Question

1. This question is related to making an object method call by reference instead of by value. Use the (CallValueTest.java). Convert the calculation method (calc(..) ) in the Test class. You need to modify the Test class attributes and constructor to support this new cal (…) method. Your program should display:

Before call obj.a 15 obj.b is 20

Before call obj.a 30 obj.b is 10

CallValueTest.java

package com.Assignment3.Q1;

class Test {
  
   void calc(int a, int b) {
       a *= 2;
       b /= 2;
       System.out.println(" in calc a = " + a + " b = " + b);
   }
  
}
public class CallByValueTest {
   public static void main (String args[]) {
       Test ob = new Test();
       int a =15, b = 20;
       System.out.println ("Before calc :a = " + a + " b " + b);
      
       ob.calc (a, b );
      
       System.out.println(" After calc: a = " + a + " b " + b);
      
   }
}

Answer 1

//Java code

package com.Assignment3.Q1;

/**
 * Since in call by value, We are passing primitive type(int, char..) Which supports pass by value.
 * To convert the it into call by reference, We need to wrap them into reference type (Object).
 */
class Test {
    //attributes 
    int a,b;

    void calc() {
        a *= 2;
        b /= 2;
        System.out.println(" in calc a = " + a + " b = " + b);
    }

}
public class CallByRefTest {
    public static void main (String args[]) {

        Test ob = new Test();
            ob.a=15;
            ob.b =20;
        System.out.println ("Before calc :a = " + ob.a + " b " + ob.b);
        ob.calc ( );

        System.out.println(" After calc: a = " + ob.a + " b " + ob.b);

    }
}

//output

//If you need any help regarding this solution ......... please leave a comment ...... thanks