https://github.com/eclipse/eclipse-collections/eclipse-collections: Eclipse Collections is a collections framework for Java. It has JDK-compatible List, Set and Map implementations with a rich API and set of utility classes that work with any JDK compatible Collections, Arrays, Maps or Strings. The iteration protocol was inspired by the Smalltalk collection framework.
  • Craig P. Motlin
  • Donald Raab
  • Mohammad A. Rezaei
  • Hiroshi Ito
  • Nikhil J. Nanivadekar 
class org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1 implements org.eclipse.collections.api.block.procedure.primitive.DoubleProcedure
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1
  super_class: java.lang.Object
{
  private int index;
    descriptor: I
    flags: (0x0002) ACC_PRIVATE

  final org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet this$1;
    descriptor: Lorg/eclipse/collections/impl/map/mutable/primitive/DoubleObjectHashMap$KeySet;
    flags: (0x1010) ACC_FINAL, ACC_SYNTHETIC

  private final double[] val$result;
    descriptor: [D
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  void <init>(org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet, double[]);
    descriptor: (Lorg/eclipse/collections/impl/map/mutable/primitive/DoubleObjectHashMap$KeySet;[D)V
    flags: (0x0000) 
    Code:
      stack=2, locals=3, args_size=3
        start local 0 // org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1 this
         0: .line 3730
            aload 0 /* this */
            aload 1
            putfield org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1.this$1:Lorg/eclipse/collections/impl/map/mutable/primitive/DoubleObjectHashMap$KeySet;
            aload 0 /* this */
            aload 2
            putfield org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1.val$result:[D
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/eclipse/collections/impl/map/mutable/primitive/DoubleObjectHashMap$KeySet$1;
    MethodParameters:
            Name  Flags
      this$0      final
      val$result  final

  public void value(double);
    descriptor: (D)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=3, args_size=2
        start local 0 // org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1 this
        start local 1 // double each
         0: .line 3737
            aload 0 /* this */
            getfield org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1.val$result:[D
            aload 0 /* this */
            getfield org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1.index:I
            dload 1 /* each */
            dastore
         1: .line 3738
            aload 0 /* this */
            dup
            getfield org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1.index:I
            iconst_1
            iadd
            putfield org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1.index:I
         2: .line 3739
            return
        end local 1 // double each
        end local 0 // org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    3     0  this  Lorg/eclipse/collections/impl/map/mutable/primitive/DoubleObjectHashMap$KeySet$1;
            0    3     1  each  D
    MethodParameters:
      Name  Flags
      each  
}
SourceFile: "DoubleObjectHashMap.java"
EnclosingMethod: org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet.toArray:()[D
NestHost: org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap
InnerClasses:
  private KeySet = org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet of org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap
  org.eclipse.collections.impl.map.mutable.primitive.DoubleObjectHashMap$KeySet$1