Question

In class B, how can I create an object of class A other than the process of object creation (i.e. without creating an object having null)?

class A
  {
    public int one;  
   A(A a)
    {
      a.one=1;
    }
  }
class B
  {
   public static void main(String...args)
     {
     //now how to create an object of class A over here.
     }
  }

Answer 1

You cannot normally do this in Java.

However, it’s possible with heavy cheating. Don’t do this in production code. But for the sake of argument:

1) With Mockito (But won’t work with a security manager):

import org.mockito.Mockito;

class B {

    public static void main(String... args) {
        A mockedA = Mockito.mock(A.class);
        A realA = new A(mockedA);
        System.out.println(realA);
    }
}

2) Here’s another way to do it overriding finalize().