

src/java.sql.rowset/share/classes/com/sun/rowset/CachedRowSetImpl.java

@@ -593,7 +593,7 @@ public class CachedRowSetImpl extends BaseRowSet implements RowSet, RowSetIntern
 
         super.setCommand(cmd);
 
-        if(!buildTableName(cmd).equals("")) {
+        if(!buildTableName(cmd).isEmpty()) {
             this.setTableName(buildTableName(cmd));
         }
     }
@@ -7069,7 +7069,7 @@ public class CachedRowSetImpl extends BaseRowSet implements RowSet, RowSetIntern
     public void setMatchColumn(String[] columnNames) throws SQLException {
 
         for(int j = 0; j < columnNames.length; j++) {
-           if( columnNames[j] == null || columnNames[j].equals("")) {
+           if( columnNames[j] == null || columnNames[j].isEmpty()) {
               throw new SQLException(resBundle.handleGetObject("cachedrowsetimpl.matchcols2").toString());
            }
         }
@@ -7124,7 +7124,7 @@ public class CachedRowSetImpl extends BaseRowSet implements RowSet, RowSetIntern
      */
     public void setMatchColumn(String columnName) throws SQLException {
         // validate, if col is ok to be set
-        if(columnName == null || (columnName= columnName.trim()).equals("") ) {
+        if(columnName == null || (columnName= columnName.trim()).isEmpty() ) {
             throw new SQLException(resBundle.handleGetObject("cachedrowsetimpl.matchcols2").toString());
         } else {
             // set strMatchColumn

src/java.sql.rowset/share/classes/com/sun/rowset/JdbcRowSetImpl.java

@@ -624,7 +624,7 @@ public class JdbcRowSetImpl extends BaseRowSet implements JdbcRowSet, Joinable {
                     (getDataSourceName());
                 //return ds.getConnection(getUsername(),getPassword());
 
-                if(getUsername() != null && !getUsername().equals("")) {
+                if(getUsername() != null && !getUsername().isEmpty()) {
                      return ds.getConnection(getUsername(),getPassword());
                 } else {
                      return ds.getConnection();
@@ -3873,7 +3873,7 @@ public class JdbcRowSetImpl extends BaseRowSet implements JdbcRowSet, Joinable {
     public void setMatchColumn(String[] columnNames) throws SQLException {
 
         for(int j = 0; j < columnNames.length; j++) {
-           if( columnNames[j] == null || columnNames[j].equals("")) {
+           if( columnNames[j] == null || columnNames[j].isEmpty()) {
               throw new SQLException(resBundle.handleGetObject("jdbcrowsetimpl.matchcols2").toString());
            }
         }
@@ -3928,7 +3928,7 @@ public class JdbcRowSetImpl extends BaseRowSet implements JdbcRowSet, Joinable {
      */
     public void setMatchColumn(String columnName) throws SQLException {
         // validate, if col is ok to be set
-        if(columnName == null || (columnName= columnName.trim()).equals("")) {
+        if(columnName == null || (columnName= columnName.trim()).isEmpty()) {
             throw new SQLException(resBundle.handleGetObject("jdbcrowsetimpl.matchcols2").toString());
         } else {
             // set strMatchColumn

src/java.sql.rowset/share/classes/com/sun/rowset/internal/WebRowSetXmlWriter.java

@@ -537,7 +537,7 @@ public class WebRowSetXmlWriter implements XmlWriter, Serializable {
     private void writeStringData(String s) throws java.io.IOException {
         if (s == null) {
             writeNull();
-        } else if (s.equals("")) {
+        } else if (s.isEmpty()) {
             writeEmptyString();
         } else {
 

src/java.sql.rowset/share/classes/javax/sql/rowset/BaseRowSet.java

@@ -852,7 +852,7 @@ public abstract class BaseRowSet implements Serializable, Cloneable {
 
         if (name == null) {
             dataSource = null;
-        } else if (name.equals("")) {
+        } else if (name.isEmpty()) {
            throw new SQLException("DataSource name cannot be empty string");
         } else {
            dataSource = name;

src/java.sql/share/classes/java/sql/DriverManager.java

@@ -622,7 +622,7 @@ public class DriverManager {
 
             println("DriverManager.initialize: jdbc.drivers = " + drivers);
 
-            if (drivers != null && !drivers.equals("")) {
+            if (drivers != null && !drivers.isEmpty()) {
                 String[] driversList = drivers.split(":");
                 println("number of Drivers:" + driversList.length);
                 for (String aDriver : driversList) {

src/java.xml/share/classes/com/sun/xml/internal/stream/events/AttributeImpl.java

@@ -85,7 +85,7 @@ public class AttributeImpl extends DummyEvent implements Attribute
         init();
         fQName = qname ;
         fValue = value ;
-        if(type != null && !type.equals(""))
+        if(type != null && !type.isEmpty())
             fAttributeType = type;
 
         fNonNormalizedvalue = nonNormalizedvalue;

src/java.xml/share/classes/com/sun/xml/internal/stream/events/StartDocumentEvent.java

@@ -73,7 +73,7 @@ implements StartDocument {
         this.fEncodingScheam = encoding;
         this.fVersion = version;
         this.fStandalone = standalone;
-        if (encoding != null && !encoding.equals(""))
+        if (encoding != null && !encoding.isEmpty())
             this.fEncodingSchemeSet = true;
         else {
             this.fEncodingSchemeSet = false;

src/java.xml/share/classes/com/sun/xml/internal/stream/writers/XMLDOMWriterImpl.java

@@ -219,7 +219,7 @@ public class XMLDOMWriterImpl implements XMLStreamWriterBase  {
             }
 
             String qualifiedName = null;
-            if(prefix.equals("")){
+            if(prefix.isEmpty()){
                 qualifiedName = localName;
             }else{
                 qualifiedName = getQName(prefix,localName);
@@ -254,7 +254,7 @@ public class XMLDOMWriterImpl implements XMLStreamWriterBase  {
                 throw new XMLStreamException("prefix cannot be null");
             }
             String qualifiedName = null;
-            if(prefix.equals("")){
+            if(prefix.isEmpty()){
                 qualifiedName = localName;
             }else{
 
@@ -502,7 +502,7 @@ public class XMLDOMWriterImpl implements XMLStreamWriterBase  {
 
         String qname = null;
 
-        if (prefix.equals("")) {
+        if (prefix.isEmpty()) {
             qname = XMLConstants.XMLNS_ATTRIBUTE;
         } else {
             qname = getQName(XMLConstants.XMLNS_ATTRIBUTE,prefix);
@@ -669,7 +669,7 @@ public class XMLDOMWriterImpl implements XMLStreamWriterBase  {
                 throw new XMLStreamException("Prefix cannot be null");
             }
 
-            if(prefix.equals("")){
+            if(prefix.isEmpty()){
                 qname = localName;
             }else{
                 qname = getQName(prefix,localName);

src/java.xml/share/classes/com/sun/xml/internal/stream/writers/XMLStreamWriterImpl.java

@@ -628,8 +628,8 @@ public final class XMLStreamWriterImpl extends AbstractMap<Object, Object>
             }
 
             if (!fIsRepairingNamespace) {
-                if (prefix == null || prefix.equals("")){
+                if (prefix == null || prefix.isEmpty()){
-                    if (!namespaceURI.equals("")) {
+                    if (!namespaceURI.isEmpty()) {
                         throw new XMLStreamException("prefix cannot be null or empty");
                     } else {
                         writeAttributeWithPrefix(null, localName, value);
@@ -908,7 +908,7 @@ public final class XMLStreamWriterImpl extends AbstractMap<Object, Object>
                 } else {
                     fWriter.write(OPEN_END_TAG);
 
-                    if ((elem.prefix != null) && !(elem.prefix).equals("")) {
+                    if ((elem.prefix != null) && !(elem.prefix).isEmpty()) {
                         fWriter.write(elem.prefix);
                         fWriter.write(":");
                     }
@@ -945,7 +945,7 @@ public final class XMLStreamWriterImpl extends AbstractMap<Object, Object>
             fWriter.write(OPEN_END_TAG);
 
             if ((currentElement.prefix != null) &&
-                    !(currentElement.prefix).equals("")) {
+                    !(currentElement.prefix).isEmpty()) {
                 fWriter.write(currentElement.prefix);
                 fWriter.write(":");
             }
@@ -1180,19 +1180,19 @@ public final class XMLStreamWriterImpl extends AbstractMap<Object, Object>
             }
 
             // Verify the encoding before writing anything
-            if (encoding != null && !encoding.equals("")) {
+            if (encoding != null && !encoding.isEmpty()) {
                 verifyEncoding(encoding);
             }
 
             fWriter.write("<?xml version=\"");
 
-            if ((version == null) || version.equals("")) {
+            if ((version == null) || version.isEmpty()) {
                 fWriter.write(DEFAULT_XML_VERSION);
             } else {
                 fWriter.write(version);
             }
 
-            if (encoding != null && !encoding.equals("")) {
+            if (encoding != null && !encoding.isEmpty()) {
                 fWriter.write("\" encoding=\"");
                 fWriter.write(encoding);
             }
@@ -1584,7 +1584,7 @@ public final class XMLStreamWriterImpl extends AbstractMap<Object, Object>
                     attr = fAttributeCache.get(j);
 
                     if ((attr.prefix != null) && (attr.uri != null)) {
-                        if (!attr.prefix.equals("") && !attr.uri.equals("") ) {
+                        if (!attr.prefix.isEmpty() && !attr.uri.isEmpty() ) {
                             String tmp = fInternalNamespaceContext.getPrefix(attr.uri);
 
                             if ((tmp == null) || (!tmp.equals(attr.prefix))) {
@@ -1765,7 +1765,7 @@ public final class XMLStreamWriterImpl extends AbstractMap<Object, Object>
 
         for(int i=0 ; i< fAttributeCache.size();i++){
             attr = fAttributeCache.get(i);
-            if((attr.prefix != null && !attr.prefix.equals("")) || (attr.uri != null && !attr.uri.equals(""))) {
+            if((attr.prefix != null && !attr.prefix.isEmpty()) || (attr.uri != null && !attr.uri.isEmpty())) {
                 correctPrefix(currentElement,attr);
             }
         }
@@ -1773,7 +1773,7 @@ public final class XMLStreamWriterImpl extends AbstractMap<Object, Object>
         if (!isDeclared(currentElement)) {
             if ((currentElement.prefix != null) &&
                     (currentElement.uri != null)) {
-                if ((!currentElement.prefix.equals("")) && (!currentElement.uri.equals(""))) {
+                if ((!currentElement.prefix.isEmpty()) && (!currentElement.uri.isEmpty())) {
                     fNamespaceDecls.add(currentElement);
                 }
             }
@@ -1798,7 +1798,7 @@ public final class XMLStreamWriterImpl extends AbstractMap<Object, Object>
             /* If 'attr' is an attribute and it is in no namespace(which means that prefix="", uri=""), attr's
                namespace should not be redinded. See [http://www.w3.org/TR/REC-xml-names/#defaulting].
              */
-            if (attr.prefix != null && attr.prefix.equals("") && attr.uri != null && attr.uri.equals("")){
+            if (attr.prefix != null && attr.prefix.isEmpty() && attr.uri != null && attr.uri.isEmpty()){
                 repairNamespaceDecl(attr);
             }
         }

src/java.xml/share/classes/javax/xml/catalog/CatalogFeatures.java

@@ -619,13 +619,13 @@ public class CatalogFeatures {
     private boolean getSystemProperty(Feature cf, String sysPropertyName) {
         if (cf.hasSystemProperty()) {
             String value = SecuritySupport.getSystemProperty(sysPropertyName);
-            if (value != null && !value.equals("")) {
+            if (value != null && !value.isEmpty()) {
                 setProperty(cf, State.SYSTEMPROPERTY, value);
                 return true;
             }
 
             value = SecuritySupport.readJAXPProperty(sysPropertyName);
-            if (value != null && !value.equals("")) {
+            if (value != null && !value.isEmpty()) {
                 setProperty(cf, State.JAXPDOTPROPERTIES, value);
                 return true;
             }

src/java.xml/share/classes/javax/xml/catalog/Util.java

@@ -221,7 +221,7 @@ class Util {
      */
     static String[] getCatalogFiles(String sysPropertyName) {
         String value = SecuritySupport.getJAXPSystemProperty(sysPropertyName);
-        if (value != null && !value.equals("")) {
+        if (value != null && !value.isEmpty()) {
             return value.split(";");
         }
         return null;

src/java.xml/share/classes/jdk/xml/internal/JdkXmlFeatures.java

@@ -383,13 +383,13 @@ public class JdkXmlFeatures {
     private boolean getSystemProperty(XmlFeature feature, String sysPropertyName) {
         try {
             String value = SecuritySupport.getSystemProperty(sysPropertyName);
-            if (value != null && !value.equals("")) {
+            if (value != null && !value.isEmpty()) {
                 setFeature(feature, State.SYSTEMPROPERTY, Boolean.parseBoolean(value));
                 return true;
             }
 
             value = SecuritySupport.readJAXPProperty(sysPropertyName);
-            if (value != null && !value.equals("")) {
+            if (value != null && !value.isEmpty()) {
                 setFeature(feature, State.JAXPDOTPROPERTIES, Boolean.parseBoolean(value));
                 return true;
             }

src/jdk.jartool/share/classes/sun/tools/jar/Main.java

@@ -1180,7 +1180,7 @@ public class Main {
         String name = entry.name;
         boolean isDir = entry.isDir;
 
-        if (name.equals("") || name.equals(".") || name.equals(zname)) {
+        if (name.isEmpty() || name.equals(".") || name.equals(zname)) {
             return;
         } else if ((name.equals(MANIFEST_DIR) || name.equals(MANIFEST_NAME))
                    && !Mflag) {
@@ -1886,7 +1886,7 @@ public class Main {
                 .map(ModuleInfoEntry::name)
                 .map(Main::versionFromEntryName)
                 .collect(joining(" "));
-        if (!releases.equals(""))
+        if (!releases.isEmpty())
             output("releases: " + releases + "\n");
 
         // Describe the operative descriptor for the specified --release, if any
@@ -1955,7 +1955,7 @@ public class Main {
 
         sb.append(md.toNameAndVersion());
 
-        if (!uriString.equals(""))
+        if (!uriString.isEmpty())
             sb.append(" ").append(uriString);
         if (md.isOpen())
             sb.append(" open");

src/jdk.javadoc/share/classes/com/sun/tools/javadoc/main/ClassDocImpl.java

@@ -420,7 +420,7 @@ public class ClassDocImpl extends ProgramElementDocImpl implements ClassDoc {
         } else {
             String n = "";
             for ( ; c != null; c = c.owner.enclClass()) {
-                n = c.name + (n.equals("") ? "" : ".") + n;
+                n = c.name + (n.isEmpty() ? "" : ".") + n;
             }
             return n;
         }

src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/SearchIndexItem.java

@@ -114,18 +114,18 @@ public class SearchIndexItem {
                 item.append("\"m\":\"").append(containingModule).append("\",");
             }
             item.append("\"l\":\"").append(label).append("\"");
-            if (!url.equals("")) {
+            if (!url.isEmpty()) {
                 item.append(",\"url\":\"").append(url).append("\"");
             }
             item.append("}");
             break;
         case TYPES:
             item.append("{");
-            if (!containingPackage.equals("")) {
+            if (!containingPackage.isEmpty()) {
                 item.append("\"p\":\"").append(containingPackage).append("\",");
             }
             item.append("\"l\":\"").append(label).append("\"");
-            if (!url.equals("")) {
+            if (!url.isEmpty()) {
                 item.append(",\"url\":\"").append(url).append("\"");
             }
             item.append("}");
@@ -135,7 +135,7 @@ public class SearchIndexItem {
                     .append("\"p\":\"").append(containingPackage).append("\",")
                     .append("\"c\":\"").append(containingClass).append("\",")
                     .append("\"l\":\"").append(label).append("\"");
-            if (!url.equals("")) {
+            if (!url.isEmpty()) {
                 item.append(",\"url\":\"").append(url).append("\"");
             }
             item.append("}");
@@ -144,7 +144,7 @@ public class SearchIndexItem {
             item.append("{")
                     .append("\"l\":\"").append(label).append("\",")
                     .append("\"h\":\"").append(holder).append("\",");
-            if (!description.equals("")) {
+            if (!description.isEmpty()) {
                 item.append("\"d\":\"").append(description).append("\",");
             }
             item.append("\"u\":\"").append(url).append("\"")

src/jdk.jcmd/share/classes/sun/tools/jmap/JMap.java

@@ -149,7 +149,7 @@ public class JMap {
         throws AttachNotSupportedException, IOException,
                UnsupportedEncodingException {
         String liveopt = "-all";
-        if (options.equals("") || options.equals("all")) {
+        if (options.isEmpty() || options.equals("all")) {
             //  pass
         }
         else if (options.equals("live")) {

src/jdk.jconsole/share/classes/sun/tools/jconsole/ConnectDialog.java

@@ -313,9 +313,9 @@ public class ConnectDialog extends InternalDialog
                 if (remoteRadioButton.isSelected()) {
                     String txt = remoteTF.getText().trim();
                     String userName = userNameTF.getText().trim();
-                    userName = userName.equals("") ? null : userName;
+                    userName = userName.isEmpty() ? null : userName;
                     String password = passwordTF.getText();
-                    password = password.equals("") ? null : password;
+                    password = password.isEmpty() ? null : password;
                     try {
                         if (txt.startsWith(JConsole.ROOT_URL)) {
                             String url = txt;

src/jdk.jconsole/share/classes/sun/tools/jconsole/ThreadTab.java

@@ -665,7 +665,7 @@ class ThreadTab extends Tab implements ActionListener, DocumentListener, ListSel
         }
 
         public void focusLost(FocusEvent e) {
-            if (promptRemoved && getText().equals("")) {
+            if (promptRemoved && getText().isEmpty()) {
                 setText(prompt);
                 setForeground(Color.gray);
                 promptRemoved = false;

src/jdk.management.agent/share/classes/jdk/internal/agent/Agent.java

@@ -265,7 +265,7 @@ public class Agent {
     // return empty property set
     private static Properties parseString(String args) {
         Properties argProps = new Properties();
-        if (args != null && !args.trim().equals("")) {
+        if (args != null && !args.trim().isEmpty()) {
             for (String option : args.split(",")) {
                 String s[] = option.split("=", 2);
                 String name = s[0].trim();

src/jdk.naming.dns/share/classes/com/sun/jndi/dns/DnsContext.java

@@ -537,8 +537,8 @@ public class DnsContext extends ComponentDirContext {
         int prefixLast = prefixC.size() - 1;
 
         // Let toolkit do the work at namespace boundaries.
-        if (nameC.isEmpty() || nameC.get(0).equals("") ||
+        if (nameC.isEmpty() || nameC.get(0).isEmpty() ||
-                prefixC.isEmpty() || prefixC.get(prefixLast).equals("")) {
+                prefixC.isEmpty() || prefixC.get(prefixLast).isEmpty()) {
             return super.composeName(nameC, prefixC);
         }
 
@@ -687,7 +687,7 @@ public class DnsContext extends ComponentDirContext {
     private static CT fromAttrId(String attrId)
             throws InvalidAttributeIdentifierException {
 
-        if (attrId.equals("")) {
+        if (attrId.isEmpty()) {
             throw new InvalidAttributeIdentifierException(
                     "Attribute ID cannot be empty");
         }

src/jdk.naming.dns/share/classes/com/sun/jndi/dns/DnsName.java

@@ -368,7 +368,7 @@ public final class DnsName implements Name {
 
     boolean hasRootLabel() {
         return (!isEmpty() &&
-                get(0).equals(""));
+                get(0).isEmpty());
     }
 
     /*
@@ -442,7 +442,7 @@ public final class DnsName implements Name {
         // label of the name.  Those two are special cases in that for
         // all other domain names, the number of labels is one greater
         // than the number of dot separators.
-        if (!name.equals("") && !name.equals(".")) {
+        if (!name.isEmpty() && !name.equals(".")) {
             add(0, label.toString());
         }
 

src/jdk.naming.dns/share/classes/com/sun/jndi/dns/DnsUrl.java

@@ -89,7 +89,7 @@ public class DnsUrl extends Uri {
         domain = path.startsWith("/")
             ? path.substring(1)
             : path;
-        domain = domain.equals("")
+        domain = domain.isEmpty()
             ? "."
             : UrlUtil.decode(domain);
 

src/jdk.naming.dns/share/classes/com/sun/jndi/dns/ResourceRecord.java

@@ -200,7 +200,7 @@ public class ResourceRecord {
     }
 
     private static int nameToValue(String name, String[] names) {
-        if (name.equals("")) {
+        if (name.isEmpty()) {
             return -1;                          // invalid name
         } else if (name.equals("*")) {
             return QTYPE_STAR;                  // QTYPE_STAR == QCLASS_STAR

src/jdk.naming.dns/share/classes/com/sun/jndi/dns/ZoneNode.java

@@ -124,7 +124,7 @@ class ZoneNode extends NameNode {
      * name and its resource records.  Returns the zone's new contents.
      */
     NameNode populate(DnsName zone, ResourceRecords rrs) {
-        // assert zone.get(0).equals("");               // zone has root label
+        // assert zone.get(0).isEmpty();               // zone has root label
         // assert (zone.size() == (depth() + 1));       // +1 due to root label
 
         NameNode newContents = new NameNode(null);

src/jdk.rmic/share/classes/sun/tools/java/ClassPath.java

@@ -230,7 +230,7 @@ class ClassPath {
             int i = name.lastIndexOf(File.separatorChar);
             subdir = name.substring(0, i + 1);
             basename = name.substring(i + 1);
-        } else if (!subdir.equals("")
+        } else if (!subdir.isEmpty()
                    && !subdir.endsWith(fileSeparatorChar)) {
             // zip files are picky about "foo" vs. "foo/".
             // also, the getFiles caches are keyed with a trailing /

src/jdk.rmic/share/classes/sun/tools/java/Package.java

@@ -115,7 +115,7 @@ class Package {
     }
 
     private String makeName(String fileName) {
-        return pkg.equals("") ? fileName : pkg + File.separator + fileName;
+        return pkg.isEmpty() ? fileName : pkg + File.separator + fileName;
     }
 
     /**
@@ -153,7 +153,7 @@ class Package {
     }
 
     public String toString() {
-        if (pkg.equals("")) {
+        if (pkg.isEmpty()) {
             return "unnamed package";
         }
         return "package " + pkg;