Method parameters doubt?

[Joe San]

Hi Guys,

Consider the code below,

class GFC304 {
  static void m1(int[] i1, int[] i2) {
    int[] i3 = i1; i1 = i2; i2 = i3;
  }
  public static void main (String[] args) {
    int[] i1 = {1}, i2 = {3}; m1(i1, i2);
    System.out.print(i1[0] + "," + i2[0]);
}}

The above code prints 1, 3

And the code below,

class GFC305 {
  static void m1(int[] i1, int[] i2) {
    int i = i1[0]; i1[0] = i2[0]; i2[0] = i;
  }
  public static void main (String[] args) {
    int[] i1 = {1}, i2 = {3}; m1(i1, i2);
    System.out.print(i1[0] + "," + i2[0]);
}}

prints 3, 1

Can you guys please explain this?

Thanks in advance.

[Keith Lynn]

Originally posted by Jothi Shankar Kumar Sankararaj:
Hi Guys,

Consider the code below,

class GFC304 {
  static void m1(int[] i1, int[] i2) {
    int[] i3 = i1; i1 = i2; i2 = i3;
  }
  public static void main (String[] args) {
    int[] i1 = {1}, i2 = {3}; m1(i1, i2);
    System.out.print(i1[0] + "," + i2[0]);
}}

The above code prints 1, 3

And the code below,

class GFC305 {
  static void m1(int[] i1, int[] i2) {
    int i = i1[0]; i1[0] = i2[0]; i2[0] = i;
  }
  public static void main (String[] args) {
    int[] i1 = {1}, i2 = {3}; m1(i1, i2);
    System.out.print(i1[0] + "," + i2[0]);
}}

prints 3, 1

Can you guys please explain this?

Thanks in advance.

Notice in the first code that there is nothing within the method that has any effect on the array references sent to it.

In the second code, the elements of the arrays are actually swapped.

[Joe San]

I got the answer, arrays are passes by reference values.

Thanks keith.

[Keith Lynn]

No, all parameters are sent by value.

When you use an array reference (or any other reference) as a parameter to a method, what gets sent to the method is a copy of the reference.

So that means when a method begins executing, the formal parameters of the method point to the same objects that the actual parameters do.

However, if you change where the formal parameter points, that does not change anything about where the actual parameter points.
[ December 06, 2006: Message edited by: Keith Lynn ]

[Harish Paravasthu]

Hello Frenz..

Am also confused that java is pass by reference but its not...it is by PASS BY VALUE

Explanation:

when we pass parameters to a method...we are actually passing the "COPY OF REFERENCE VALUE i.e in bits"
so whatever the variable we are just passing the size(in bits) of that type.

Harish..