java 问题,玖举就是常量,与public static final有什么区别?为什么要用玖举?
答案:2 悬赏:60 手机版
解决时间 2021-11-11 21:40
- 提问者网友:川水往事
- 2021-11-11 12:22
java 问题,玖举就是常量,与public static final有什么区别?为什么要用玖举?
最佳答案
- 五星知识达人网友:鸽屿
- 2021-11-11 12:41
enum就是为了让你方便使用常量而存在的,
例如:
public enum A {
A1("12", 12),
A2("34", 34),
A3("56", 56);
private A(String s, int i) {
S = s;
I = i;
}
public final String S;
public final int I;
}和这种写法:
public class A {
private A (String s, int i) {
S = s;
I = i;
}
public final String S;
public final int I;
public static final A A1 = new A("12", 12);
public static final A A2 = new A("34", 34);
public static final A A3 = new A("56", 56);
} 比起来,你觉得那种更方便?
例如:
public enum A {
A1("12", 12),
A2("34", 34),
A3("56", 56);
private A(String s, int i) {
S = s;
I = i;
}
public final String S;
public final int I;
}和这种写法:
public class A {
private A (String s, int i) {
S = s;
I = i;
}
public final String S;
public final int I;
public static final A A1 = new A("12", 12);
public static final A A2 = new A("34", 34);
public static final A A3 = new A("56", 56);
} 比起来,你觉得那种更方便?
全部回答
- 1楼网友:青灯有味
- 2021-11-11 12:52
常量是一旦定义就不可修改的值,在开发中,如果有多个常量,需要定义多个常量;如:
public static final String MONDAY="周一";
public static final String TUESDAY ="周二";
public static final String WEDNESDAY="周三";
public static final String THURSDAY="周四";
public static final String FRIDAY="周五;
public static final String SATURDAY ="周六";
public static final String SUNDAY ="周日";
这样定义,显然比较费劲,枚举你可以理解为是对常量的封装,它是一个特殊的类。可以有自己自定义的方法,自定义的属性和构造函数。其次,变量的类型可以是枚举类型,这样就限定了变量的取值范围。如:
定义一个枚举
public enum WEEK{
MONDAY("周一"),TUESDAY(),WEDNESDAY,THURSDAY,FRIDAY,SATURDAY,SUNDAY;
//定义私有构造函数,给这些常量赋值
private String str;
public String getStr(){
return this.str;
}
}
定义一个变量为枚举类型
WEEK w = WEEK.MONDAY;
System.out.println(s.getStr());
public static final String MONDAY="周一";
public static final String TUESDAY ="周二";
public static final String WEDNESDAY="周三";
public static final String THURSDAY="周四";
public static final String FRIDAY="周五;
public static final String SATURDAY ="周六";
public static final String SUNDAY ="周日";
这样定义,显然比较费劲,枚举你可以理解为是对常量的封装,它是一个特殊的类。可以有自己自定义的方法,自定义的属性和构造函数。其次,变量的类型可以是枚举类型,这样就限定了变量的取值范围。如:
定义一个枚举
public enum WEEK{
MONDAY("周一"),TUESDAY(),WEDNESDAY,THURSDAY,FRIDAY,SATURDAY,SUNDAY;
//定义私有构造函数,给这些常量赋值
private String str;
public String getStr(){
return this.str;
}
}
定义一个变量为枚举类型
WEEK w = WEEK.MONDAY;
System.out.println(s.getStr());
我要举报
如以上问答信息为低俗、色情、不良、暴力、侵权、涉及违法等信息,可以点下面链接进行举报!
大家都在看
推荐资讯