Exam on 9th july -- pl help

[padmini Babu]

Acc to me the ans to this question is 20,0,30 . any comments??
Question 51) � NU
Given the following code what will be the output?
class ValHold{
public int i = 10;
}
public class ObParm{
public static void main(String argv[]){
ObParm o = new ObParm();
o.amethod();
}
public void amethod(){
int i = 99;
ValHold v = new ValHold();
v.i=30;
another(v,i);
System.out.println(v.i);
}//End of amethod
public void another(ValHold v, int i){
i=0;
v.i = 20;
ValHold vh = new ValHold();
v = vh;
System.out.println(v.i+ " "+i);
}//End of another
}
1) 10,0, 30
2) 20,0,30
3) 20,99,30
4) 10,0,20 �C
Answer to Question 51)
Answer 51)
Objective 5.4)
4) 10,0,20
In the call
another(v,i);
A reference to v is passed and thus any changes will be intact after this call.
Thanks in advance
Padmini

[Vanitha Sugumaran]

Hi Padmini,
See the comments.

class ValHold{
public int i = 10;
}
public class ObParm{
public static void main(String argv[]){
ObParm o = new ObParm();
o.amethod();
}
public void amethod(){
int i = 99;  // this is a local variable i --> 99
ValHold v = new ValHold();
v.i=30; // now the value the i of v --> 30 (1)
another(v,i);
System.out.println(v.i); 
//the value of v.i is changed to 20 in another() so it will be print 20 here.
}//End of amethod
public void another(ValHold v, int i){
i=0;
v.i = 20; // ---> here the value of i v is again changed to 
ValHold vh = new ValHold();
v = vh; //--> here you are changing the reference. so now v.i is 10
System.out.println(v.i+ " "+i); // v.i is 10,  and local variable i is 0
}//End of another
}

Hope this helps,
Vanitha.

[Chuck Lorenz]

Vanitha,
In another(), your comments say that assigning vh to v means v.i == 10 because it references a new Valhold object. Yet back in amethod(), your comments say the System.out.println(v.i) will print "20" due to the changes made in another(). Does not the reference to the new ValHold object supplant the change to 20, so that System.out.println(v.i) should print "10"?
Thanks,
Chuck

[Vanitha Sugumaran]

Hi,
Changing the reference of v in another() does not affect the state of the original object referenced by v.
I had the same confusion, ranchers have cleared my doubt.
Take a look at this sample code,

public class RefCheck
{
String msg = "Red";
public static void changeRef(RefCheck rc)
{
System.out.println("Before changing reference " + rc.msg + " rc is " + rc);
//Before changing reference Red rc is RefCheck@70192c30
rc.msg = "Green";
System.out.println("After changing the value of the msg " + rc.msg + " rc is " + rc);
//After changing the value of the msg Green rc is RefCheck@70192c30
rc = new RefCheck();

System.out.println("After changing Reference to new object " + rc.msg + " rc is " + rc);
//After changing Reference to new object Red rc is RefCheck@72952c30

}
public static void main(String args[])
{
RefCheck ref = new RefCheck();
System.out.println("Before changeRef " + ref.msg + " ref is " + ref);
//Before changeRef Red ref is RefCheck@70192c30
changeRef(ref);
System.out.println("After changeRef " + ref.msg + " ref is " + ref);
//prints After changeRef Green ref is RefCheck@70192c30

}
}

Hope this helps,
Vanitha.

[This message has been edited by Vanitha Sugumaran (edited July 07, 2001).]

[Snylt Master]

Thanks for clearing out the oParm , valhold code.

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