JAVA的enum数据类型的应用详解(持续ing)

enum是很雷同class了的，只是一种比较特殊的class类而已，JAVA对以enum类进行了特殊处理。

简单应用1：

public enum WeekDay{//定义一个WeekDay
    MONDAY,
    TUESDAY,
    WEDNESDAY,
    THURSDAY,
    FRIDAY,
    SATURDAY, 
    SUNDAY//不需要带冒号
}

public class HelloWorld {

    public static void main(String[] args) {
    
        System.out.println(WeekDay.FRIDAY);//直接点，就可以点出来，并且作为离散值进行判断

    }
}

简单应用2：

enmu有属性

public enum WeekDay{
    MONDAY(1,"MONDAY","星期一"),
    TUESDAY(2,"TUESDAY","星期二"),
    WEDNESDAY(3,"WEDNESDAY","星期三"),
    THURSDAY(4,"THURSDAY","星期四"),
    FRIDAY(5,"THURSDAY","星期五"),
    SATURDAY(6,"SATURDAY","星期六"),
    SUNDAY(7,"SUNDAY","星期天");

    private int index;//数字索引
    private String descEN;//英语名称
    private String descCN;//汉语名称

    private WeekDay(int index,String descEN,String descCN){//必须写这个构造函数，相当于初始化实例
        this.index=index;
        this.descEN=descEN;
        this.descCN=descCN;
    }

    public String getDescCN(){//写一个get方法，获得汉语名称
        return this.descCN;
    }
}

public class HelloWorld {

    public static void main(String[] args) {
    
        System.out.println(WeekDay.FRIDAY);//直接点，就可以点出来，并且作为离散值进行判断

        System.out.println(WeekDay.SATURDAY.getDescCN());

    }
}    

常见用法3，一般是用来定义系统的错误标识

public enum ResultCodeEnum {
    SUCESS("0000","成功"),
    E9000("9000","缺少必要的字段"),
    E9001("9001","参数非法"),
    E9999("9999","系统内部异常，请联系管理员");

    private String ResultCode;
    private String ResultDesc;

    private ResultCodeEnum(String ResultCode,String ResultDesc){
        this.ResultCode = ResultCode;
        this.ResultCode = ResultDesc;
    }

    public String getResultDesc(){
        return this.ResultDesc;
    }
}