passing object references

[srikanth reddy]

can anybody explain the o/p???its a bit confusing ???

class Value
{
public int i = 15;
}
class Test
{
public static void main(String argv[])
{
Test t = new Test();
t.first();
}
public void first()
{
int i = 5;
Value v = new Value();
v.i = 25;
second(v, i);
System.out.println(v.i);
}
public void second(Value v, int i)
{
i = 0;
v.i = 20;
Value val = new Value();
v = val;
System.out.println(v.i + " " + i);
}

}

thanks
srikanth

[Dharmesh Gangani]

Srikanth,
Is there any specific part of the code you are not able to understand OR you are facing problem with the entire code.

[Prashanth Raghavan]

I guess the output will be 15 0 and 20.
[ August 11, 2005: Message edited by: Prashanth Raghavan ]

[Marcelo Ortega]

I haven�t compiled it but the answer should be:

15 1

The method public void second(Value v, int i) takes a COPY of a reference and a COPY of an integer literal.

Don�t be fooled by this (in the second method):

i = 0;      //local variable reasignment
v.i = 20;   //changes the state of OBJECT refered to by v (i)
Value val = new Value();
 
v = val;    //v now referes to val (aliases)
System.out.println(v.i + " " + i);
 

[Marcelo Ortega]

sorry i ment 15 0

[srikanth reddy]

i answer while compiling comes out to b 15 0 20

i didnt get from Value val = new Value();
v = val;

what happens exactly???

thanks & regards

srikanth

[srikanth reddy]

i answer while compiling comes out to b 15 0 20

i didnt get from Value val = new Value();
v = val;

what happens exactly???

thanks & regards

srikanth

[Marcelo Ortega]

  
class Value
{
public int i = 15;
}
class Test
{
public static void main(String argv[])
{
Test t = new Test();
t.first();
}
public void first()
{
int i = 5;
Value v = new Value();
v.i = 25;
second(v, i);
System.out.println(v.i);     //1
}
public void second(Value v, int i)
{
i = 0;
v.i = 20;    //2
Value val = new Value();
v = val;
System.out.println(v.i + " " + i);
}
 
}
 

look at the line commented with 2, here you are changing the value of the object which v refers to at the time (the one passed in the variable list). Then, v gets reasigned. When the method returns, 20 will be printed because the variable v in the second method (at 2) changed it before it got reasigned.

hope i explained myself properly.