Java OCA OCP Practice Question 1578

Question

What will be the output when the following program is run? 

public class Main{
    char c;/*from w  w  w.ja v a 2  s.  c o  m*/
    public void m1 (){
        char [] myArray =  {  'a' ,  'b'};
        m2 (c, myArray);
        System.out.println(((int)c)  + ", " + myArray [1] );
    }
    public void m2 (char c, char [] myArray){
        c =  'b';
        myArray [1] = myArray [0] =  'm';
    }
    public static void main (String args []){
        new Main ().m1 ();
    }
}

Select 1 option

  • A. Compile time error.
  • B. , m
  • C. 0 , m
  • D. b , b
  • E. b , m


Correct Option is  : C

Note

Arrays are Objects (i.e. myArray instanceof Object is true) so are effectively passed by reference.

So in m1 () the change in myArray [1] done by m2 () is reflected everywhere the array is used.

c is a primitive type and is passed by value.

In method m2 () the passed parameter c is different than instance variable 'c' as local variable hides the instance variable.

So instance member 'c' keeps its default (i.e. 0) value.




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