Kind of transaction in Java SE

Question

Is there any way to create kind of transactions using only Java SE? For example, we have some class with main and an input method. What we do is putting in console some numbers, adding'em to a list and then return this list. But, if user doesn't put any number in console for a 5 sec - program clears out our list, returns this empty list and stops.

And dummy code for example:

public class SomeClass {
    public static void main(String[] args) {
        inputNumbers().forEach(System.out::println);
    }

    public List<String> inputNumbers() {
        Scanner scanner = new Scanner(System.in);
        List<String> result = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            result.add(scanner.nextLine());

            //if nothing happen within 5 sec
            //result.clear();
            //return out empty result;    
        }

        return result;
    }
}

@MichałZiober This possible duplicate also has a possible duplicate... — Twometer, Jan 29 '19 at 17:52
Yes, "duplication" is a common thing. I pointed it out just to increase chance this question will be properly answered. — Michał Ziober, Jan 29 '19 at 18:30

score 1 · Accepted Answer · answered Jan 29 '19 at 17:40

1

Take a look into the Java TimerTask class documentation. There are provided methods for executing such things on a schedule.

answered Jan 29 '19 at 17:40

Dustin

693
8
20

vmaroli · Answer 2 · 2019-01-29T18:09:23.200

Here is one option using Timer task and AWT Robot.

public class SomeClass {

    private volatile boolean exitFlag = false;

    public static void main(String[] args) {
        new SomeClass().inputNumbers().forEach(System.out::println);
    }

    public List<String> inputNumbers() {
        Scanner scanner = new Scanner(System.in);
        List<String> result = new ArrayList<>();
        Timer t = setTimer(5000);
        for (int i = 0; i < 10; i++) {
            result.add(scanner.nextLine());
            if(exitFlag) {
                break;
            }
        }
        scanner.close();
        t.cancel();
        return result;
    }

    private Timer setTimer(int delay) {
        Timer t = new Timer();
        t.schedule( 
                new java.util.TimerTask() {
                    @Override
                    public void run() {
                        Robot robot;
                        try {
                            robot = new Robot();
                            robot.keyPress(KeyEvent.VK_ENTER);
                            exitFlag = true;
                        } catch (AWTException e) {
                            e.printStackTrace();
                        }

                    }
                }, 
                delay 
        );
        return t;
    }
}

I don't think you should rely on a virtual keypress for that matter. — Twometer, Jan 29 '19 at 17:51

Kind of transaction in Java SE

2 Answers2