Java - call by reference and call by value

Call by reference

It can be used to pass the instance of the class to the method which can be handled entire class in the method.

example:






import java.awt.Dimension;

public class A {
    public static void main(String[] args)
    {
        A a =new A();
        Dimension d = new Dimension(10,20);
        System.out.println(d.height);
        a.getvalue(d);
        System.out.println(d.height);
    }
   
    void getvalue(Dimension dim)
    {
         dim.height = dim.height+1;
       
    }

}

output:

20
21

• The value which can modified by the method continued the same value in upcoming method also.
• It can replace the original value
• 
  

The example for call by value:



public class B {
   
    public static void main(String[] args)
    {
        int a=5;
        B b =new B();
        System.out.println(a);///output will be 5
       
        b.modify(a); //output will be 6
       
        System.out.println(a); //output will be 5
    }

    void modify(int x)
    {
        x=x+1;
        System.out.println(x);
    }
}

• The value modify can be used in particular method
• Again the original value can be used in the main method.