Java基础之《枚举类》

枚举类是一种特殊的class，使用关键字enum定义。
枚举类里的枚举值就是这个枚举类的对象，拥有这个枚举类所定义的属性和方法。

例子程序：EnumTest.java
最简单的枚举定义和遍历

package com.test.enumtest;

//枚举类-常量
public enum EnumTest {
	//定义枚举值-常量
	sunday,
	monday,
	tuesday,
	wednesday,
	thursday,
	friday,
	saturday;
	
	public static void main(String args[]) {
		
		//获得常量
		/*通过values()获得枚举值的数组*/
		for (EnumTest e : EnumTest.values()) {
			System.out.println(e.toString());
		}
		System.out.println("===============");
		//效果一样
		for (EnumTest e : EnumTest.values()) {
			System.out.println(e);
		}
		System.out.println("===============");
		System.out.println(EnumTest.thursday);
	}
}

运行结果：

sunday

monday

tuesday

wednesday

thursday

friday

saturday

===============

sunday

monday

tuesday

wednesday

thursday

friday

saturday

===============

thursday

例子程序：EnumTest1.java

带数值的枚举值，以及遍历数值

package com.test.enumtest;

//枚举类-常量带数值
public enum EnumTest1 {
	//定义枚举值-常量带数值
	sunday(99),
	monday(100),
	tuesday(101),
	wednesday(102),
	thursday(103),
	friday(104),
	saturday(105);
	
	private final int value;
	
	public int getValue() {
		return value;
	}
	
	//构造方法
	private EnumTest1(int value) {
		this.value = value;
	}
	
	public static void main(String args[]) {
		for (EnumTest1 e : EnumTest1.values()) {
			System.out.println(e);
		}
		System.out.println("===============");
		for (EnumTest1 e : EnumTest1.values()) {
			System.out.println(e.getValue());
		}
	}
}

运行结果：

sunday

monday

tuesday

wednesday

thursday

friday

saturday

===============

99

100

101

102

103

104

105

例子程序：EnumTest2.java

带键值对的枚举值，以及遍历

package com.test.enumtest;

//枚举类-键值对
public enum EnumTest2 {
	//定义枚举值-键值对
	sunday(99,"sun"),
	monday(100,"mon"),
	tuesday(101,"tues"),
	wednesday(102,"wed"),
	thursday(103,"thur"),
	friday(104,"fri"),
	saturday(105,"sat");
	
	private final int code;
	private final String value;
	
	private EnumTest2(int code, String value) {
		this.code = code;
		this.value = value;
	}
	
	public int getCode() {
		return code;
	}
	
	public String getValue() {
		return value;
	}
	
	public static void main(String args[]) {
		for (EnumTest2 e : EnumTest2.values()) {
			System.out.println(e + " " + e.getCode() + " " + e.getValue());
		}
	}
}

运行结果：

sunday 99 sun

monday 100 mon

tuesday 101 tues

wednesday 102 wed

thursday 103 thur

friday 104 fri

saturday 105 sat

例子程序：EnumTest3.java

使用Map保存枚举值，以及遍历

package com.test.enumtest;

import java.util.HashMap;
import java.util.Map;

//枚举类-键值对（装入一个HashMap内）
public enum EnumTest3 {
	//定义枚举值-键值对
	sunday(99,"sun"),
	monday(100,"mon"),
	tuesday(101,"tues"),
	wednesday(102,"wed"),
	thursday(103,"thur"),
	friday(104,"fri"),
	saturday(105,"sat");
	
	private final int code;
	private final String value;
	
	private EnumTest3(int code, String value) {
		this.code = code;
		this.value = value;
	}
	
	public int getCode() {
		return code;
	}
	
	public String getValue() {
		return value;
	}
	
	private static Map<Integer, String> param = new HashMap<Integer, String>();
	
	public static Map<Integer, String> getParam() {
		return param;
	}
	
	//静态语句块初始化HashMap
	static {
		for (EnumTest3 e : EnumTest3.values()) {
			param.put(e.getCode(), e.getValue());
		}
	}
	
	public static void main (String args[]) {
		//遍历Map
		for (Map.Entry<Integer, String> m : EnumTest3.getParam().entrySet()) {
			System.out.println("key:" + m.getKey() + " value:" + m.getValue());
		}
	}
}

运行结果：

key:102 value:wed

key:103 value:thur

key:100 value:mon

key:101 value:tues

key:99 value:sun

key:104 value:fri

key:105 value:sat