1. 枚举类的说明:
* 1.枚举类的理解:类的对象只有有限个,确定的。我们称此类为枚举类
* 2.当需要定义一组常量时,强烈建议使用枚举类
* 3.如果枚举类中只一个对象,则可以作为单例模式的实现方式。
2. 如何自定义枚举类?步骤:
//自定义枚举类 class Season{ //1.声明Season对象的属性:private final修饰 private final String seasonName; private final String seasonDesc; //2.私化类的构造器,并给对象属性赋值 private Season(String seasonName,String seasonDesc){ this.seasonName = seasonName; this.seasonDesc = seasonDesc; } //3.提供当前枚举类的多个对象:public static final的 public static final Season SPRING = new Season("春天","春暖花开"); public static final Season SUMMER = new Season("夏天","夏日炎炎"); public static final Season AUTUMN = new Season("秋天","秋高气爽"); public static final Season WINTER = new Season("冬天","冰天雪地"); //4.其他诉求1:获取枚举类对象的属性 public String getSeasonName() { return seasonName; } public String getSeasonDesc() { return seasonDesc; } //4.其他诉求1:提供toString() @Override public String toString() { return "Season{" + "seasonName=‘" + seasonName + ‘\‘‘ + ", seasonDesc=‘" + seasonDesc + ‘\‘‘ + ‘}‘; } }
3. jdk 5.0 新增使用enum定义枚举类。步骤:
//使用enum关键字枚举类 enum Season1 { //1.提供当前枚举类的对象,多个对象之间用","隔开,末尾对象";"结束 SPRING("春天","春暖花开"), SUMMER("夏天","夏日炎炎"), AUTUMN("秋天","秋高气爽"), WINTER("冬天","冰天雪地"); //2.声明Season对象的属性:private final修饰 private final String seasonName; private final String seasonDesc; //2.私化类的构造器,并给对象属性赋值 private Season1(String seasonName,String seasonDesc){ this.seasonName = seasonName; this.seasonDesc = seasonDesc; } //4.其他诉求1:获取枚举类对象的属性 public String getSeasonName() { return seasonName; } public String getSeasonDesc() { return seasonDesc; } }
4. 使用enum定义枚举类之后,枚举类常用方法:(继承于java.lang.Enum类)
Season1 summer = Season1.SUMMER; //toString():返回枚举类对象的名称 System.out.println(summer.toString()); // System.out.println(Season1.class.getSuperclass()); System.out.println("****************"); //values():返回所的枚举类对象构成的数组 Season1[] values = Season1.values(); for(int i = 0;i < values.length;i++){ System.out.println(values[i]); } System.out.println("****************"); Thread.State[] values1 = Thread.State.values(); for (int i = 0; i < values1.length; i++) { System.out.println(values1[i]); } //valueOf(String objName):返回枚举类中对象名是objName的对象。 Season1 winter = Season1.valueOf("WINTER"); //如果没objName的枚举类对象,则抛异常:IllegalArgumentException // Season1 winter = Season1.valueOf("WINTER1"); System.out.println(winter);
5. 使用enum定义枚举类之后,如何让枚举类对象分别实现接口:
interface Info{ void show(); } //使用enum关键字枚举类 enum Season1 implements Info{ //1.提供当前枚举类的对象,多个对象之间用","隔开,末尾对象";"结束 SPRING("春天","春暖花开"){ @Override public void show() { System.out.println("春天在哪里?"); } }, SUMMER("夏天","夏日炎炎"){ @Override public void show() { System.out.println("宁夏"); } }, AUTUMN("秋天","秋高气爽"){ @Override public void show() { System.out.println("秋天不回来"); } }, WINTER("冬天","冰天雪地"){ @Override public void show() { System.out.println("大约在冬季"); } }; }
原文:https://www.cnblogs.com/qiu-hua/p/13177159.html