CODEWITHSUNDEEP
java
user7
user7

Reputation: 525

execution of a statement inside a method

how after the execution of if block in the whole program, the statement "System.out.println("after method showValue\t:"+ab);" is still able to fetch previous values ? i thought this statement will print 0 everytime but its not happening ?

public class Me{

public static void main(String[] args) {
    int ab=98;
    System.out.println(" value of ab in main at start\t:"+ab);
    Mno ref=new Mno();
    ref.showValue(ab);
    System.out.println("value of ab in Main After completion\t:"+ab);
}
}

class Mno{
    void showValue(int ab){
    System.out.println("Before method showvalue\t:"+ab);
    if (ab!=0){
        showValue(ab/10);}
    System.out.println("after method showValue\t:"+ab);

}

}

Upvotes: 0

Views: 269

Answers (1)

arshajii
arshajii

Reputation: 129547

Java is pass-by-value, so in showValue() you're not handling the ab you have declared in your main() but rather dealing with a copy. Come to think of it, you're not even reassigning ab anywhere, so how could it possibly change?

In any case, you can see the pass-by-value concept at work in something like this:

public static void main(String[] args) {
    int n = 42;
    foo(n);
    System.out.println(n);
}

public static void foo(int n) {
    n = 0;
}

42

In foo(), we are reassigning a copy of n, not changing the n defined in main().

EDIT I see now that you're asking why the second print statement in showValue() doesn't print 0 each time it is reached. To see why, let's step through the function call by hand. This is what happens when you call that showValue(ab) in main():

  • Call function with argument of ab = 98.
  • Print 98 (1st print statement)
  • 98 != 0, so: (if-statement)
    • Call function again with argument of ab = ab/10 == 9.
    • Print 9 (1st print statement)
    • 9 != 0, so: (if-statement)
      • Call function again with argument of ab = ab/10 == 0.
      • Print 0 (1st print statement)
      • 0 == 0, so don't enter if-statement.
      • Print 0 (2nd print statement)
    • Print ab, which is 9 here. (2nd print statement)
  • Print ab, which is 98 here. (2nd print statement)

Upvotes: 3

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