Java中Enum的使用

不念不忘少年蓝@ 2022-06-09 02:11 205阅读 0赞

package com.zoer.src;
    
    public enum WeekDay {
    	Mon_("Monday"), Tue_("Tuesday"), Wed_("Wednesday"), Thu_("Thursday"), Fri_(
    			"Friday"), Sat_("Saturday"), Sun_("Sunday");
    
    	private final String day;
    
    	private WeekDay(String day) {
    		System.out.println(day);
    		this.day = day;
    	}
    
    	public static void printDay(int i) {
    		switch (i) {
    		case 1:
    			System.out.println(WeekDay.Mon_);
    			break;
    		case 2:
    			System.out.println(WeekDay.Tue_);
    			break;
    		case 3:
    			System.out.println(WeekDay.Wed_);
    			break;
    		case 4:
    			System.out.println(WeekDay.Thu_);
    			break;
    		case 5:
    			System.out.println(WeekDay.Fri_);
    			break;
    		case 6:
    			System.out.println(WeekDay.Sat_);
    			break;
    		case 7:
    			System.out.println(WeekDay.Sun_);
    			break;
    		default:
    			System.out.println("wrong number!");
    		}
    	}
    
    	public String getDay() {
    		return day;
    	}
    }

上面的代码中生明了一个enum，枚举类型用来表示一组相同类型的常量。

代码中使用了private的构造函数【enum仅允许private的构造函数】。

Tue\_("Tuesday")，括号内的内容就是构造函数中的参数，比如传入Tuesday，则经过构造函数执行之后，Tue的day值就是Tuesday了。

ps：整个enum初始化的过程中，生明了几个值，则构造函数需要执行相应次数。

package com.zoer.src;
    
    public class T {
    
    	/**
    	 * @param args
    	 */
    	public static void main(String args[]) {
    		for (int i = 0; i < WeekDay.values().length; i++) {
    			WeekDay d = WeekDay.values()[i];
    			p(d);
    		}
    	}
    
    	public static void p(WeekDay d) {
    		System.out.println(d + "->" + d.getDay());
    	}
    }

输出：

Mon_->Monday
    Tue_->Tuesday
    Wed_->Wednesday
    Thu_->Thursday
    Fri_->Friday
    Sat_->Saturday
    Sun_->Sunday