Passing array to a function and using that array in an Enhanced for loop

Question

When I pass the array "bucky" to the change function and in the change function if I use an enhanced for loop, the variable counter gives the error "The value of the local variable counter is not used"

But if I put the body of the for loop in an System.out.println(counter+=5) the error does not appear

class apples{
 public static void main(String[] args) {
  int bucky[]={3,4,5,6,7};

  change(bucky);
  }

  public static void change(int x[]){
    for(int counter: x){
     counter+=5;
    }
  }
}

Why does this code give the error I mentioned above since I'm using the counter variable in the enhanced for loop?

Edit - my objective is to change values of the array inside the "change" function and return it back to main.

Try and print the content of bucky in your main after calling change. You'll see why it thinks counter is not used. — Federico klez Culloca
– Federico klez Culloca, Commented Jul 12, 2022 at 9:36
You're "using" but without effect, counter is just a local variable that'll take thev values or the array one by one, but won't change the array values. It you're printing it then you need the variable, but for now there is on real use of having that variable — azro
– azro, Commented Jul 12, 2022 at 9:40
@ThulithaGurusinghe basically you don't. You use a normal loop. — Federico klez Culloca
– Federico klez Culloca, Commented Jul 12, 2022 at 9:44
I suggest you read Is Java "pass-by-reference" or "pass-by-value"? to have a more informed understanding on what you can and can't do with arrays and reference types more generally. — Federico klez Culloca
– Federico klez Culloca, Commented Jul 12, 2022 at 9:46
@ThulithaGurusinghe , shared answer. please check and confirm — Ashish Patil
– Ashish Patil, Commented Jul 12, 2022 at 10:01

Ashish Patil · Accepted Answer · 2022-07-12 10:01:08Z

2

Question is about updating original array values, then you have to use normal for loop so that each index values can be updated:

class apples{
 public static void main(String[] args) {
  int bucky[]={3,4,5,6,7};

  bucky = change(bucky);
  for(int b:bucky) {
        System.out.println(b);
    }
  }

  public static void change(int x[]){
    for (int i = 0; i < x.length; i++) {
        x[i]=x[i]+5;
    }
    return x;
  }
}

answered Jul 12, 2022 at 10:01

Ashish Patil

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