一、枚举介绍

二、自定义类实现枚举

package com.enum_;

/**
 * @author Gao YongHao
 * @version 1.0
 */
public class DefineByUser {
    public static void main(String[] args) {
        System.out.println(Season.AUTUMN);
    }
}

class Season { // 类
    public static final Season SPRING = new Season("Spring", "温暖");
    public static final Season SUMMER = new Season("Summer", "炎热");
    public static final Season AUTUMN = new Season("Autumn", "凉爽");
    public static final Season WINTER = new Season("Winter", "寒冷");


    private String name;
    private String desc;
    // 1. 将构造器私有化，目的防止 外部直接 new
    // 2. 去掉setXxx方法，防止属性被修改
    // 3. 在 Season 内部，直接创建固定的对象
    private Season(String name, String desc) {
        this.name = name;
        this.desc = desc;
    }

    public String getName() {
        return name;
    }

    public String getDesc() {
        return desc;
    }

    @Override
    public String toString() {
        return "Season{" +
                "name='" + name + '\'' +
                ", desc='" + desc + '\'' +
                '}';
    }
}

三、enum关键字实现枚举

3.1 enum案例

package com.enum_;

/**
 * @author Gao YongHao
 * @version 1.0
 */
public class DefineByEnum {
    public static void main(String[] args) {
        System.out.println(Season2.SPRING);
    }
}

enum Season2 {

    // 如果使用了 enum 来实现枚举类
    // 1. 使用关键字 enum 替代 class
    // 2. public static final Season2 SPRING = new Season2("Spring","温暖");
    // 直接使用
    // SPRING("Spring", "温暖"); 解读  常量名(实参列表)
    // 3. 如果有多个常量(对象)   使用 , 号间隔即可
    // 4. 如果使用enum来实现枚举，要求将定义的常量对象，写在前面
    SPRING("Spring", "温暖"), SUMMER("Summer", "炎热"), AUTUMN("Autumn", "凉爽"),
    WINTER("冬天", "寒冷");
    private String name;
    private String desc;

    Season2(String name, String desc) {
        this.name = name;
        this.desc = desc;
    }

    public String getName() {
        return name;
    }

    public String getDesc() {
        return desc;
    }
}

3.2 enum关键字实现枚举注意事项

• 要求所有的构造器均为 private 修饰（默认的无参构造器也为 private 修饰）
• enum反编译的信息如下
  

3.3 enum常用方法说明

3.4 enum实现接口

四、JDK内置的基本注解类型

4.1 注解的理解

4.2 基本的Annotation介绍

4.3 @Override

4.4 @Deprecated

4.5 @SuppressWarnings

五、元注解：对注解进行注解

5.1 元注解的基本介绍

5.2 @Retention

5.3 @Target

5.4 @Documented

5.5 Inherited注解

细节

增强for循环

public class Test{
    public static void main(String[] args){
        Teacher[] teas = {new Teacher("aa","32"),new Teacher("bb","32"),new Teacher("bb","32")};
        for(Teacher t:teas){ // 增强 for 循环，类似于python的for循环遍历(缺点无法获知当前的index)
            System.out.println("name:"+t.name + " age:" + t.age);
        }
        
    }
}

class Teacher{
    public String name;
    public int age;
    public Teacher(String name,int age){
        this.name = name;
        this.age = age;
    }
}