class ReferencePreservation { public static void main(String[] args) { B b = new B(); b.x = 10; System.out.println("Before method call b.x " + b.x); A a = new A(); a.method(b); System.out.println("After method call b.x " + b.x); } } class B { int x; } class A { public void method(B obj) { System.out.println("Inside method call before modification obj.x " + obj.x); obj.x = 300; System.out.println("Inside method call before modification obj.x " + obj.x); obj = null; System.out.println("After putting null obj " + obj); } }