How do I copy an object in Java?

Question

Consider the code below:

DummyBean dum = new DummyBean();
dum.setDummy(\"foo\");
System.out.println(dum.getDummy()); // prints \'foo\'

DummyBean dumtwo = du         


        

Answer 1

class DB {
  private String dummy;

  public DB(DB one) {
    this.dummy = one.dummy; 
  }
}

Answer 2

You can try to implement Cloneable and use the clone() method; however, if you use the clone method you should - by standard - ALWAYS override Object's public Object clone() method.

Answer 3

Yes. You need to Deep Copy your object.

Answer 4

To do that you have to clone the object in some way. Although Java has a cloning mechanism, don't use it if you don't have to. Create a copy method that does the copy work for you, and then do:

dumtwo = dum.copy();

Here is some more advice on different techniques for accomplishing a copy.

Answer 5

Deep Cloning is your answer, which requires implementing the Cloneable interface and overriding the clone() method.

public class DummyBean implements Cloneable {

   private String dummy;

   public void setDummy(String dummy) {
      this.dummy = dummy;
   }

   public String getDummy() {
      return dummy;
   }

   @Override
   public Object clone() throws CloneNotSupportedException {
      DummyBean cloned = (DummyBean)super.clone();
      cloned.setDummy(cloned.getDummy());
      // the above is applicable in case of primitive member types like String 
      // however, in case of non primitive types
      // cloned.setNonPrimitiveType(cloned.getNonPrimitiveType().clone());
      return cloned;
   }
}

You will call it like this DummyBean dumtwo = dum.clone();