I'm receiving a resource leak: 'in' is never closed warning

Question

public class ArrayReversal {
    public static void main(String[] args) {
        double[] numbers = readInputs(5);
        printReversed(numbers);
    }

    public static double[] readInputs(int numberOfInputs) {
        System.out.println("Enter " + numberOfInputs + "numbers: ");
        Scanner in = new Scanner(System.in);
        double[] inputs = new double[numberOfInputs];
        for (int i = 0; i < inputs.length; i++) {
            inputs[i] = in.nextDouble();
        }
        return inputs;
    }

    public static void printReversed(double[] values) {
        for(int i = values.length - 1; i>= 0; i--) {
            System.out.print(values[i] + " ");
        }
    }
    //in.close();
}

i have close() commented because it was giving me a syntax error saying an identifier is expected. So i'm not sure where to put it.

Try moving `in.close()` to the `readInputs` method, where `in` is defined. Put it just before the `return` statement. — Ted Hopp, Nov 01 '16 at 19:47
In this particular case (when `System.in` is used as incoming stream) you do not really need it. — PM 77-1, Nov 01 '16 at 19:48
Related: http://stackoverflow.com/questions/14142853/close-a-scanner-linked-to-system-in — Ted Hopp, Nov 01 '16 at 19:49

FMiscia · Answer 1 · 2016-11-01T19:56:00.493

2

'in' is never closed warning

So close it.

 public static double[] readInputs(int numberOfInputs) {
        System.out.println("Enter " + numberOfInputs + "numbers: ");
        Scanner in = new Scanner(System.in);
        double[] inputs = new double[numberOfInputs];
        for (int i = 0; i < inputs.length; i++) {
            inputs[i] = in.nextDouble();
        }
        //be aware: you are globally closing System.in
        in.close();
        return inputs;
    }

edited Nov 01 '16 at 19:56

answered Nov 01 '16 at 19:52

FMiscia

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Please be aware that this will close `System.in` which is fine as long as you are never going to read from `System.in` again in the application. – CollinD Nov 01 '16 at 19:53

I'm receiving a resource leak: 'in' is never closed warning

1 Answers1