这是一个枚举：

enum Foo { X }

我使用以下命令编译和反汇编(在Java 8u60上)：

javac Foo.java && javap -c -p Foo

这是我得到的输出：

final class Foo extends java.lang.Enum<Foo> {
  public static final Foo X;

  private static final Foo[] $VALUES;

  public static Foo[] values();
    Code:
       0: getstatic     #1                  // Field $VALUES:[LFoo;
       3: invokevirtual #2                  // Method "[LFoo;".clone:()Ljava/lang/Object;
       6: checkcast     #3                  // class "[LFoo;"
       9: areturn

  public static Foo valueOf(java.lang.String);
    Code:
       0: ldc           #4                  // class Foo
       2: aload_0
       3: invokestatic  #5                  // Method java/lang/Enum.valueOf:(Ljava/lang/Class;Ljava/lang/String;)Ljava/lang/Enum;
       6: checkcast     #4                  // class Foo
       9: areturn

  private Foo(); // <--- here
    Code:
       0: aload_0
       1: aload_1
       2: iload_2
       3: invokespecial #6                  // Method java/lang/Enum."<init>":(Ljava/lang/String;I)V
       6: return

  static {};
    Code:
       0: new           #4                  // class Foo
       3: dup
       4: ldc           #7                  // String X
       6: iconst_0
       7: invokespecial #8                  // Method "<init>":(Ljava/lang/String;I)V
      10: putstatic     #9                  // Field X:LFoo;
      13: iconst_1
      14: anewarray     #4                  // class Foo
      17: dup
      18: iconst_0
      19: getstatic     #9                  // Field X:LFoo;
      22: aastore
      23: putstatic     #1                  // Field $VALUES:[LFoo;
      26: return
}

我的困惑是用于实例化每个枚举常量的私有构造函数.反汇编显示它不带参数(私有Foo();),但肯定会带参数.例如,您可以看到读取传递的枚举常量名称和序号以及this指针的加载指令,并将它们传递给the superclass constructor,这需要它们.静态初始化程序块中的代码还显示它在调用构造函数之前将这些参数压入堆栈.

现在我假设这只是javap中一个不起眼的错误,但是当我使用Eclipse的编译器编译完全相同的枚举并使用javap反汇编时,构造函数完全相同,除了参数显示：

final class Foo extends java.lang.Enum<Foo> {
  public static final Foo X;

  private static final Foo[] ENUM$VALUES;

  static {};
    Code:
       0: new           #1                  // class Foo
       3: dup
       4: ldc           #12                 // String X
       6: iconst_0
       7: invokespecial #13                 // Method "<init>":(Ljava/lang/String;I)V
      10: putstatic     #17                 // Field X:LFoo;
      13: iconst_1
      14: anewarray     #1                  // class Foo
      17: dup
      18: iconst_0
      19: getstatic     #17                 // Field X:LFoo;
      22: aastore
      23: putstatic     #19                 // Field ENUM$VALUES:[LFoo;
      26: return

  private Foo(java.lang.String,int); // <--- here
    Code:
       0: aload_0
       1: aload_1
       2: iload_2
       3: invokespecial #23                 // Method java/lang/Enum."<init>":(Ljava/lang/String;I)V
       6: return

  public static Foo[] values();
    Code:
       0: getstatic     #19                 // Field ENUM$VALUES:[LFoo;
       3: dup
       4: astore_0
       5: iconst_0
       6: aload_0
       7: arraylength
       8: dup
       9: istore_1
      10: anewarray     #1                  // class Foo
      13: dup
      14: astore_2
      15: iconst_0
      16: iload_1
      17: invokestatic  #27                 // Method java/lang/System.arraycopy:(Ljava/lang/Object;ILjava/lang/Object;II)V
      20: aload_2
      21: areturn

  public static Foo valueOf(java.lang.String);
    Code:
       0: ldc           #1                  // class Foo
       2: aload_0
       3: invokestatic  #35                 // Method java/lang/Enum.valueOf:(Ljava/lang/Class;Ljava/lang/String;)Ljava/lang/Enum;
       6: checkcast     #1                  // class Foo
       9: areturn
}

我的问题是：javac编译的枚举和Eclipse编译的枚举之间有什么不同,导致javap不显示javac编译的枚举的构造函数参数？这是一个错误(在javap,javac或Eclipse中)？