Final

[Sathya Shanmugam]

hi Folks,

Could anyone please explain how the result is " true true "

  
 class Fizz
{
 int x = 5;
 public static void main(String[] args)
 {
     final Fizz f1 = new Fizz();
     Fizz f2 = new Fizz();
     Fizz f3 = FizzSwitch(f1,f2);
    System.out.println((f1==f3) +" " +(f1.x == f3.x));
}
static Fizz FizzSwitch(Fizz x, Fizz y)
{
final Fizz z = x;
z.x = 6;
return z;
}}
 
 

[Barry Gaunt]

It gives the same output without the final keywords. So what's this got to do with final?

[Meena R. Krishnan]

AFter the call to FizzSwitch(), both f3 and f1 are the same and both have the same value of 6 which got assigned in the switch method.

FizzSwitch() takes f1 as its first arg, and assigns the value of 6 by temporarily assigning it to z and returns f1.

[swarna dasa]

when you declare an object final then it means that you can not change the reference to another object, but the objects state can be changed.

final Test o = new Test();
o= new Test(); //CANNOT BE DONE
o.x=9; //CAN BE DONE

where
public Test {
int x =0;
}

Also when you pass an argument to the method you pass a COPY OF THE REFERENCE.

so
//main method excerpt
Test a= new Test();
a.x=7;
Test q =method(a); //Now q.x value is 45 and a.x is 45
//if b=null is uncommented then q will be null and a.x will be 45


static Test method (Test a) {
Test b=a;
b.x=45;
//b=null;
return b;
}


Hope this gives you a headstart