java 枚举类

在 java 中，我们一般用枚举类来定义对象是有限的并且固定的类，比如一年四季，它只有4个对象

 

下面介绍枚举类的常见用法，以棋手等级分和等级名称为例

package nice.com.jenum;

public enum ChessGrade {
	
	firstChessGrade(1900,"一级棋手"),
	secondChessGrade(1800,"二级棋手"),
	threeChessGrade(1700,"三级棋手"),
	fourChessGrade(1600,"四级棋手"),
	fiveChessGrade(1500,"五级棋手"),
	sixChessGrade(1400,"六级棋手"),
	sevenChessGrade(1300,"七级棋手"),
	eightChessGrade(1200,"八级棋手"),
	nineChessGrade(1000,"九级棋手"),
	tenChessGrade(0,"十级棋手");
	
    private int grade;   //等级分
    private String ChessName;  //等级名称
    
    private ChessGrade(int grade,String ChessName){
    	this.grade=grade;
    	this.ChessName=ChessName;
    }
    
    public int getGrade(){
    	return this.grade;
    }
    
    public String getChessName(){
    	return this.ChessName;
    }
    
    //根据传入的 等级分 返回 等级名称
    public static String getChessNameByGrade(int grade){
    	for(ChessGrade cg:ChessGrade.values()){
    		if(cg.getGrade()==grade){
    			return cg.getChessName();
    		}
    	}
    	return null;
    }
    
    //根据 等级名称 获取 等级分
    public static int getGradeByChessName(String ChessName){
    	for(ChessGrade cg:ChessGrade.values()){
    		if(ChessName.equals(cg.getChessName())){
    			return cg.getGrade();
    		}
    	}
		return 0;  // 默认值
    } 

}

通过调用 getChessNameByGrade 或 getGradeByChessName 方法来实现相关功能

 

测试代码如下

package nice.com;

import nice.com.jenum.ChessGrade;

public class Test01 {

	public static void main(String[] args) {

		//输出  一级棋手 
		System.out.println(ChessGrade.getChessNameByGrade(1900));
		
		//输出等级分  1300
		System.out.println(ChessGrade.getGradeByChessName("七级棋手"));
	}

}