javase annotation

Student.java

package com.itheima.annotation;@DemoAnno(name="zhangsan")public class Student {}

DemoAnno.java

package com.itheima.annotation;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Retention(RetentionPolicy.RUNTIME)@Target(ElementType.TYPE)public @interface DemoAnno {public String name();public int age() default 100;}

Demo.java

package com.itheima.annotation;public class Demo {public static void main(String[] args) {Class sc = Student.class;if(sc.isAnnotationPresent(DemoAnno.class)){DemoAnno da = (DemoAnno) sc.getAnnotation(DemoAnno.class);String name = da.name();int age = da.age();System.out.println(name+":"+age);}else{System.out.println("no anno");}}}