java - HashMap 中克隆方法的输出

Question

     // Creating a new HashMap
     HashMap<Integer, String> hmap2 = new HashMap<Integer, String>(); 

     // cloning first HashMap in the second one
     hmap2=(HashMap)hmap.clone();
     //System.out.println("Cloned Map contains: "+hmap2); 
     String x = hmap.get(11);
     x = "aks";
     hmap.put(11, x);
     hmap.put(99, "kdkshkjshdk");

     System.out.println("Cloned Map contains: "+hmap); 
     System.out.println("Cloned Map contains: "+hmap2); 
  } 
}

为什么 hmap 中的更改没有反射(reflect)在 hmap2 中？这是一个浅拷贝，hmap 和 hmap2 都指向相同的内存引用。有错误的地方请指正。

Answer 1

您正在将空 hmap 克隆到 hmap2，然后将值设置到 hmap。

     // Creating a new HashMap

     HashMap<Integer, String> hmap = new HashMap<Integer, String>();

     HashMap<Integer, String> hmap2 = new HashMap<Integer, String>();

   //System.out.println("Cloned Map contains: "+hmap2); 

     String x = hmap.get(11);

     x = "aks";

     hmap.put(11, x);

     hmap.put(99, "kdkshkjshdk");

     // cloning first HashMap in the second one

     hmap2=(HashMap)hmap.clone();



     System.out.println("Cloned Map contains: "+hmap); 
     System.out.println("Cloned Map contains: "+hmap2);