枚举类
自定义枚举类
public class SeasonTest {
public static void main(String[] args) {
Season autumn = Season.AUTUMN;
System.out.println(autumn);
}
}
class Season {
private final String SeasonName;
private final String SeasonDesc;
public Season(String seasonName, String seasonDesc) {
SeasonName = seasonName;
SeasonDesc = seasonDesc;
}
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", "天寒地冻");
public String getSeasonName() {
return SeasonName;
}
public String getSeasonDesc() {
return SeasonDesc;
}
@Override
public String toString() {
return "Season{" +
"SeasonName='" + SeasonName + '\'' +
", SeasonDesc='" + SeasonDesc + '\'' +
'}';
}
}
enum定义枚举类
public class EnumTest {
public static void main(String[] args) {
// 获取所有枚举类的所有对象构成的数组
Season1[] values = Season1.values();
for (int i = 0; i < values.length; i++) {
System.out.println(values[i]);
values[i].show();
}
// 根据字符串返回枚举对象
Season1 spring = Season1.valueOf("SPRING");
System.out.println(spring);
}
}
interface Info {
void show();
}
enum Season1 implements Info {
// 枚举类实现接口的一种方式
SPRING("春天", "春暖花开") {
@Override
public void show() {
}
},
SUMMER("夏天", "夏日炎炎") {
@Override
public void show() {
}
},
AUTUMN("秋天", "秋高气爽") {
@Override
public void show() {
}
},
WINTER("冬天", "天寒地冻") {
@Override
public void show() {
}
};
private final String seasonName;
private final String seasonDesc;
public String getSeasonName() {
return seasonName;
}
public String getSeasonDesc() {
return seasonDesc;
}
Season1(String seasonName, String seasonDesc) {
this.seasonName = seasonName;
this.seasonDesc = seasonDesc;
}
}
注解
自定义注解
public @interface MyAnnotation {
String value() default "hello"; // 默认值 hello
}
@MyAnnotation(value = "hello world")
class MyTest {
}
元注解
JDK8新特性
可重复注解
JDK8以前
public @interface MyAnnotation {
String value() default "hello"; // 默认值 hello
}
public @interface MyAnnotations {
MyAnnotation[] value();
}
@MyAnnotations({@MyAnnotation(value = "a"), @MyAnnotation(value = "b")})
class MyTest {
}
JDK8以后
@Repeatable(MyAnnotations.class)
public @interface MyAnnotation {
String value() default "hello"; // 默认值 hello
}
public @interface MyAnnotations {
MyAnnotation[] value();
}
@MyAnnotation(value = "a")
@MyAnnotation(value = "b")
class MyTest {
}
注意:MyAnnotations 与 MyAnnotation的 Retention、Inherited 和 Target 必须相同