8315678: Classfile API ConstantPool::entryCount and ConstantPool::entryByIndex methods are confusing

Reviewed-by: briangoetz

src/java.base/share/classes/jdk/internal/classfile/constantpool/ClassEntry.java

@@ -31,6 +31,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_Class_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.1 The CONSTANT_Class_info Structure
  */
 public sealed interface ClassEntry
         extends LoadableConstantEntry

src/java.base/share/classes/jdk/internal/classfile/constantpool/ConstantDynamicEntry.java

@@ -34,6 +34,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_Dynamic_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.10 The CONSTANT_Dynamic_info and CONSTANT_InvokeDynamic_info Structures
  */
 public sealed interface ConstantDynamicEntry
         extends DynamicConstantPoolEntry, LoadableConstantEntry

src/java.base/share/classes/jdk/internal/classfile/constantpool/ConstantPool.java

@@ -25,27 +25,56 @@
 
 package jdk.internal.classfile.constantpool;
 
+import java.util.Iterator;
+import java.util.NoSuchElementException;
 import jdk.internal.classfile.BootstrapMethodEntry;
 import jdk.internal.classfile.ClassReader;
 
 /**
  * Provides read access to the constant pool and bootstrap method table of a
  * classfile.
+ * @jvms 4.4 The Constant Pool
  */
-public sealed interface ConstantPool
+public sealed interface ConstantPool extends Iterable<PoolEntry>
         permits ClassReader, ConstantPoolBuilder {
 
     /**
      * {@return the entry at the specified index}
      *
      * @param index the index within the pool of the desired entry
+     * @throws ConstantPoolException if the index is out of range of the
+     *         constant pool, or is considered unusable
      */
     PoolEntry entryByIndex(int index);
 
     /**
-     * {@return the number of entries in the constant pool}
+     * {@return the size of the constant pool}
      */
-    int entryCount();
+    int size();
+
+    /**
+     * @{return an iterator over pool entries}
+     */
+    @Override
+    default Iterator<PoolEntry> iterator() {
+        return new Iterator<>() {
+            int index = 1;
+
+            @Override
+            public boolean hasNext() {
+                return index < size();
+            }
+
+            @Override
+            public PoolEntry next() {
+                if (!hasNext()) throw new NoSuchElementException();
+                var e = entryByIndex(index);
+                index += e.width();
+                return e;
+            }
+        };
+    }
+
 
     /**
      * {@return the {@link BootstrapMethodEntry} at the specified index within
@@ -53,6 +82,8 @@ public sealed interface ConstantPool
      *
      * @param index the index within the bootstrap method table of the desired
      *              entry
+     * @throws ConstantPoolException if the index is out of range of the
+     *         bootstrap methods
      */
     BootstrapMethodEntry bootstrapMethodEntry(int index);
 

src/java.base/share/classes/jdk/internal/classfile/constantpool/DoubleEntry.java

@@ -30,6 +30,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_Double_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.5 The CONSTANT_Long_info and CONSTANT_Double_info Structures
  */
 public sealed interface DoubleEntry
         extends AnnotationConstantValueEntry, ConstantValueEntry

src/java.base/share/classes/jdk/internal/classfile/constantpool/FieldRefEntry.java

@@ -29,6 +29,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_Fieldref_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.2 The CONSTANT_Fieldref_info, CONSTANT_Methodref_info, and CONSTANT_InterfaceMethodref_info Structures
  */
 public sealed interface FieldRefEntry extends MemberRefEntry
         permits AbstractPoolEntry.FieldRefEntryImpl {

src/java.base/share/classes/jdk/internal/classfile/constantpool/FloatEntry.java

@@ -30,6 +30,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_Float_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.4 The CONSTANT_Integer_info and CONSTANT_Float_info Structures
  */
 public sealed interface FloatEntry
         extends AnnotationConstantValueEntry, ConstantValueEntry

src/java.base/share/classes/jdk/internal/classfile/constantpool/IntegerEntry.java

@@ -30,6 +30,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_Integer_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.4 The CONSTANT_Integer_info and CONSTANT_Float_info Structures
  */
 public sealed interface IntegerEntry
         extends AnnotationConstantValueEntry, ConstantValueEntry

src/java.base/share/classes/jdk/internal/classfile/constantpool/InterfaceMethodRefEntry.java

@@ -29,6 +29,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_InterfaceMethodRef_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.2 The CONSTANT_Fieldref_info, CONSTANT_Methodref_info, and CONSTANT_InterfaceMethodref_info Structures
  */
 public sealed interface InterfaceMethodRefEntry
         extends MemberRefEntry

src/java.base/share/classes/jdk/internal/classfile/constantpool/InvokeDynamicEntry.java

@@ -32,6 +32,7 @@ import jdk.internal.classfile.impl.Util;
 
 /**
  * Models a constant pool entry for a dynamic call site.
+ * @jvms 4.4.10 The CONSTANT_Dynamic_info and CONSTANT_InvokeDynamic_info Structures
  */
 public sealed interface InvokeDynamicEntry
         extends DynamicConstantPoolEntry

src/java.base/share/classes/jdk/internal/classfile/constantpool/LongEntry.java

@@ -30,6 +30,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_Long_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.5 The CONSTANT_Long_info and CONSTANT_Double_info Structures
  */
 public sealed interface LongEntry
         extends AnnotationConstantValueEntry, ConstantValueEntry

src/java.base/share/classes/jdk/internal/classfile/constantpool/MethodHandleEntry.java

@@ -32,6 +32,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_MethodHandle_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.8 The CONSTANT_MethodHandle_info Structure
  */
 public sealed interface MethodHandleEntry
         extends LoadableConstantEntry

src/java.base/share/classes/jdk/internal/classfile/constantpool/MethodRefEntry.java

@@ -29,6 +29,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_MethodRef_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.2 The CONSTANT_Fieldref_info, CONSTANT_Methodref_info, and CONSTANT_InterfaceMethodref_info Structures
  */
 public sealed interface MethodRefEntry extends MemberRefEntry
         permits AbstractPoolEntry.MethodRefEntryImpl {

src/java.base/share/classes/jdk/internal/classfile/constantpool/MethodTypeEntry.java

@@ -32,6 +32,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_MethodType_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.9 The CONSTANT_MethodType_info Structure
  */
 public sealed interface MethodTypeEntry
         extends LoadableConstantEntry

src/java.base/share/classes/jdk/internal/classfile/constantpool/ModuleEntry.java

@@ -30,6 +30,7 @@ import java.lang.constant.ModuleDesc;
 /**
  * Models a {@code CONSTANT_Module_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.11 The CONSTANT_Module_info Structure
  */
 public sealed interface ModuleEntry extends PoolEntry
         permits AbstractPoolEntry.ModuleEntryImpl {

src/java.base/share/classes/jdk/internal/classfile/constantpool/NameAndTypeEntry.java

@@ -29,6 +29,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_NameAndType_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.6 The CONSTANT_NameAndType_info Structure
  */
 public sealed interface NameAndTypeEntry extends PoolEntry
         permits AbstractPoolEntry.NameAndTypeEntryImpl {

src/java.base/share/classes/jdk/internal/classfile/constantpool/PackageEntry.java

@@ -30,6 +30,7 @@ import java.lang.constant.PackageDesc;
 /**
  * Models a {@code CONSTANT_Package_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.12 The CONSTANT_Package_info Structure
  */
 public sealed interface PackageEntry extends PoolEntry
         permits AbstractPoolEntry.PackageEntryImpl {

src/java.base/share/classes/jdk/internal/classfile/constantpool/StringEntry.java

@@ -29,6 +29,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_String_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.3 The CONSTANT_String_info Structure
  */
 public sealed interface StringEntry
         extends ConstantValueEntry

src/java.base/share/classes/jdk/internal/classfile/constantpool/Utf8Entry.java

@@ -29,6 +29,7 @@ import jdk.internal.classfile.impl.AbstractPoolEntry;
 /**
  * Models a {@code CONSTANT_UTF8_info} constant in the constant pool of a
  * classfile.
+ * @jvms 4.4.7 The CONSTANT_Utf8_info Structure
  */
 public sealed interface Utf8Entry
         extends CharSequence, AnnotationConstantValueEntry

src/java.base/share/classes/jdk/internal/classfile/impl/ClassPrinterImpl.java

@@ -570,9 +570,8 @@ public final class ClassPrinterImpl {
     private static Node[] constantPoolToTree(ConstantPool cp, Verbosity verbosity) {
         if (verbosity == Verbosity.TRACE_ALL) {
             var cpNode = new MapNodeImpl(BLOCK, "constant pool");
-            for (int i = 1; i < cp.entryCount();) {
-                var e = cp.entryByIndex(i);
-                cpNode.with(new MapNodeImpl(FLOW, i)
+            for (PoolEntry e : cp) {
+                cpNode.with(new MapNodeImpl(FLOW, e.index())
                         .with(leaf("tag", switch (e.tag()) {
                             case TAG_UTF8 -> "Utf8";
                             case TAG_INTEGER -> "Integer";
@@ -637,7 +636,6 @@ public final class ClassPrinterImpl {
                                 "value", String.valueOf(ve.constantValue())
                             );
                         }));
-                i += e.width();
             }
             return new Node[]{cpNode};
         } else {

src/java.base/share/classes/jdk/internal/classfile/impl/ClassReaderImpl.java

@@ -144,7 +144,7 @@ public final class ClassReaderImpl
     }
 
     @Override
-    public int entryCount() {
+    public int size() {
         return constantPoolCount;
     }
 
@@ -189,6 +189,9 @@ public final class ClassReaderImpl
 
     @Override
     public BootstrapMethodEntryImpl bootstrapMethodEntry(int index) {
+        if (index < 0 || index >= bootstrapMethodCount()) {
+            throw new ConstantPoolException("Bad BSM index: " + index);
+        }
         return bsmEntries().get(index);
     }
 
@@ -312,6 +315,9 @@ public final class ClassReaderImpl
         PoolEntry info = cp[index];
         if (info == null) {
             int offset = cpOffset[index];
+            if (offset == 0) {
+                throw new ConstantPoolException("Unusable CP index: " + index);
+            }
             int tag = readU1(offset);
             final int q = offset + 1;
             info = switch (tag) {

src/java.base/share/classes/jdk/internal/classfile/impl/SplitConstantPool.java

@@ -28,6 +28,7 @@ import java.lang.constant.ConstantDesc;
 import java.lang.constant.MethodTypeDesc;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Objects;
 
 import jdk.internal.classfile.Attribute;
 import jdk.internal.classfile.Attributes;
@@ -75,6 +76,7 @@ import static jdk.internal.classfile.Classfile.TAG_MODULE;
 import static jdk.internal.classfile.Classfile.TAG_NAMEANDTYPE;
 import static jdk.internal.classfile.Classfile.TAG_PACKAGE;
 import static jdk.internal.classfile.Classfile.TAG_STRING;
+import jdk.internal.classfile.constantpool.ConstantPoolException;
 
 public final class SplitConstantPool implements ConstantPoolBuilder {
 
@@ -101,7 +103,7 @@ public final class SplitConstantPool implements ConstantPoolBuilder {
 
     public SplitConstantPool(ClassReader parent) {
         this.parent = (ClassReaderImpl) parent;
-        this.parentSize = parent.entryCount();
+        this.parentSize = parent.size();
         this.parentBsmSize = parent.bootstrapMethodCount();
         this.size = parentSize;
         this.bsmSize = parentBsmSize;
@@ -110,7 +112,7 @@ public final class SplitConstantPool implements ConstantPoolBuilder {
     }
 
     @Override
-    public int entryCount() {
+    public int size() {
         return size;
     }
 
@@ -121,13 +123,23 @@ public final class SplitConstantPool implements ConstantPoolBuilder {
 
     @Override
     public PoolEntry entryByIndex(int index) {
-        return (index < parentSize)
+        if (index <= 0 || index >= size()) {
+            throw new ConstantPoolException("Bad CP index: " + index);
+        }
+        PoolEntry pe = (index < parentSize)
                ? parent.entryByIndex(index)
                : myEntries[index - parentSize];
+        if (pe == null) {
+            throw new ConstantPoolException("Unusable CP index: " + index);
+        }
+        return pe;
     }
 
     @Override
     public BootstrapMethodEntryImpl bootstrapMethodEntry(int index) {
+        if (index < 0 || index >= bootstrapMethodCount()) {
+            throw new ConstantPoolException("Bad BSM index: " + index);
+        }
         return (index < parentBsmSize)
                ? parent.bootstrapMethodEntry(index)
                : myBsmEntries[index - parentBsmSize];
@@ -170,15 +182,15 @@ public final class SplitConstantPool implements ConstantPoolBuilder {
     @Override
     public void writeTo(BufWriter buf) {
         int writeFrom = 1;
-        if (entryCount() >= 65536) {
-            throw new IllegalArgumentException(String.format("Constant pool is too large %d", entryCount()));
+        if (size() >= 65536) {
+            throw new IllegalArgumentException(String.format("Constant pool is too large %d", size()));
         }
-        buf.writeU2(entryCount());
+        buf.writeU2(size());
         if (parent != null && buf.constantPool().canWriteDirect(this)) {
             parent.writeConstantPoolEntries(buf);
-            writeFrom = parent.entryCount();
+            writeFrom = parent.size();
         }
-        for (int i = writeFrom; i < entryCount(); ) {
+        for (int i = writeFrom; i < size(); ) {
             PoolEntry info = entryByIndex(i);
             info.writeTo(buf);
             i += info.width();

src/java.base/share/classes/jdk/internal/classfile/impl/TemporaryConstantPool.java

@@ -166,7 +166,7 @@ public final class TemporaryConstantPool implements ConstantPoolBuilder {
     }
 
     @Override
-    public int entryCount() {
+    public int size() {
         throw new UnsupportedOperationException();
     }
 

src/java.base/share/classes/jdk/internal/classfile/impl/verifier/VerificationWrapper.java

@@ -162,7 +162,7 @@ public final class VerificationWrapper {
         }
 
         int entryCount() {
-            return cp.entryCount();
+            return cp.size();
         }
 
         String classNameAt(int index) {

src/jdk.jlink/share/classes/jdk/tools/jlink/internal/plugins/StringSharingPlugin.java

@@ -175,9 +175,8 @@ public class StringSharingPlugin extends AbstractPlugin implements ResourcePrevi
 
             private void scanConstantPool(Set<Integer> utf8Descriptors)
                     throws Exception {
-                for (int i = 1; i < cm.constantPool().entryCount(); i += cm.constantPool().entryByIndex(i).width()) {
-                    try {
-                        PoolEntry info = cm.constantPool().entryByIndex(i);
+                try {
+                    for (PoolEntry info : cm.constantPool()) {
                         switch (info) {
                             case NameAndTypeEntry nameAndType ->
                                 utf8Descriptors.add(nameAndType.type().index());
@@ -185,9 +184,9 @@ public class StringSharingPlugin extends AbstractPlugin implements ResourcePrevi
                                 utf8Descriptors.add(mt.descriptor().index());
                             default -> {}
                         }
-                    } catch (ConstantPoolException ex) {
-                        throw new IOException(ex);
                     }
+                } catch (ConstantPoolException ex) {
+                    throw new IOException(ex);
                 }
             }
         }

test/jdk/jdk/classfile/ConstantPoolCopyTest.java

@@ -102,9 +102,9 @@ class ConstantPoolCopyTest {
         ConstantPool cp = c.constantPool();
         ConstantPoolBuilder cp2 = new SplitConstantPool((ClassReader) cp);
 
-        assertEquals(cp2.entryCount(), cp.entryCount(), "Cloned constant pool must be same size");
+        assertEquals(cp2.size(), cp.size(), "Cloned constant pool must be same size");
 
-        for (int i = 1; i < cp.entryCount();) {
+        for (int i = 1; i < cp.size();) {
             PoolEntry cp1i = cp.entryByIndex(i);
             PoolEntry cp2i = cp2.entryByIndex(i);
             assertTrue(representsTheSame(cp1i, cp2i), cp2i + " does not represent the same constant pool entry as " + cp1i);

test/jdk/jdk/classfile/CorpusTest.java

@@ -248,13 +248,13 @@ class CorpusTest {
         var cp1 = cc.parse(orig).constantPool();
         var cp2 = cc.parse(transformed).constantPool();
 
-        for (int i = 1; i < cp1.entryCount(); i += cp1.entryByIndex(i).width()) {
+        for (int i = 1; i < cp1.size(); i += cp1.entryByIndex(i).width()) {
             assertEquals(cpiToString(cp1.entryByIndex(i)), cpiToString(cp2.entryByIndex(i)));
         }
 
-        if (cp1.entryCount() != cp2.entryCount()) {
-            StringBuilder failMsg = new StringBuilder("Extra entries in constant pool (" + (cp2.entryCount() - cp1.entryCount()) + "): ");
-            for (int i = cp1.entryCount(); i < cp2.entryCount(); i += cp2.entryByIndex(i).width())
+        if (cp1.size() != cp2.size()) {
+            StringBuilder failMsg = new StringBuilder("Extra entries in constant pool (" + (cp2.size() - cp1.size()) + "): ");
+            for (int i = cp1.size(); i < cp2.size(); i += cp2.entryByIndex(i).width())
                 failMsg.append("\n").append(cp2.entryByIndex(i));
             fail(failMsg.toString());
         }
@@ -272,7 +272,7 @@ class CorpusTest {
         var cf = Classfile.of().parse(bytes);
         var pool = cf.constantPool();
         Set<String> entryStrings = new HashSet<>();
-        for (int i = 1; i < pool.entryCount(); i += pool.entryByIndex(i).width()) {
+        for (int i = 1; i < pool.size(); i += pool.entryByIndex(i).width()) {
             String s = cpiToString(pool.entryByIndex(i));
             if (entryStrings.contains(s)) {
                 for (int j=1; j<i; j += pool.entryByIndex(j).width()) {

test/jdk/jdk/classfile/Utf8EntryTest.java

@@ -185,8 +185,7 @@ class Utf8EntryTest {
     }
 
     static StringEntry obtainStringEntry(ConstantPool cp) {
-        for (int i = 1; i < cp.entryCount(); i++) {
-            PoolEntry entry = cp.entryByIndex(i);
+        for (PoolEntry entry : cp) {
             if (entry instanceof StringEntry se) {
                 return se;
             }

test/langtools/tools/javac/7153958/CPoolRefClassContainingInlinedCts.java

@@ -75,14 +75,10 @@ public class CPoolRefClassContainingInlinedCts {
         File file = new File(testClasses,
                 CPoolRefClassContainingInlinedCts.class.getName() + ".class");
         ClassModel classFile = Classfile.of().parse(file.toPath());
-        int i = 1;
-        PoolEntry cpInfo;
-        while (i < classFile.constantPool().entryCount()) {
-            cpInfo = classFile.constantPool().entryByIndex(i);
+        for (PoolEntry cpInfo : classFile.constantPool()) {
             if (cpInfo instanceof ClassEntry classEntry) {
                 checkClassName(classEntry.asInternalName());
             }
-            i += cpInfo.width();
         }
         if (numberOfReferencedClassesToBeChecked != 16) {
             throw new AssertionError("Class reference missing in the constant pool");

test/langtools/tools/javac/8000518/DuplicateConstantPoolEntry.java

@@ -47,6 +47,7 @@ import javax.tools.JavaCompiler;
 import javax.tools.JavaFileObject;
 import javax.tools.SimpleJavaFileObject;
 import javax.tools.ToolProvider;
+import jdk.internal.classfile.constantpool.PoolEntry;
 
 /*
  * This bug was reproduced having two classes B and C referenced from a class A
@@ -96,17 +97,12 @@ public class DuplicateConstantPoolEntry {
         File file = new File("A.class");
         ClassModel classFile = Classfile.of().parse(file.toPath());
         ConstantPool constantPool = classFile.constantPool();
-        for (int i = 1;
-                i < constantPool.entryCount() - 1;
-                i += constantPool.entryByIndex(i).width()) {
-            for (int j = i + constantPool.entryByIndex(i).width();
-                    j < constantPool.entryCount();
-                    j += constantPool.entryByIndex(j).width()) {
-                if (constantPool.entryByIndex(i).toString().
-                        equals(constantPool.entryByIndex(j).toString())) {
+        for (PoolEntry pe1 : constantPool) {
+            for (PoolEntry pe2 : constantPool) {
+                if (pe2.index() > pe1.index() && pe1.equals(pe2)) {
                     throw new AssertionError(
                             "Duplicate entries in the constant pool at positions " +
-                            i + " and " + j);
+                            pe1.index() + " and " + pe2.index());
                 }
             }
         }

test/langtools/tools/javac/NoStringToLower.java

@@ -109,9 +109,8 @@ public class NoStringToLower {
     void scan(JavaFileObject fo) throws IOException {
         try (InputStream in = fo.openInputStream()) {
             ClassModel cf = Classfile.of().parse(in.readAllBytes());
-            ConstantPool cp = cf.constantPool();
-            for (int i = 1; i < cp.entryCount(); i += cp.entryByIndex(i).width()) {
-                if (cp.entryByIndex(i) instanceof MethodRefEntry ref) {
+            for (PoolEntry pe : cf.constantPool()) {
+                if (pe instanceof MethodRefEntry ref) {
                     String methodDesc = ref.owner().name().stringValue() + "." + ref.name().stringValue() + ":" + ref.type().stringValue();
 
                     if ("java/lang/String.toLowerCase:()Ljava/lang/String;".equals(methodDesc)) {

test/langtools/tools/javac/T8011181/EmptyUTF8ForInnerClassNameTest.java

@@ -58,8 +58,7 @@ public class EmptyUTF8ForInnerClassNameTest {
     void checkClassFile(final Path path) throws Exception {
         ClassModel classFile = Classfile.of().parse(
                 new BufferedInputStream(Files.newInputStream(path)).readAllBytes());
-        for (int i = 1; i < classFile.constantPool().entryCount(); ++i) {
-            PoolEntry pe = classFile.constantPool().entryByIndex(i);
+        for (PoolEntry pe : classFile.constantPool()) {
             if (pe instanceof Utf8Entry utf8Info) {
                 Assert.check(utf8Info.stringValue().length() > 0,
                         "UTF8 with length 0 found at class " + classFile.thisClass().name());

test/langtools/tools/javac/classfiles/T8255757/T8255757.java

@@ -80,10 +80,9 @@ public class T8255757 extends TestRunner {
                 .run();
 
         ClassModel cf = Classfile.of().parse(curPath.resolve("Test.class"));
-        ConstantPool cp = cf.constantPool();
         int num = 0;
-        for (int i = 1; i < cp.entryCount(); i += cp.entryByIndex(i).width()) {
-            if (cp.entryByIndex(i) instanceof MethodRefEntry methodRefEntry) {
+        for (PoolEntry pe : cf.constantPool()) {
+            if (pe instanceof MethodRefEntry methodRefEntry) {
                 String class_name = methodRefEntry.owner().asInternalName();
                 String method_name = methodRefEntry.name().stringValue();
                 String method_type = methodRefEntry.type().stringValue();

test/langtools/tools/javac/classfiles/attributes/innerclasses/InnerClassesHierarchyTest.java

@@ -63,8 +63,8 @@ public class InnerClassesHierarchyTest extends TestResult {
         for (File file : Arrays.asList(classDir.listFiles(filter))) {
             ClassModel classFile = readClassFile(file);
             String className = classFile.thisClass().name().stringValue();
-            for (int i = 1; i < classFile.constantPool().entryCount(); ++i) {
-                if (classFile.constantPool().entryByIndex(i) instanceof ClassEntry classInfo
+            for (PoolEntry pe : classFile.constantPool()) {
+                if (pe instanceof ClassEntry classInfo
                         && classInfo.asSymbol().isClassOrInterface()) {
                     String cpClassName = classInfo.asInternalName();
                     if (isInnerClass(cpClassName)) {

test/langtools/tools/javac/diags/CheckResourceKeys.java

@@ -497,8 +497,8 @@ public class CheckResourceKeys {
     void scan(JavaFileObject fo, Set<String> results) throws IOException {
         try (InputStream in = fo.openInputStream()) {
             ClassModel cm = Classfile.of().parse(in.readAllBytes());
-            for (int i = 1; i < cm.constantPool().entryCount(); ++i) {
-                if (cm.constantPool().entryByIndex(i) instanceof Utf8Entry entry) {
+            for (PoolEntry pe : cm.constantPool()) {
+                if (pe instanceof Utf8Entry entry) {
                     String v = entry.stringValue();
                     if (v.matches("[A-Za-z0-9-_.]+"))
                         results.add(v);

test/langtools/tools/javac/jvm/ClassRefDupInConstantPoolTest.java

@@ -47,8 +47,8 @@ public class ClassRefDupInConstantPoolTest {
 
         int duplicates = 0;
         TreeSet<String> set = new TreeSet<>();
-        for (int i = 1; i < pool.entryCount(); i += pool.entryByIndex(i).width()) {
-            if (pool.entryByIndex(i) instanceof ClassEntry ce) {
+        for (PoolEntry pe : pool) {
+            if (pe instanceof ClassEntry ce) {
                 if (!set.add(ce.asInternalName())) {
                     duplicates++;
                     System.out.println("DUPLICATE CLASS REF " + ce.asInternalName());

test/langtools/tools/javac/lambda/ByteCodeTest.java

@@ -83,7 +83,7 @@ public class ByteCodeTest {
             e.printStackTrace();
         }
         assert c != null;
-        ConstantPoolVisitor cpv = new ConstantPoolVisitor(c, c.constantPool().entryCount());
+        ConstantPoolVisitor cpv = new ConstantPoolVisitor(c, c.constantPool().size());
         Map<Integer, String> hm = cpv.getBSMMap();
 
         List<String> expectedValList = tc.getExpectedArgValues();

test/langtools/tools/javac/patterns/MatchExceptionTest.java

@@ -44,6 +44,7 @@ import jdk.internal.classfile.*;
 import jdk.internal.classfile.constantpool.ClassEntry;
 import jdk.internal.classfile.constantpool.ConstantPool;
 import java.util.Arrays;
+import jdk.internal.classfile.constantpool.PoolEntry;
 
 import toolbox.JavacTask;
 import toolbox.TestRunner;
@@ -118,9 +119,8 @@ public class MatchExceptionTest extends TestRunner {
                 cf = Classfile.of().parse(curPath.resolve("Test.class"));
                 boolean incompatibleClassChangeErrror = false;
                 boolean matchException = false;
-                ConstantPool cp = cf.constantPool();
-                for (int i = 1; i < cp.entryCount(); i += cp.entryByIndex(i).width()) {
-                    if (cp.entryByIndex(i) instanceof ClassEntry clazz) {
+                for (PoolEntry pe : cf.constantPool()) {
+                    if (pe instanceof ClassEntry clazz) {
                         incompatibleClassChangeErrror |= clazz.name().equalsString(
                                 "java/lang/IncompatibleClassChangeError");
                         matchException |= clazz.name().equalsString("java/lang/MatchException");

test/langtools/tools/javac/records/RecordCompilationTests.java

@@ -1276,8 +1276,8 @@ public class RecordCompilationTests extends CompilationTestCase {
             for (final File fileEntry : Objects.requireNonNull(dir.listFiles())) {
                 if (fileEntry.getName().endsWith("R.class")) {
                     ClassModel classFile = Classfile.of().parse(fileEntry.toPath());
-                    for (int i = 1; i < classFile.constantPool().entryCount(); ++i) {
-                        if (classFile.constantPool().entryByIndex(i) instanceof FieldRefEntry fieldRefEntry) {
+                    for (PoolEntry pe : classFile.constantPool()) {
+                        if (pe instanceof FieldRefEntry fieldRefEntry) {
                             numberOfFieldRefs++;
                             NameAndTypeEntry nameAndType = (NameAndTypeEntry) classFile.constantPool()
                                             .entryByIndex(fieldRefEntry.nameAndType().index());

test/langtools/tools/javac/resolve/NoObjectToString.java

@@ -49,8 +49,7 @@ public class NoObjectToString {
         try (InputStream in = NoObjectToString.class.getResourceAsStream("NoObjectToString$Test.class")) {
             assert in != null;
             ClassModel cm = Classfile.of().parse(in.readAllBytes());
-            for (int i = 1; i < cm.constantPool().entryCount(); ++i) {
-                PoolEntry pe = cm.constantPool().entryByIndex(i);
+            for (PoolEntry pe : cm.constantPool()) {
                 if (pe instanceof MethodRefEntry ref) {
                     String methodDesc = ref.owner().name() + "." + ref.nameAndType().name() + ":" + ref.nameAndType().type();
 

test/langtools/tools/javap/classfile/T6887895.java

@@ -49,8 +49,8 @@ public class T6887895 {
 
         ClassModel cm = getClassFile("T6887895$Test.class");
         ConstantPool cp = cm.constantPool();
-        for (int i = 1; i < cp.entryCount(); ++i) {
-            if (cp.entryByIndex(i) instanceof ClassEntry ce) {
+        for (PoolEntry pe : cp) {
+            if (pe instanceof ClassEntry ce) {
                 String name = ce.asInternalName();
                 System.out.println("found: " + name);
                 if (ce.asSymbol().isClassOrInterface())