How do I kick out of a running program?

Question

How do I assign a variable to the ESC. key so that when it is pressed the program is shutdown? I am doing a calculator and the only way that I have seen is doing it directly like:

Scanner console = new Scanner(System.in); 
int x = 1;
while(x==1)
{...
System.out.println("Enter in -1 to exit program");
x = nextInt();
}

I don't know if it is possible to assign, per say a -1 to the escape key. Let me know if you have any ideas? It would be astronomically appreciated. ;-) ... :-)

and all of the necessary imports have been made, just to get that out of the way... — Snare_Dragon, Jun 04 '17 at 18:30
That was it, thanks @baao my astronomical thanks goes to you!! Even though you don't get a physical trophy, and there is no use to this post thanks. :_-) — Snare_Dragon, Jun 04 '17 at 18:57

Andrew Tobilko · Accepted Answer · 2017-06-04T18:49:40.103

2

Unfortunately, you can't.

ESC can't be read by the Scanner. You are supposed to use a key listener by a UI library (for instance, Swing). Have a look at "How to write a key listener?".

In this case, you should ask for a number from a user which is a key of the loop break (like you actually did).

edited Jun 04 '17 at 18:49

answered Jun 04 '17 at 18:45

Andrew Tobilko

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Youcef LAIDANI · Answer 2 · 2017-06-04T18:50:18.993

1

It's a long time when i used a good library, so if you can use JNativeHook library you can easily solve this problem.

Here is an example :

import org.jnativehook.GlobalScreen;
import org.jnativehook.NativeHookException;
import org.jnativehook.keyboard.NativeKeyEvent;
import org.jnativehook.keyboard.NativeKeyListener;

public class TestEscKey implements NativeKeyListener{

    @Override
    public void nativeKeyPressed(NativeKeyEvent nke) {
        if(NativeKeyEvent.getKeyText(nke.getKeyCode()).equals("Echap")){
            System.out.println("I will exit!");
            System.exit(0);
        }else{
           //do another thing
        }
    }

    @Override
    public void nativeKeyReleased(NativeKeyEvent nke) {
    }

    @Override
    public void nativeKeyTyped(NativeKeyEvent nke) {
    }

    public static void main(String[] args) throws NativeHookException {
        try {

            GlobalScreen.registerNativeHook();
        } catch (NativeHookException ex) {
            System.out.println("There was a problem registering the native hook.\n" 
                                + ex.getMessage());
            System.exit(1);
        }
        GlobalScreen.getInstance().addNativeKeyListener(new TestEscKey());
    }
}

edited Jun 04 '17 at 18:50

answered Jun 04 '17 at 18:43

Youcef LAIDANI

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what @S.Nary... ? – Youcef LAIDANI Jun 04 '17 at 18:53
What does the 1st override do through the 2nd override, this is all new to me? – Snare_Dragon Jun 04 '17 at 18:56
this is implementation of the methods in the interface `NativeKeyListener` so you have to download the jar, and then use it in your project like any jar or dependencies yes it is new but it do the trick if you can use it correctly @S.Nary – Youcef LAIDANI Jun 04 '17 at 18:58
Alright thanks, I'll give it a try, @YCF_L. – Snare_Dragon Jun 04 '17 at 18:59
Hey, do these packages work with BlueJ? – Snare_Dragon Jun 04 '17 at 21:24

How do I kick out of a running program?

2 Answers2