【java】对象克隆protected Object clone() throws CloneNotSupportedException

 package 对象克隆;
 class A implements Cloneable{//要具备clone()功能必须要实现Cloneable接口，此接口里无方法，只起标识作用。
     private String value;
     public A(String value){
         this.value=value;
     }
     public void setValue(String value) {
         this.value = value;
     }
     @Override
         public String toString() {
             return "value="+value;
         }
     @Override
     protected Object clone() throws CloneNotSupportedException {
         return super.clone();
     }//因为Object类里的clone方法是protected权限，所以要重写才能在主方法里调用。
 }
 public class Test_clone {
     public static void main(String[] args) {
         A a1=new A("我是A1");
         A a2=null;
         try {
             a2=(A)a1.clone();
         } catch (CloneNotSupportedException e) {
             e.printStackTrace();
         }
         System.out.println(a1);//value=我是A1
         System.out.println(a2);//value=我是A1
         a1.setValue("a1->A1");
         System.out.println(a1);//value=a1->A1
         System.out.println(a2);//value=我是A1
     }
 }