Sharing examples of using clone() in Java

This article mainly introduces the relevant information about the use of clone() in java. I hope this article can help everyone master the cloning method of clone(). Friends in need can refer to it

How to use clone() in java

Preface:

Clone is copying. In Java language, the clone method is called by the object, so it will be copied. object. To copy an object, you must first allocate a space of the same size as the source object and create a new object in this space. So in the java language, there are:

1 Use the new operator to create an object

2 Use the clone method to copy an object

So what are the similarities and differences between these two methods? The original intention of the new operator is to allocate memory. When the program executes the new operator, it first looks at the type behind the new operator, because only by knowing the type can we know how much memory space to allocate. After allocating the memory, call the constructor to fill in each field of the object. This step is called object initialization. After the constructor returns, an object is created and its reference (address) can be published to the outside, where it can be used. This reference manipulates the object. The first step of clone is similar to new. It allocates memory. When the clone method is called, the allocated memory is the same as the source object (that is, the object that calls the clone method), and then the corresponding fields in the original object are used to fill in the After the field of the new object is filled, the clone method returns, a new and identical object is created, and the reference of this new object can also be published to the outside.

package test; 
 
public class Cloneoo { 
public static void main(String[] args) { 
  test t=new test(); 
  t.changeInt(); 
  System.out.println(t); 
  try { 
    test t1=(test) t.clone();//创建 
    System.out.println(t1); 
    System.out.println(t1.getI()); 
  } catch (CloneNotSupportedException e) { 
    // TODO Auto-generated catch block 
    e.printStackTrace(); 
  } 
   
} 
} 
class test implements Cloneable{ 
  private int i=0; 
  public void setI(int i) { 
    this.i = i; 
  } 
  public int getI() { 
    return i; 
  } 
  public void changeInt(){ 
    this.i=1; 
  } 
  @Override 
  protected Object clone() throws CloneNotSupportedException { 
    // TODO Auto-generated method stub 
    test t=null; 
    t=(test) super.clone(); 
    return t; 
  } 
   
}

test.test@15db9742 
test.test@6d06d69c
1

When the class contains some objects, we need to deep copy, which is copying the objects After that, the clone method is also called to complete the deep copy of the non-basic type attributes in the object.

The clone method performs a shallow copy

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