JavaSE-枚举类

Posted 2020-06-11

package com.btp.t4;
/*
 * 一.枚举类
 * 1.如何自定义枚举类
 * 2.如何使用enum关键字定义枚举类
 *     >常用的方法:values()，valueOf(String name)
 *     >如何让枚举类实现接口：让不同的枚举类对象调用被重写的抽象方法，执行的效果不同。（相当于让每个对象重写抽象方法）
 */
public class TestSeason {

	public static void main(String[] args){
		Season spring=Season.SPRING;
		System.out.println(spring);
		spring.show();
		System.out.println(spring.getSeasonDesc());
		
		//1.values()
		Season1[] season=Season1.values();
		for(Object obj:season)
		{
			System.out.println(obj);
		}
		System.out.println();
		//2.valueOf(String name):要求传入的形参是枚举类对象的名字，否则报异常
		String str="SPRING";
		Season1 sea=Season1.valueOf(str);
		System.out.println(sea);
		System.out.println();
		
		sea.show();
		
		System.out.println();
		//Thread类的内部类State是一个枚举类
		Thread.State[] states=Thread.State.values();
		for(Object obj:states)
		{
			System.out.println(obj);
		}
		
	}
}

//自定义枚举类:如果只有一个对象，则是单例模式
class Season{
	//1.提供类的属性，声明为private final
	private final String seasonName;
	private final String seasonDesc;
	//2.声明为final的属性，在私有化构造器中初始化
	private Season(String seasonName,String seasonDesc){
		this.seasonName=seasonName;
		this.seasonDesc=seasonDesc;
	}
	//3.通过公共方法调用
	public String getSeasonName() {
		return seasonName;
	}
	public String getSeasonDesc() {
		return seasonDesc;
	}
	//4.创建枚举类的对象:将类的对象声明为public static final
	public static final Season SPRING=new Season("spring","春暖花开");
	public static final Season SUMMER=new Season("summer","夏日炎炎");
	public static final Season AUTUMN=new Season("autumn","秋高气爽");
	public static final Season WINTER=new Season("winter","白雪皑皑");
	
	@Override
	public String toString() {
		return "Season [seasonName=" + seasonName + ", seasonDesc=" + seasonDesc + "]";
	}
	public void show(){
		System.out.println("这是一个"+this.getSeasonName()+"季节！");
	}
}

//接口info
interface info{
	void show();
}


//用enum关键字定义枚举类
enum Season1 implements info{
	//成员要写在最前面
	//让不同的枚举类对象调用被重写的抽象方法，执行的效果不同。（相当于让每个对象重写抽象方法）
	SPRING("spring","春暖花开"){
		public void show(){
			System.out.println("春天在哪里？");
		}
	},
	SUMMER("summer","夏日炎炎"){
		public void show(){
			System.out.println("生如夏花");
		}
	},
	AUTUMN("autumn","秋高气爽"){
		public void show(){
			System.out.println("秋天是分手的季节");
		}
	},
	WINTER("winter","白雪皑皑"){
		public void show(){
			System.out.println("冬天里的一把火火");
		}
	};
	private final String seasonName;
	private final String seasonDesc;
	private Season1(String seasonName,String seasonDesc){
		this.seasonName=seasonName;
		this.seasonDesc=seasonDesc;
	}
	@Override
	public String toString() {
		return "Season [seasonName=" + seasonName + ", seasonDesc=" + seasonDesc + "]";
	}
	
//	public void show() {
//		// TODO 自动生成的方法存根
//		System.out.println("这是一个季节！");
//	}
	
}