8080522: Optimize string operations in java.base/share/classes/sun/security/x509/

Reviewed-by: mullan

jdk/src/java.base/share/classes/sun/security/x509/AVA.java

@@ -454,7 +454,7 @@ public class AVA implements DerEncoder {
             if (embeddedHex.size() > 0) {
                 // add space(s) before embedded hex bytes
                 for (int i = 0; i < spaceCount; i++) {
-                    temp.append(" ");
+                    temp.append(' ');
                 }
                 spaceCount = 0;
 
@@ -472,7 +472,7 @@ public class AVA implements DerEncoder {
             } else {
                 // add space(s)
                 for (int i = 0; i < spaceCount; i++) {
-                    temp.append(" ");
+                    temp.append(' ');
                 }
                 spaceCount = 0;
                 temp.append((char)c);
@@ -853,7 +853,7 @@ public class AVA implements DerEncoder {
                 }
                 sbuffer.append(c);
             }
-            typeAndValue.append(sbuffer.toString());
+            typeAndValue.append(sbuffer);
         }
         return typeAndValue.toString();
     }
@@ -1039,7 +1039,7 @@ public class AVA implements DerEncoder {
         StringBuilder   retval = new StringBuilder(40);
 
         retval.append(keyword);
-        retval.append("=");
+        retval.append('=');
 
         try {
             String valStr = value.getAsString();
@@ -1147,9 +1147,11 @@ public class AVA implements DerEncoder {
                 // Emit the string ... quote it if needed
                 // if string is already quoted, don't re-quote
                 if (!alreadyQuoted && quoteNeeded) {
-                    retval.append("\"" + sbuffer.toString() + "\"");
+                    retval.append('\"')
+                        .append(sbuffer)
+                        .append('\"');
                 } else {
-                    retval.append(sbuffer.toString());
+                    retval.append(sbuffer);
                 }
             }
         } catch (IOException e) {

jdk/src/java.base/share/classes/sun/security/x509/AuthorityKeyIdentifierExtension.java

@@ -196,17 +196,20 @@ implements CertAttrSet<String> {
      * Return the object as a string.
      */
     public String toString() {
-        String s = super.toString() + "AuthorityKeyIdentifier [\n";
+        StringBuilder sb = new StringBuilder();
+        sb.append(super.toString())
+            .append("AuthorityKeyIdentifier [\n");
         if (id != null) {
-            s += id.toString();     // id already has a newline
+            sb.append(id);       // id already has a newline
         }
         if (names != null) {
-            s += names.toString() + "\n";
+            sb.append(names).append('\n');
         }
         if (serialNum != null) {
-            s += serialNum.toString() + "\n";
+            sb.append(serialNum).append('\n');
         }
-        return (s + "]\n");
+        sb.append("]\n");
+        return sb.toString();
     }
 
     /**

jdk/src/java.base/share/classes/sun/security/x509/BasicConstraintsExtension.java

@@ -171,15 +171,11 @@ implements CertAttrSet<String> {
       * Return user readable form of extension.
       */
      public String toString() {
-         String s = super.toString() + "BasicConstraints:[\n";
+         return super.toString() +
-
+             "BasicConstraints:[\n  CA:" + ca +
-         s += ((ca) ? ("  CA:true") : ("  CA:false")) + "\n";
+             "\n  PathLen:" +
-         if (pathLen >= 0) {
+             ((pathLen >= 0) ? String.valueOf(pathLen) : " undefined") +
-             s += "  PathLen:" + pathLen + "\n";
+             "\n]\n";
-         } else {
-             s += "  PathLen: undefined\n";
-         }
-         return (s + "]\n");
      }
 
      /**

jdk/src/java.base/share/classes/sun/security/x509/CRLDistributionPointsExtension.java

@@ -231,8 +231,8 @@ public class CRLDistributionPointsExtension extends Extension
             distributionPoints = (List<DistributionPoint>)obj;
         } else {
             throw new IOException("Attribute name [" + name +
-                                "] not recognized by " +
+                                  "] not recognized by " +
-                                "CertAttrSet:" + extensionName + ".");
+                                  "CertAttrSet:" + extensionName + '.');
         }
         encodeThis();
     }
@@ -245,8 +245,8 @@ public class CRLDistributionPointsExtension extends Extension
             return distributionPoints;
         } else {
             throw new IOException("Attribute name [" + name +
-                                "] not recognized by " +
+                                  "] not recognized by " +
-                                "CertAttrSet:" + extensionName + ".");
+                                  "CertAttrSet:" + extensionName + '.');
         }
     }
 

jdk/src/java.base/share/classes/sun/security/x509/CRLNumberExtension.java

@@ -146,8 +146,8 @@ implements CertAttrSet<String> {
             }
             crlNumber = (BigInteger)obj;
         } else {
-          throw new IOException("Attribute name not recognized by"
+            throw new IOException("Attribute name not recognized by" +
-                                + " CertAttrSet:" + extensionName + ".");
+                                  " CertAttrSet:" + extensionName + '.');
         }
         encodeThis();
     }
@@ -172,8 +172,8 @@ implements CertAttrSet<String> {
         if (name.equalsIgnoreCase(NUMBER)) {
             crlNumber = null;
         } else {
-          throw new IOException("Attribute name not recognized by"
+            throw new IOException("Attribute name not recognized by" +
-                                + " CertAttrSet:" + extensionName + ".");
+                                  " CertAttrSet:" + extensionName + '.');
         }
         encodeThis();
     }
@@ -182,10 +182,15 @@ implements CertAttrSet<String> {
      * Returns a printable representation of the CRLNumberExtension.
      */
     public String toString() {
-        String s = super.toString() + extensionLabel + ": " +
+        StringBuilder sb = new StringBuilder();
-                   ((crlNumber == null) ? "" : Debug.toHexString(crlNumber))
+        sb.append(super.toString())
-                   + "\n";
+            .append(extensionLabel)
-        return (s);
+            .append(": ");
+        if (crlNumber != null) {
+            sb.append(Debug.toHexString(crlNumber));
+        }
+        sb.append('\n');
+        return sb.toString();
     }
 
     /**
@@ -195,7 +200,7 @@ implements CertAttrSet<String> {
      * @exception IOException on encoding errors.
      */
     public void encode(OutputStream out) throws IOException {
-       DerOutputStream  tmp = new DerOutputStream();
+        DerOutputStream tmp = new DerOutputStream();
         encode(out, PKIXExtensions.CRLNumber_Id, true);
     }
 

jdk/src/java.base/share/classes/sun/security/x509/CertException.java

@@ -158,7 +158,7 @@ public class CertException extends SecurityException {
      */
     public String toString()
     {
-        return "[Certificate Exception: " + getMessage() + "]";
+        return "[Certificate Exception: " + getMessage() + ']';
     }
 
     /**
@@ -168,6 +168,6 @@ public class CertException extends SecurityException {
     {
         return getVerfDescription()
                 + ( (moreData != null)
-                    ? ( "\n  (" + moreData + ")" ) : "" );
+                    ? ( "\n  (" + moreData + ')' ) : "" );
     }
 }

jdk/src/java.base/share/classes/sun/security/x509/CertificatePoliciesExtension.java

@@ -160,10 +160,12 @@ implements CertAttrSet<String> {
         if (certPolicies == null) {
             return "";
         }
-        StringBuilder sb = new StringBuilder(super.toString());
+
-        sb.append("CertificatePolicies [\n");
+        StringBuilder sb = new StringBuilder();
+        sb.append(super.toString())
+            .append("CertificatePolicies [\n");
         for (PolicyInformation info : certPolicies) {
-            sb.append(info.toString());
+            sb.append(info);
         }
         sb.append("]\n");
         return sb.toString();

jdk/src/java.base/share/classes/sun/security/x509/CertificateValidity.java

@@ -134,8 +134,8 @@ public class CertificateValidity implements CertAttrSet<String> {
     public String toString() {
         if (notBefore == null || notAfter == null)
             return "";
-        return ("Validity: [From: " + notBefore.toString() +
+        return "Validity: [From: " + notBefore +
-             ",\n               To: " + notAfter.toString() + "]");
+               ",\n               To: " + notAfter + ']';
     }
 
     /**

jdk/src/java.base/share/classes/sun/security/x509/DistributionPoint.java

@@ -380,23 +380,29 @@ public class DistributionPoint {
      */
     public String toString() {
         StringBuilder sb = new StringBuilder();
+        sb.append("DistributionPoint:\n     ");
         if (fullName != null) {
-            sb.append("DistributionPoint:\n     " + fullName + "\n");
+            sb.append(fullName);
         }
         if (relativeName != null) {
-            sb.append("DistributionPoint:\n     " + relativeName + "\n");
+            sb.append(relativeName);
         }
+        sb.append('\n');
 
         if (reasonFlags != null) {
             sb.append("   ReasonFlags:\n");
             for (int i = 0; i < reasonFlags.length; i++) {
                 if (reasonFlags[i]) {
-                    sb.append("    " + reasonToString(i) + "\n");
+                    sb.append("    ")
+                        .append(reasonToString(i))
+                        .append('\n');
                 }
             }
         }
         if (crlIssuer != null) {
-            sb.append("   CRLIssuer:" + crlIssuer + "\n");
+            sb.append("   CRLIssuer:")
+                .append(crlIssuer)
+                .append('\n');
         }
         return sb.toString();
     }

jdk/src/java.base/share/classes/sun/security/x509/DistributionPointName.java

@@ -230,13 +230,13 @@ public class DistributionPointName {
      */
     public String toString() {
         StringBuilder sb = new StringBuilder();
+        sb.append("DistributionPointName:\n     ");
         if (fullName != null) {
-            sb.append("DistributionPointName:\n     " + fullName + "\n");
+            sb.append(fullName);
-
         } else {
-            sb.append("DistributionPointName:\n     " + relativeName + "\n");
+            sb.append(relativeName);
         }
-
+        sb.append('\n');
         return sb.toString();
     }
 }

jdk/src/java.base/share/classes/sun/security/x509/EDIPartyName.java

@@ -209,10 +209,15 @@ public class EDIPartyName implements GeneralNameInterface {
      * Return the printable string.
      */
     public String toString() {
-        return ("EDIPartyName: " +
+        StringBuilder sb = new StringBuilder("EDIPartyName: ");
-                 ((assigner == null) ? "" :
+        if (assigner != null) {
-                   ("  nameAssigner = " + assigner + ","))
+            sb.append("  nameAssigner = ")
-                 + "  partyName = " + party);
+              .append(assigner)
+              .append(',');
+        }
+        sb.append("  partyName = ")
+          .append(party);
+        return sb.toString();
     }
 
     /**

jdk/src/java.base/share/classes/sun/security/x509/Extension.java

@@ -219,13 +219,8 @@ public class Extension implements java.security.cert.Extension {
      * Returns the Extension in user readable form.
      */
     public String toString() {
-        String s = "ObjectId: " + extensionId.toString();
+        return "ObjectId: " + extensionId +
-        if (critical) {
+                " Criticality=" + critical + '\n';
-            s += " Criticality=true\n";
-        } else {
-            s += " Criticality=false\n";
-        }
-        return (s);
     }
 
     // Value to mix up the hash

jdk/src/java.base/share/classes/sun/security/x509/GeneralSubtree.java

@@ -127,15 +127,22 @@ public class GeneralSubtree {
      * Return a printable string of the GeneralSubtree.
      */
     public String toString() {
-        String s = "\n   GeneralSubtree: [\n" +
+        StringBuilder sb = new StringBuilder();
-            "    GeneralName: " + ((name == null) ? "" : name.toString()) +
+        sb.append("\n   GeneralSubtree: [")
-            "\n    Minimum: " + minimum;
+            .append("\n    GeneralName: ");
-            if (maximum == -1) {
+        if (name != null) {
-                s += "\t    Maximum: undefined";
+            sb.append(name);
-            } else
+        }
-                s += "\t    Maximum: " + maximum;
+        sb.append("\n    Minimum: ")
-            s += "    ]\n";
+            .append(minimum)
-        return (s);
+            .append("\n    Maximum: ");
+        if (maximum == -1) {
+            sb.append("undefined");
+        } else {
+            sb.append(maximum);
+        }
+        sb.append("    ]\n");
+        return sb.toString();
     }
 
     /**

jdk/src/java.base/share/classes/sun/security/x509/GeneralSubtrees.java

@@ -124,8 +124,7 @@ public class GeneralSubtrees implements Cloneable {
      * Return a printable string of the GeneralSubtree.
      */
     public String toString() {
-        String s = "   GeneralSubtrees:\n" + trees.toString() + "\n";
+        return "   GeneralSubtrees:\n" + trees + '\n';
-        return s;
     }
 
     /**

jdk/src/java.base/share/classes/sun/security/x509/IPAddressName.java

@@ -263,7 +263,7 @@ public class IPAddressName implements GeneralNameInterface {
             if (address.length == 8) {
                 byte[] mask = new byte[4];
                 System.arraycopy(address, 4, mask, 0, 4);
-                name = name + "/" +
+                name = name + '/' +
                        InetAddress.getByAddress(mask).getHostAddress();
             }
         } else {
@@ -285,7 +285,7 @@ public class IPAddressName implements GeneralNameInterface {
                     if (!ba.get(i))
                         break;
                 }
-                name = name + "/" + i;
+                name = name + '/' + i;
                 // Verify remaining bits 0
                 for (; i < 16*8; i++) {
                     if (ba.get(i)) {

jdk/src/java.base/share/classes/sun/security/x509/IssuerAlternativeNameExtension.java

@@ -140,17 +140,20 @@ extends Extension implements CertAttrSet<String> {
      * Returns a printable representation of the IssuerAlternativeName.
      */
     public String toString() {
-
+        StringBuilder sb = new StringBuilder();
-        String result = super.toString() + "IssuerAlternativeName [\n";
+        sb.append(super.toString())
-        if(names == null) {
+            .append("IssuerAlternativeName [\n");
-            result += "  null\n";
+        if (names == null) {
+            sb.append("  null\n");
         } else {
-            for(GeneralName name: names.names()) {
+            for (GeneralName name : names.names()) {
-                result += "  "+name+"\n";
+                sb.append("  ")
+                    .append(name)
+                    .append('\n');
             }
         }
-        result += "]\n";
+        sb.append("]\n");
-        return result;
+        return sb.toString();
     }
 
     /**

jdk/src/java.base/share/classes/sun/security/x509/IssuingDistributionPointExtension.java

@@ -441,9 +441,9 @@ public class IssuingDistributionPointExtension extends Extension
      * Returns the extension as user readable string.
      */
     public String toString() {
-
+        StringBuilder sb = new StringBuilder();
-        StringBuilder sb = new StringBuilder(super.toString());
+        sb.append(super.toString())
-        sb.append("IssuingDistributionPoint [\n  ");
+            .append("IssuingDistributionPoint [\n  ");
 
         if (distributionPoint != null) {
             sb.append(distributionPoint);
@@ -453,23 +453,18 @@ public class IssuingDistributionPointExtension extends Extension
             sb.append(revocationReasons);
         }
 
-        sb.append((hasOnlyUserCerts)
+        sb.append("  Only contains user certs: ")
-                ? ("  Only contains user certs: true")
+            .append(hasOnlyUserCerts)
-                : ("  Only contains user certs: false")).append("\n");
+            .append('\n')
-
+            .append("  Only contains CA certs: ")
-        sb.append((hasOnlyCACerts)
+            .append(hasOnlyCACerts)
-                ? ("  Only contains CA certs: true")
+            .append('\n')
-                : ("  Only contains CA certs: false")).append("\n");
+            .append("  Only contains attribute certs: ")
-
+            .append(hasOnlyAttributeCerts)
-        sb.append((hasOnlyAttributeCerts)
+            .append('\n')
-                ? ("  Only contains attribute certs: true")
+            .append("  Indirect CRL: ")
-                : ("  Only contains attribute certs: false")).append("\n");
+            .append(isIndirectCRL)
-
+            .append("\n]\n");
-        sb.append((isIndirectCRL)
-                ? ("  Indirect CRL: true")
-                : ("  Indirect CRL: false")).append("\n");
-
-        sb.append("]\n");
 
         return sb.toString();
     }

jdk/src/java.base/share/classes/sun/security/x509/NameConstraintsExtension.java

@@ -214,12 +214,19 @@ implements CertAttrSet<String>, Cloneable {
      * Return the printable string.
      */
     public String toString() {
-        return (super.toString() + "NameConstraints: [" +
+        StringBuilder sb = new StringBuilder();
-                ((permitted == null) ? "" :
+        sb.append(super.toString())
-                     ("\n    Permitted:" + permitted.toString())) +
+            .append("NameConstraints: [");
-                ((excluded == null) ? "" :
+        if (permitted != null) {
-                     ("\n    Excluded:" + excluded.toString()))
+            sb.append("\n    Permitted:")
-                + "   ]\n");
+                .append(permitted);
+        }
+        if (excluded != null) {
+            sb.append("\n    Excluded:")
+                .append(excluded);
+        }
+        sb.append("   ]\n");
+        return sb.toString();
     }
 
     /**

jdk/src/java.base/share/classes/sun/security/x509/PolicyConstraintsExtension.java

@@ -175,19 +175,24 @@ implements CertAttrSet<String> {
      * Return the extension as user readable string.
      */
     public String toString() {
-        String s;
+        StringBuilder sb = new StringBuilder();
-        s = super.toString() + "PolicyConstraints: [" + "  Require: ";
+        sb.append(super.toString())
-        if (require == -1)
+            .append("PolicyConstraints: [")
-            s += "unspecified;";
+            .append("  Require: ");
-        else
+        if (require == -1) {
-            s += require + ";";
+            sb.append("unspecified;");
-        s += "\tInhibit: ";
+        } else {
-        if (inhibit == -1)
+            sb.append(require)
-            s += "unspecified";
+                .append(';');
-        else
+        }
-            s += inhibit;
+        sb.append("\tInhibit: ");
-        s += " ]\n";
+        if (inhibit == -1) {
-        return s;
+            sb.append("unspecified");
+        } else {
+            sb.append(inhibit);
+        }
+        sb.append(" ]\n");
+        return sb.toString();
     }
 
     /**

jdk/src/java.base/share/classes/sun/security/x509/PolicyInformation.java

@@ -258,9 +258,7 @@ public class PolicyInformation {
      * Return a printable representation of the PolicyInformation.
      */
     public String toString() {
-        StringBuilder s = new StringBuilder("  [" + policyIdentifier.toString());
+        return "  [" + policyIdentifier + policyQualifiers + "  ]\n";
-        s.append(policyQualifiers + "  ]\n");
-        return s.toString();
     }
 
     /**

jdk/src/java.base/share/classes/sun/security/x509/PrivateKeyUsageExtension.java

@@ -175,11 +175,22 @@ implements CertAttrSet<String> {
      * Return the printable string.
      */
     public String toString() {
-        return(super.toString() +
+        StringBuilder sb = new StringBuilder();
-                "PrivateKeyUsage: [\n" +
+        sb.append(super.toString())
-                ((notBefore == null) ? "" : "From: " + notBefore.toString() + ", ")
+            .append("PrivateKeyUsage: [\n");
-                + ((notAfter == null) ? "" : "To: " + notAfter.toString())
+        if (notBefore != null) {
-                + "]\n");
+            sb.append("From: ")
+                .append(notBefore);
+            if (notAfter != null) {
+                sb.append(", ");
+            }
+        }
+        if (notAfter != null) {
+            sb.append("To: ")
+                .append(notAfter);
+        }
+        sb.append("]\n");
+        return sb.toString();
     }
 
     /**

jdk/src/java.base/share/classes/sun/security/x509/RDN.java

@@ -348,14 +348,11 @@ public class RDN {
             return assertion[0].toString();
         }
 
-        StringBuilder sb = new StringBuilder();
+        StringJoiner sj = new StringJoiner(" + ");
         for (int i = 0; i < assertion.length; i++) {
-            if (i != 0) {
+            sj.add(assertion[i].toString());
-                sb.append(" + ");
-            }
-            sb.append(assertion[i].toString());
         }
-        return sb.toString();
+        return sj.toString();
     }
 
     /*
@@ -376,14 +373,11 @@ public class RDN {
             return assertion[0].toRFC1779String(oidMap);
         }
 
-        StringBuilder sb = new StringBuilder();
+        StringJoiner sj = new StringJoiner(" + ");
         for (int i = 0; i < assertion.length; i++) {
-            if (i != 0) {
+            sj.add(assertion[i].toRFC1779String(oidMap));
-                sb.append(" + ");
-            }
-            sb.append(assertion[i].toRFC1779String(oidMap));
         }
-        return sb.toString();
+        return sj.toString();
     }
 
     /*

jdk/src/java.base/share/classes/sun/security/x509/SerialNumber.java

@@ -101,7 +101,7 @@ public class SerialNumber {
      * Return the SerialNumber as user readable string.
      */
     public String toString() {
-        return ("SerialNumber: [" + Debug.toHexString(serialNum) + "]");
+        return "SerialNumber: [" + Debug.toHexString(serialNum) + ']';
     }
 
     /**

jdk/src/java.base/share/classes/sun/security/x509/SubjectInfoAccessExtension.java

@@ -238,8 +238,8 @@ public class SubjectInfoAccessExtension extends Extension
      * Return the extension as user readable string.
      */
     public String toString() {
-        return super.toString() + "SubjectInfoAccess [\n  "
+        return super.toString() +
-               + accessDescriptions + "\n]\n";
+            "SubjectInfoAccess [\n  " + accessDescriptions + "\n]\n";
     }
 
 }

jdk/src/java.base/share/classes/sun/security/x509/SubjectKeyIdentifierExtension.java

@@ -115,8 +115,8 @@ implements CertAttrSet<String> {
      * Returns a printable representation.
      */
     public String toString() {
-        return super.toString() + "SubjectKeyIdentifier [\n"
+        return super.toString() +
-                + String.valueOf(id) + "]\n";
+            "SubjectKeyIdentifier [\n" + id + "]\n";
     }
 
     /**

jdk/src/java.base/share/classes/sun/security/x509/X500Name.java

@@ -31,6 +31,7 @@ import java.security.PrivilegedExceptionAction;
 import java.security.AccessController;
 import java.security.Principal;
 import java.util.*;
+import java.util.StringJoiner;
 
 import sun.security.util.*;
 import javax.security.auth.x500.X500Principal;
@@ -689,14 +690,11 @@ public class X500Name implements GeneralNameInterface, Principal {
          * The encodings of adjoining RelativeDistinguishedNames are separated
          * by a comma character (',' ASCII 44).
          */
-        StringBuilder fullname = new StringBuilder(48);
+        StringJoiner sj = new StringJoiner(",");
         for (int i = names.length - 1; i >= 0; i--) {
-            if (i < names.length - 1) {
+            sj.add(names[i].toRFC2253String(oidMap));
-                fullname.append(',');
-            }
-            fullname.append(names[i].toRFC2253String(oidMap));
         }
-        return fullname.toString();
+        return sj.toString();
     }
 
     public String getRFC2253CanonicalName() {
@@ -722,14 +720,11 @@ public class X500Name implements GeneralNameInterface, Principal {
          * The encodings of adjoining RelativeDistinguishedNames are separated
          * by a comma character (',' ASCII 44).
          */
-        StringBuilder fullname = new StringBuilder(48);
+        StringJoiner sj = new StringJoiner(",");
         for (int i = names.length - 1; i >= 0; i--) {
-            if (i < names.length - 1) {
+            sj.add(names[i].toRFC2253String(true));
-                fullname.append(',');
-            }
-            fullname.append(names[i].toRFC2253String(true));
         }
-        canonicalDn = fullname.toString();
+        canonicalDn = sj.toString();
         return canonicalDn;
     }
 
@@ -1064,16 +1059,16 @@ public class X500Name implements GeneralNameInterface, Principal {
             return;
         }
 
-        StringBuilder sb = new StringBuilder(48);
+        if (names == null) {
-        if (names != null) {
+            dn = "";
-            for (int i = names.length - 1; i >= 0; i--) {
+            return;
-                if (i != names.length - 1) {
-                    sb.append(", ");
-                }
-                sb.append(names[i].toString());
-            }
         }
-        dn = sb.toString();
+
+        StringJoiner sj = new StringJoiner(", ");
+        for (int i = names.length - 1; i >= 0; i--) {
+            sj.add(names[i].toString());
+        }
+        dn = sj.toString();
     }
 
     /*
@@ -1090,16 +1085,15 @@ public class X500Name implements GeneralNameInterface, Principal {
             return names[0].toRFC1779String(oidMap);
         }
 
-        StringBuilder sb = new StringBuilder(48);
+        if (names == null) {
-        if (names != null) {
+            return "";
-            for (int i = names.length - 1; i >= 0; i--) {
-                if (i != names.length - 1) {
-                    sb.append(", ");
-                }
-                sb.append(names[i].toRFC1779String(oidMap));
-            }
         }
-        return sb.toString();
+
+        StringJoiner sj = new StringJoiner(", ");
+        for (int i = names.length - 1; i >= 0; i--) {
+            sj.add(names[i].toRFC1779String(oidMap));
+        }
+        return sj.toString();
     }
 
     /****************************************************************/

jdk/src/java.base/share/classes/sun/security/x509/X509CRLEntryImpl.java

@@ -291,40 +291,47 @@ public class X509CRLEntryImpl extends X509CRLEntry
     public String toString() {
         StringBuilder sb = new StringBuilder();
 
-        sb.append(serialNumber.toString());
+        sb.append(serialNumber)
-        sb.append("  On: " + revocationDate.toString());
+            .append("  On: ")
+            .append(revocationDate);
         if (certIssuer != null) {
-            sb.append("\n    Certificate issuer: " + certIssuer);
+            sb.append("\n    Certificate issuer: ")
+                .append(certIssuer);
         }
         if (extensions != null) {
             Collection<Extension> allEntryExts = extensions.getAllExtensions();
             Extension[] exts = allEntryExts.toArray(new Extension[0]);
 
-            sb.append("\n    CRL Entry Extensions: " + exts.length);
+            sb.append("\n    CRL Entry Extensions: ")
+                .append(exts.length);
             for (int i = 0; i < exts.length; i++) {
-                sb.append("\n    [" + (i+1) + "]: ");
+                sb.append("\n    [")
+                    .append(i+1)
+                    .append("]: ");
                 Extension ext = exts[i];
                 try {
                     if (OIDMap.getClass(ext.getExtensionId()) == null) {
-                        sb.append(ext.toString());
+                        sb.append(ext);
                         byte[] extValue = ext.getExtensionValue();
                         if (extValue != null) {
                             DerOutputStream out = new DerOutputStream();
                             out.putOctetString(extValue);
                             extValue = out.toByteArray();
                             HexDumpEncoder enc = new HexDumpEncoder();
-                            sb.append("Extension unknown: "
+                            sb.append("Extension unknown: ")
-                                      + "DER encoded OCTET string =\n"
+                                .append("DER encoded OCTET string =\n")
-                                      + enc.encodeBuffer(extValue) + "\n");
+                                .append(enc.encodeBuffer(extValue))
+                                .append('\n');
                         }
-                    } else
+                    } else {
-                        sb.append(ext.toString()); //sub-class exists
+                        sb.append(ext); //sub-class exists
+                    }
                 } catch (Exception e) {
                     sb.append(", Error parsing this extension");
                 }
             }
         }
-        sb.append("\n");
+        sb.append('\n');
         return sb.toString();
     }
 

jdk/src/java.base/share/classes/sun/security/x509/X509CRLImpl.java

@@ -537,47 +537,65 @@ public class X509CRLImpl extends X509CRL implements DerEncoder {
      */
     public String toString() {
         StringBuilder sb = new StringBuilder();
-        sb.append("X.509 CRL v" + (version+1) + "\n");
+        sb.append("X.509 CRL v")
+            .append(version+1)
+            .append('\n');
         if (sigAlgId != null)
-            sb.append("Signature Algorithm: " + sigAlgId.toString() +
+            sb.append("Signature Algorithm: ")
-                  ", OID=" + (sigAlgId.getOID()).toString() + "\n");
+                .append(sigAlgId)
+                .append(", OID=")
+                .append(sigAlgId.getOID())
+                .append('\n');
         if (issuer != null)
-            sb.append("Issuer: " + issuer.toString() + "\n");
+            sb.append("Issuer: ")
+                .append(issuer)
+                .append('\n');
         if (thisUpdate != null)
-            sb.append("\nThis Update: " + thisUpdate.toString() + "\n");
+            sb.append("\nThis Update: ")
+                .append(thisUpdate)
+                .append('\n');
         if (nextUpdate != null)
-            sb.append("Next Update: " + nextUpdate.toString() + "\n");
+            sb.append("Next Update: ")
+                .append(nextUpdate)
+                .append('\n');
         if (revokedList.isEmpty())
             sb.append("\nNO certificates have been revoked\n");
         else {
-            sb.append("\nRevoked Certificates: " + revokedList.size());
+            sb.append("\nRevoked Certificates: ")
+                .append(revokedList.size());
             int i = 1;
             for (X509CRLEntry entry: revokedList) {
-                sb.append("\n[" + i++ + "] " + entry.toString());
+                sb.append("\n[")
+                    .append(i++)
+                    .append("] ")
+                    .append(entry);
             }
         }
         if (extensions != null) {
             Collection<Extension> allExts = extensions.getAllExtensions();
             Object[] objs = allExts.toArray();
-            sb.append("\nCRL Extensions: " + objs.length);
+            sb.append("\nCRL Extensions: ")
+                .append(objs.length);
             for (int i = 0; i < objs.length; i++) {
-                sb.append("\n[" + (i+1) + "]: ");
+                sb.append("\n[").append(i+1).append("]: ");
                 Extension ext = (Extension)objs[i];
                 try {
-                   if (OIDMap.getClass(ext.getExtensionId()) == null) {
+                    if (OIDMap.getClass(ext.getExtensionId()) == null) {
-                       sb.append(ext.toString());
+                        sb.append(ext);
-                       byte[] extValue = ext.getExtensionValue();
+                        byte[] extValue = ext.getExtensionValue();
-                       if (extValue != null) {
+                        if (extValue != null) {
-                           DerOutputStream out = new DerOutputStream();
+                            DerOutputStream out = new DerOutputStream();
-                           out.putOctetString(extValue);
+                            out.putOctetString(extValue);
-                           extValue = out.toByteArray();
+                            extValue = out.toByteArray();
-                           HexDumpEncoder enc = new HexDumpEncoder();
+                            HexDumpEncoder enc = new HexDumpEncoder();
-                           sb.append("Extension unknown: "
+                            sb.append("Extension unknown: ")
-                                     + "DER encoded OCTET string =\n"
+                                .append("DER encoded OCTET string =\n")
-                                     + enc.encodeBuffer(extValue) + "\n");
+                                .append(enc.encodeBuffer(extValue))
-                      }
+                                .append('\n');
-                   } else
+                        }
-                       sb.append(ext.toString()); // sub-class exists
+                    } else {
+                        sb.append(ext); // sub-class exists
+                    }
                 } catch (Exception e) {
                     sb.append(", Error parsing this extension");
                 }
@@ -585,10 +603,12 @@ public class X509CRLImpl extends X509CRL implements DerEncoder {
         }
         if (signature != null) {
             HexDumpEncoder encoder = new HexDumpEncoder();
-            sb.append("\nSignature:\n" + encoder.encodeBuffer(signature)
+            sb.append("\nSignature:\n")
-                      + "\n");
+                .append(encoder.encodeBuffer(signature))
-        } else
+                .append('\n');
+        } else {
             sb.append("NOT signed yet\n");
+        }
         return sb.toString();
     }
 

jdk/src/java.base/share/classes/sun/security/x509/X509CertImpl.java

@@ -81,7 +81,7 @@ public class X509CertImpl extends X509Certificate implements DerEncoder {
 
     private static final long serialVersionUID = -3457612960190864406L;
 
-    private static final String DOT = ".";
+    private static final char DOT = '.';
     /**
      * Public attribute names.
      */
@@ -799,17 +799,10 @@ public class X509CertImpl extends X509Certificate implements DerEncoder {
         if (info == null || algId == null || signature == null)
             return "";
 
-        StringBuilder sb = new StringBuilder();
-
-        sb.append("[\n");
-        sb.append(info.toString() + "\n");
-        sb.append("  Algorithm: [" + algId.toString() + "]\n");
-
         HexDumpEncoder encoder = new HexDumpEncoder();
-        sb.append("  Signature:\n" + encoder.encodeBuffer(signature));
+        return "[\n" + info + '\n' +
-        sb.append("\n]");
+            "  Algorithm: [" + algId + "]\n" +
-
+            "  Signature:\n" + encoder.encodeBuffer(signature) + "\n]";
-        return sb.toString();
     }
 
     // the strongly typed gets, as per java.security.cert.X509Certificate
@@ -1941,31 +1934,30 @@ public class X509CertImpl extends X509Certificate implements DerEncoder {
      * only contains 0-9 and A-F. No small case, no colon.
      */
     private String getCertificateFingerPrint(String mdAlg) {
-        String fingerPrint = "";
         try {
             byte[] encCertInfo = getEncoded();
             MessageDigest md = MessageDigest.getInstance(mdAlg);
             byte[] digest = md.digest(encCertInfo);
-            StringBuffer buf = new StringBuffer();
+            StringBuilder sb = new StringBuilder(digest.length * 2);
             for (int i = 0; i < digest.length; i++) {
-                byte2hex(digest[i], buf);
+                byte2hex(digest[i], sb);
             }
-            fingerPrint = buf.toString();
+            return sb.toString();
         } catch (NoSuchAlgorithmException | CertificateEncodingException e) {
             // ignored
         }
-        return fingerPrint;
+        return "";
     }
 
     /**
-     * Converts a byte to hex digit and writes to the supplied buffer
+     * Converts a byte to hex digit and writes to the supplied builder
      */
-    private static void byte2hex(byte b, StringBuffer buf) {
+    private static void byte2hex(byte b, StringBuilder buf) {
         char[] hexChars = { '0', '1', '2', '3', '4', '5', '6', '7', '8',
                 '9', 'A', 'B', 'C', 'D', 'E', 'F' };
         int high = ((b & 0xf0) >> 4);
         int low = (b & 0x0f);
-        buf.append(hexChars[high]);
+        buf.append(hexChars[high])
-        buf.append(hexChars[low]);
+            .append(hexChars[low]);
     }
 }

jdk/src/java.base/share/classes/sun/security/x509/X509CertInfo.java

@@ -299,55 +299,60 @@ public class X509CertInfo implements CertAttrSet<String> {
         }
         StringBuilder sb = new StringBuilder();
 
-        sb.append("[\n");
+        sb.append("[\n")
-        sb.append("  " + version.toString() + "\n");
+            .append("  ").append(version).append('\n')
-        sb.append("  Subject: " + subject.toString() + "\n");
+            .append("  Subject: ").append(subject).append('\n')
-        sb.append("  Signature Algorithm: " + algId.toString() + "\n");
+            .append("  Signature Algorithm: ").append(algId).append('\n')
-        sb.append("  Key:  " + pubKey.toString() + "\n");
+            .append("  Key:  ").append(pubKey).append('\n')
-        sb.append("  " + interval.toString() + "\n");
+            .append("  ").append(interval).append('\n')
-        sb.append("  Issuer: " + issuer.toString() + "\n");
+            .append("  Issuer: ").append(issuer).append('\n')
-        sb.append("  " + serialNum.toString() + "\n");
+            .append("  ").append(serialNum).append('\n');
 
         // optional v2, v3 extras
         if (issuerUniqueId != null) {
-            sb.append("  Issuer Id:\n" + issuerUniqueId.toString() + "\n");
+            sb.append("  Issuer Id:\n").append(issuerUniqueId).append('\n');
         }
         if (subjectUniqueId != null) {
-            sb.append("  Subject Id:\n" + subjectUniqueId.toString() + "\n");
+            sb.append("  Subject Id:\n").append(subjectUniqueId).append('\n');
         }
         if (extensions != null) {
             Collection<Extension> allExts = extensions.getAllExtensions();
             Extension[] exts = allExts.toArray(new Extension[0]);
-            sb.append("\nCertificate Extensions: " + exts.length);
+            sb.append("\nCertificate Extensions: ").append(exts.length);
             for (int i = 0; i < exts.length; i++) {
-                sb.append("\n[" + (i+1) + "]: ");
+                sb.append("\n[").append(i+1).append("]: ");
                 Extension ext = exts[i];
                 try {
                     if (OIDMap.getClass(ext.getExtensionId()) == null) {
-                        sb.append(ext.toString());
+                        sb.append(ext);
                         byte[] extValue = ext.getExtensionValue();
                         if (extValue != null) {
                             DerOutputStream out = new DerOutputStream();
                             out.putOctetString(extValue);
                             extValue = out.toByteArray();
                             HexDumpEncoder enc = new HexDumpEncoder();
-                            sb.append("Extension unknown: "
+                            sb.append("Extension unknown: ")
-                                      + "DER encoded OCTET string =\n"
+                                .append("DER encoded OCTET string =\n")
-                                      + enc.encodeBuffer(extValue) + "\n");
+                                .append(enc.encodeBuffer(extValue))
+                                .append('\n');
                         }
-                    } else
+                    } else {
-                        sb.append(ext.toString()); //sub-class exists
+                        sb.append(ext); //sub-class exists
+                    }
                 } catch (Exception e) {
                     sb.append(", Error parsing this extension");
                 }
             }
             Map<String,Extension> invalid = extensions.getUnparseableExtensions();
             if (invalid.isEmpty() == false) {
-                sb.append("\nUnparseable certificate extensions: " + invalid.size());
+                sb.append("\nUnparseable certificate extensions: ")
+                    .append(invalid.size());
                 int i = 1;
                 for (Extension ext : invalid.values()) {
-                    sb.append("\n[" + (i++) + "]: ");
+                    sb.append("\n[")
-                    sb.append(ext);
+                        .append(i++)
+                        .append("]: ")
+                        .append(ext);
                 }
             }
         }