http://fastutil.di.unimi.it/: fastutil extends the Java Collections Framework by providing type-specific maps, sets, lists and priority queues with a small memory footprint and fast access and insertion; provides also big (64-bit) arrays, sets and lists, and fast, practical I/O classes for binary and text files.
  • Sebastiano Vigna 
final class it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$KeyIterator extends it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap<V>.MapIterator implements it.unimi.dsi.fastutil.bytes.ByteIterator
  minor version: 0
  major version: 59
  flags: flags: (0x0030) ACC_FINAL, ACC_SUPER
  this_class: it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$KeyIterator
  super_class: it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$MapIterator
{
  final it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap this$0;
    descriptor: Lit/unimi/dsi/fastutil/bytes/Byte2ReferenceOpenHashMap;
    flags: (0x1010) ACC_FINAL, ACC_SYNTHETIC

  public void <init>(it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap);
    descriptor: (Lit/unimi/dsi/fastutil/bytes/Byte2ReferenceOpenHashMap;)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=2, args_size=2
        start local 0 // it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$KeyIterator this
         0: .line 885
            aload 0 /* this */
            aload 1
            putfield it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$KeyIterator.this$0:Lit/unimi/dsi/fastutil/bytes/Byte2ReferenceOpenHashMap;
         1: .line 886
            aload 0 /* this */
            aload 1
            invokespecial it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$MapIterator.<init>:(Lit/unimi/dsi/fastutil/bytes/Byte2ReferenceOpenHashMap;)V
         2: .line 887
            return
        end local 0 // it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$KeyIterator this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    3     0  this  Lit/unimi/dsi/fastutil/bytes/Byte2ReferenceOpenHashMap$KeyIterator;
    MethodParameters:
        Name  Flags
      this$0  final

  public byte nextByte();
    descriptor: ()B
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=1, args_size=1
        start local 0 // it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$KeyIterator this
         0: .line 890
            aload 0 /* this */
            getfield it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$KeyIterator.this$0:Lit/unimi/dsi/fastutil/bytes/Byte2ReferenceOpenHashMap;
            getfield it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap.key:[B
            aload 0 /* this */
            invokevirtual it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$KeyIterator.nextEntry:()I
            baload
            ireturn
        end local 0 // it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$KeyIterator this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lit/unimi/dsi/fastutil/bytes/Byte2ReferenceOpenHashMap$KeyIterator;

  public java.lang.Object next();
    descriptor: ()Ljava/lang/Object;
    flags: (0x1041) ACC_PUBLIC, ACC_BRIDGE, ACC_SYNTHETIC
    Code:
      stack=1, locals=1, args_size=1
         0: .line 1
            aload 0
            invokeinterface it.unimi.dsi.fastutil.bytes.ByteIterator.next:()Ljava/lang/Byte;
            areturn
      LocalVariableTable:
        Start  End  Slot  Name  Signature
}
Signature: Lit/unimi/dsi/fastutil/bytes/Byte2ReferenceOpenHashMap<TV;>.MapIterator;Lit/unimi/dsi/fastutil/bytes/ByteIterator;
SourceFile: "Byte2ReferenceOpenHashMap.java"
NestHost: it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap
InnerClasses:
  private final KeyIterator = it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$KeyIterator of it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap
  private MapIterator = it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap$MapIterator of it.unimi.dsi.fastutil.bytes.Byte2ReferenceOpenHashMap