please explain me parameter passing

[pias Khan]

please explain me parameter passingfor the example below:

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.print( v.i );
}
public void another(ValHold v, int i){
i=0;
v.i = 20;
ValHold vh = new ValHold();
v = vh;
System.out.print(v.i);
System.out.print(i);
}
}

[Mattias Arthursson]

When you call the another() method you are passing a copy of your reference to the original object, rather than the actual reference variable. Thus, when you do v=vh in your method you are only pointing the local method variable (declared in the method signature) to point to the new object.

Compare this with the following code:

class Test{
  void doStuff(int local){
    local = 20;
    System.out.println(local);
  }
  
  public static void main(String[] argv){
    Test t = new Test();
    int i = 10;
    t.doStuff(i);
    System.out.println(i);
  }
}  

Again, the parameter will be a copy of the int passed to the method, rather than the actual int variable, so the value of the variable in main() will not be changed.