CODEWITHSUNDEEP
javacopy
Leszek
Leszek

Reputation: 1231

Deep copy of abstract object

Java here. I've got the following situation:

abstract class A { /*...*/ };
class Derived1 extends A { /*...*/ };
class Derived2 extends A { /*...*/ };
class Derived3 extends A { /*...*/ };

and elsewhere in the code someone sends me objects of type 'A':

A obj1 = getObject();

now I'd like to do a deep copy of object 'obj1', something like

A obj2 = obj1.deepCopy();

but I don't know how to implement this. I don't know the type of obj1 (well, it is either Derived1, Derived2 or Derived3).
Is it possible to write a deep copy function once and avoid doing things like

if( obj1 instancef Derived1 ) 
  {
  A obj2 = new Derived1((Derived1)obj1);
  }

and having to implement three copy constructors?

Upvotes: 0

Views: 141

Answers (1)

CodeScale
CodeScale

Reputation: 3314

yes by using a polymorphic deepCopy method.

abstract class A {
    A(A t) {
    }

    A() {}

    public abstract A deepCopy();
}

class D1 extends A {

    D1(D1 t) {
        //copy constructor
    }

    D1() {
        //no-arg constructor
    }

    @Override
    public D1 deepCopy() {                        
        return new D1(this);
    }
}

A a = new D1();
A copy = a.deepCopy(); //the deepCopy is called D1 class

Upvotes: 1

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