java枚举

定义自己的枚举类

//用enum定义一个枚举类
public enum LampEnum{
	//指定构造参数调用相应的构造器，并实现其中的抽象方法，每个枚举值就是一个final static LampEnum 对象； 
	RED(30){
		public LampEnum nextLamp(){
			return YELLOW;
		};
	},GREEN(30){
		public LampEnum nextLamp(){
			return RED;
		};
	},YELLOW(5){
		public LampEnum nextLamp(){
			return GREEN;
		};
	};
	//构造器定义必须放在枚举值的后面，并且构造器只能用private修饰
	private LampEnum(){
		System.out.println("the first constroctor");
	};
	private LampEnum(int time){
		this.time = time;
	}
	
	private int time;
	
	public abstract LampEnum nextLamp();
	
}

普通类实现枚举

public abstract class LampClass {
	
	private LampClass(){};
	private LampClass(int time){
		this.time = time;
		System.out.println(this.time);
		
	}
	public final static LampClass RED = new LampClass(5){
		public LampClass nextLamp() {
			return YELLOW;
		}
	};
	
	public final static LampClass GREEN = new LampClass(){
		public LampClass nextLamp() {
			return RED;
		}
	};
	
	public final static LampClass YELLOW = new LampClass(){
		public LampClass nextLamp() {
			// TODO Auto-generated method stub
			return GREEN;
		}
	};
	private int time;
	public abstract LampClass nextLamp();
}

功能测试类

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public class EnumTest {
	public static void main(String[] args) {
		LampEnum green = LampEnum.GREEN;
		
		//返回两个枚举值的顺序之差。(前提是两个枚举值必须属于同一个枚举类，否则会抛出ClassCastException()异常)
		System.out.println(green.compareTo(LampEnum.YELLOW));
		
		//引用的枚举类中的那个枚举值
		System.out.println(green.name());
		
		//返回枚举值在枚举类中的顺序。这个顺序根据枚举值声明的顺序而定
		System.out.println(green.ordinal());
		
		//返回跟参数相同的枚举值得引用
		System.out.println(green.valueOf("YELLOW"));
		
		//返回所有的枚举值
		LampEnum[] le = green.values();
		System.out.println(le.length);
		//枚举可以用于switch语句
		switch (green) {
		case RED:
			System.out.println("it's red");
			break;
		case GREEN:
			System.out.println("it's green");
			break;
		case YELLOW:
			System.out.println("it's yellow");
			break;

		default:
			break;
		}
	}
}

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