一.枚举介绍
1.枚举是一组常量的集合
2.理解：美剧属于一种特殊的类，里面只包含一组有限的特定的对象
1.自定义枚举实现
1.不需要提供Set方法，枚举对象值通常为只读。
2.对枚举对象/属性使用final和static关键字修饰，实现底层优化
3.枚举对象名通常使用全部大写，常量的命名规范
4.枚举·对象根据需要，可以有一到多个属性
（1）示例
package com.demo;
import javax.sound.midi.Soundbank;
public class Enum01 {
public static void main(String[] args) {
System.out.println(Season.SPRING);
System.out.println(Season.SUMMER);
System.out.println(Season.AUTUMN);
System.out.println(Season.WINTER);
}
}
//演示自定义枚举实现
class Season{
private String name;
private String desc;//描述特性
//1.将构造器私有化，目的防止直接new出来
private Season(String name, String desc) {
this.name = name;
this.desc = desc;
}
//2.去掉set方法，只能读取，不能修改属性
public String getName() {
return name;
}
public String getDesc() {
return desc;
}
//3.在season内部创建固定的对象
//定义了四个对象
// public static Season SPRING=new Season("春天","温暖");
// public static Season SUMMER=new Season("夏天","炎热");
// public static Season AUTUMN=new Season("秋天","凉爽");
// public static Season WINTER=new Season("冬天","寒冷");
//最终优化，加入final
public static final Season SPRING=new Season("春天","温暖");
public static final Season SUMMER=new Season("夏天","炎热");
public static final Season AUTUMN=new Season("秋天","凉爽");
public static final Season WINTER=new Season("冬天","寒冷");
//重写toString方法
@Override
public String toString() {
return "Season{" +
"name='" + name + '\'' +
", desc='" + desc + '\'' +
'}';
}
}（2）测试结果
2.enum关键字实现枚举
如果使用enum关键字来实现枚举类
1.使用关键字enum替换class
2.public static final Season02 SPRING=new Season02(“春天”,“温暖”);可替换为 SPRING(“春天”,“温暖”),//解读：常量名（实参列表）
3.如果有多个常量使用逗号间隔即可
4.如果使用enum关键字实现枚举，要求将定义的常量对象写下前面
（1）示例
package com.demo;
public class Enum02 {
public static void main(String[] args) {
System.out.println(Season.SPRING);
System.out.println(Season.SUMMER);
System.out.println(Season.AUTUMN);
System.out.println(Season.WINTER);
}
}
//演示使用enum关键字来实现枚举类
enum Season02{
//如果使用enum关键字来实现枚举类
//1.使用关键字enum替换class
//2.public static final Season02 SPRING=new Season02("春天","温暖");可替换为
SPRING("春天","温暖"),//解读：常量名（实参列表）
//3.如果有多个常量使用逗号间隔即可
SUMMER("夏天","炎热"),
AUTUMN("秋天","凉爽"), WINTER("冬天","寒冷");
//4.如果使用enum关键字实现枚举，要求将定义的常量对象写下前面
private String name;
private String desc;//描述特性
//1.将构造器私有化，目的防止直接new出来
private Season02(String name, String desc) {
this.name = name;
this.desc = desc;
}
//2.去掉set方法，只能读取，不能修改属性
public String getName() {
return name;
}
public String getDesc() {
return desc;
}
//3.在season内部创建固定的对象
//定义了四个对象
// public static Season SPRING=new Season("春天","温暖");
// public static Season SUMMER=new Season("夏天","炎热");
// public static Season AUTUMN=new Season("秋天","凉爽");
// public static Season WINTER=new Season("冬天","寒冷");
//最终优化，加入final
// public static final Season02 SPRING=new Season02("春天","温暖");
// public static final Season02 SUMMER=new Season02("夏天","炎热");
// public static final Season02 AUTUMN=new Season02("秋天","凉爽");
// public static final Season02 WINTER=new Season02("冬天","寒冷");
//重写toString方法
@Override
public String toString() {
return "Season{" +
"name='" + name + '\'' +
", desc='" + desc + '\'' +
'}';
}
}（2）测试结果
3.enum关键字注意事项
1.当我i们使用enum关键字开发一个枚举类时，默认会继承Enum类
2.传统的public static final Season02 SPRING=new Season02("春天","温暖");，这里要知道他调用的是哪个构造器
3.如果使用无参构造器创建枚举对象，则实参列表和小括号都可以省略.
4.当有多个枚举对象时，使用逗号间隔，最后有一个分号结尾
5.枚举对象必须放在枚举类的行首
（1）示例
package com.demo;
public class Enum02 {
public static void main(String[] args) {
System.out.println(Season.SPRING);
System.out.println(Season.SUMMER);
System.out.println(Season.AUTUMN);
System.out.println(Season.WINTER);
}
}
//演示使用enum关键字来实现枚举类
enum Season02{
//如果使用enum关键字来实现枚举类
//1.使用关键字enum替换class
//2.public static final Season02 SPRING=new Season02("春天","温暖");可替换为
SPRING("春天","温暖"),//解读：常量名（实参列表）
//3.如果有多个常量使用逗号间隔即可
SUMMER("夏天","炎热"),
AUTUMN("秋天","凉爽"), WINTER("冬天","寒冷"),
//3.如果使用无参构造器创建枚举对象，则实参列表和小括号都可以省略.两种写法
HAHA,//调用无参构造器
HAHAHA();//调用无参构造器
//4.如果使用enum关键字实现枚举，要求将定义的常量对象写下前面
private String name;
private String desc;//描述特性
//1.将构造器私有化，目的防止直接new出来
private Season02(String name, String desc) {
this.name = name;
this.desc = desc;
}
private Season02() {
//无参构造器
}
//2.去掉set方法，只能读取，不能修改属性
public String getName() {
return name;
}
public String getDesc() {
return desc;
}
//3.在season内部创建固定的对象
//定义了四个对象
// public static Season SPRING=new Season("春天","温暖");
// public static Season SUMMER=new Season("夏天","炎热");
// public static Season AUTUMN=new Season("秋天","凉爽");
// public static Season WINTER=new Season("冬天","寒冷");
//最终优化，加入final
// public static final Season02 SPRING=new Season02("春天","温暖");
// public static final Season02 SUMMER=new Season02("夏天","炎热");
// public static final Season02 AUTUMN=new Season02("秋天","凉爽");
// public static final Season02 WINTER=new Season02("冬天","寒冷");
//重写toString方法
@Override
public String toString() {
return "Season{" +
"name='" + name + '\'' +
", desc='" + desc + '\'' +
'}';
}
}到此这篇关于Java实例讲解枚举enum的实现的文章就介绍到这了,更多相关Java枚举内容请搜索编程网以前的文章或继续浏览下面的相关文章希望大家以后多多支持编程网！
