Java第九章枚举&注解
九、枚举&注解
枚举：
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//枚举类 class Season{ //1.提供类的属性，声明为private final private final String seasonName; private final String seasonDesc; //2.声明为final的属性，在构造器中初始化 private Season(String seasonName,String seasonDesc){ this.seasonName = seasonName; this.seasonDesc = seasonDesc; } //3.通过公共的方法来调用属性 public String getSeasonName() { return seasonName; } public String getSeasonDesc() { return seasonDesc; } //4.创建枚举类的对象：将类的对象声明public static final public static final Season SPRING = new Season("spring","春暖花开"); public static final Season SUMMER = new Season("summer","夏日炎炎"); public static final Season AUTOMN = new Season("autumn","秋高气爽"); public static final Season WINTER = new Season("winter","白雪皑皑"); @Override public String toString() { return "Season [seasonName=" + seasonName + ", seasonDesc=" + seasonDesc + "]"; } public void show(){ System.out.println("这是一个季节"); }
enum关键字定义枚举类
常用的方法：value() valueOf(String name)
1.values() Season1[] season = Season1.values(); for(int i = 0;i < season.length;i++){ System.out.println(season[i]); } 2.valueOf(String name):要求传入的形参name是枚举类对象的名字 String str = "SPRING"; Season1 sea = Season1.valueOf(str);
让枚举类是实现接口：可以让不同的枚举类的对象调用被重写的抽象方法，执行的效果不同
enum Season extends ss{ SPRING("spring","春暖花开"){ public void show(){ System.out.println("春天"); } }, SUMMER("summer","夏日炎炎"){ public void show(){ System.out.println("夏天"); } }, AUTOMN("autumn","秋高气爽"){ public void show(){ System.out.println("秋天"); } }, WINTER("winter","白雪皑皑"){ public void show(){ System.out.println("冬天"); } }; private String seasonName; private String seasonDesc; private Season(String seasonName,String seasonDesc){ this.seasonName = seasonName; this.seasonDesc = seasonDesc; } public String getSeasonName() { return seasonName; } public String getSeasonDesc() { return seasonDesc; } public String toString() { return "Season [seasonName=" + seasonName + ", seasonDesc=" + seasonDesc + "]"; }
注解annotation
1.JDK内置的基本注解类型（3个）
@Override:限定重写父类的方法，该注释只能用于方法
@Deprecated：用于表示某个程序元素(类，方法等)已过时
@SuppressWarnings:抑制编译器警告
2.自定义注解类型
public @interface XX{
String value() default "hellow";
}
@XX(value = "xxx")
3.对注解进行注解(4个)(原注解)
4.利用反射获取注解信息(在反射部分涉及)
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