public static enum MyEnum
通过反汇编枚举得到的字节码，可以看出枚举上的values()方法只是返回一个包含所有已声明枚举常量的private static数组的副本。这个名为ENUM$VALUES的数组在静态初始化块中填充。
DaysOfTheWeek.java
public enum DaysOfTheWeek {
MONDAY,
TUESDAY,
WEDNESDAY,
THURSDAY,
FRIDAY,
SATURDAY,
SUNDAY
}
DaysOfTheWeek.java反汇编
在静态块之后，字节码标记为0-92的部分初始化了枚举常量，字节码标记为94-139的部分将这些常量放入一个数组中，而字节码标记为140的部分则将该数组赋值给类的ENUM$VALUES静态字段。在values()方法中的代码仅通过调用System.arraycopy在ENUM$VALUES字段上创建了一个副本并返回该副本。
Compiled from "DaysOfTheWeek.java"
public final class DaysOfTheWeek extends java.lang.Enum{
public static final DaysOfTheWeek MONDAY;
public static final DaysOfTheWeek TUESDAY;
public static final DaysOfTheWeek WEDNESDAY;
public static final DaysOfTheWeek THURSDAY;
public static final DaysOfTheWeek FRIDAY;
public static final DaysOfTheWeek SATURDAY;
public static final DaysOfTheWeek SUNDAY;
static {};
Code:
0: new #1; //class DaysOfTheWeek
3: dup
4: ldc #18; //String MONDAY
6: iconst_0
7: invokespecial #19; //Method "<init>":(Ljava/lang/String;I)V
10: putstatic #23; //Field MONDAY:LDaysOfTheWeek;
13: new #1; //class DaysOfTheWeek
16: dup
17: ldc #25; //String TUESDAY
19: iconst_1
20: invokespecial #19; //Method "<init>":(Ljava/lang/String;I)V
23: putstatic #26; //Field TUESDAY:LDaysOfTheWeek;
26: new #1; //class DaysOfTheWeek
29: dup
30: ldc #28; //String WEDNESDAY
32: iconst_2
33: invokespecial #19; //Method "<init>":(Ljava/lang/String;I)V
36: putstatic #29; //Field WEDNESDAY:LDaysOfTheWeek;
39: new #1; //class DaysOfTheWeek
42: dup
43: ldc #31; //String THURSDAY
45: iconst_3
46: invokespecial #19; //Method "<init>":(Ljava/lang/String;I)V
49: putstatic #32; //Field THURSDAY:LDaysOfTheWeek;
52: new #1; //class DaysOfTheWeek
55: dup
56: ldc #34; //String FRIDAY
58: iconst_4
59: invokespecial #19; //Method "<init>":(Ljava/lang/String;I)V
62: putstatic #35; //Field FRIDAY:LDaysOfTheWeek;
65: new #1; //class DaysOfTheWeek
68: dup
69: ldc #37; //String SATURDAY
71: iconst_5
72: invokespecial #19; //Method "<init>":(Ljava/lang/String;I)V
75: putstatic #38; //Field SATURDAY:LDaysOfTheWeek;
78: new #1; //class DaysOfTheWeek
81: dup
82: ldc #40; //String SUNDAY
84: bipush 6
86: invokespecial #19; //Method "<init>":(Ljava/lang/String;I)V
89: putstatic #41; //Field SUNDAY:LDaysOfTheWeek;
92: bipush 7
94: anewarray #1; //class DaysOfTheWeek
97: dup
98: iconst_0
99: getstatic #23; //Field MONDAY:LDaysOfTheWeek;
102: aastore
103: dup
104: iconst_1
105: getstatic #26; //Field TUESDAY:LDaysOfTheWeek;
108: aastore
109: dup
110: iconst_2
111: getstatic #29; //Field WEDNESDAY:LDaysOfTheWeek;
114: aastore
115: dup
116: iconst_3
117: getstatic #32; //Field THURSDAY:LDaysOfTheWeek;
120: aastore
121: dup
122: iconst_4
123: getstatic #35; //Field FRIDAY:LDaysOfTheWeek;
126: aastore
127: dup
128: iconst_5
129: getstatic #38; //Field SATURDAY:LDaysOfTheWeek;
132: aastore
133: dup
134: bipush 6
136: getstatic #41; //Field SUNDAY:LDaysOfTheWeek;
139: aastore
140: putstatic #43; //Field ENUM$VALUES:[LDaysOfTheWeek;
143: return
public static DaysOfTheWeek[] values();
Code:
0: getstatic #43; //Field ENUM$VALUES:[LDaysOfTheWeek;
3: dup
4: astore_0
5: iconst_0
6: aload_0
7: arraylength
8: dup
9: istore_1
10: anewarray #1; //class DaysOfTheWeek
13: dup
14: astore_2
15: iconst_0
16: iload_1
17: invokestatic #51; //Method java/lang/System.arraycopy:(Ljava/lang/Object;ILjava/lang/Object;II)V
20: aload_2
21: areturn
public static DaysOfTheWeek valueOf(java.lang.String);
Code:
0: ldc #1; //class DaysOfTheWeek
2: aload_0
3: invokestatic #59; //Method java/lang/Enum.valueOf:(Ljava/lang/Class;Ljava/lang/String;)Ljava/lang/Enum;
6: checkcast #1; //class DaysOfTheWeek
9: areturn
}
您提供的链接（其中包含私有getValues方法）来自Apache Harmony（版本6，这是一个开源的Java SE）。他们对Oracle的Enum类有不同的实现（没有私有的getValues方法）。
在编写本文时，Oracle Java（版本1.6.0-21）具有valueOf（Class<T> enumType，String name）。以下是它的实现：
/**
* Returns the enum constant of the specified enum type with the
* specified name. The name must match exactly an identifier used
* to declare an enum constant in this type. (Extraneous whitespace
* characters are not permitted.)
*
* @param enumType the <tt>Class</tt> object of the enum type from which
* to return a constant
* @param name the name of the constant to return
* @return the enum constant of the specified enum type with the
* specified name
* @throws IllegalArgumentException if the specified enum type has
* no constant with the specified name, or the specified
* class object does not represent an enum type
* @throws NullPointerException if <tt>enumType</tt> or <tt>name</tt>
* is null
* @since 1.5
*/
public static <T extends Enum<T>> T valueOf(Class<T> enumType,
String name) {
T result = enumType.enumConstantDirectory().get(name);
if (result != null)
return result;
if (name == null)
throw new NullPointerException("Name is null");
throw new IllegalArgumentException(
"No enum const " + enumType +"." + name);
}
本质上，这是Apache实现他们的valueOf不同的方式。
Enum（或enum）有一个名为 values() 的公共静态方法，该方法返回在enum内声明的枚举值常量。这是由编译器填充的。
sun.com 网站现在都变成了 oracle.com。我们也不妨跟进一下... - Buhake Sindivalues()方法是根据定义由编译器添加的。编译器在创建枚举时会自动添加一些特殊的方法。例如，它们有一个静态的
values方法，该方法按声明顺序返回包含枚举所有值的数组。