Key Detection

[dilpreet28]

Hey

i wrote a keylistener class

public class Keys implements KeyListener {

public static void main(String[] args) {
}

public void keyPressed(KeyEvent e) {
System.out.println("FUNC RUNS");
if (e.getKeyCode() == KeyEvent.VK_NUMPAD1){
System.out.println("1");
}
}

public void keyReleased(KeyEvent e) {
}

public void keyTyped(KeyEvent e) {
}
}

but when i press a key 1 on the numpad it doesn't print out anything, i am making a calculator app, any idea?

[tyroceur]

Is this your whole program?
You haven't associated the keylistner to any component here.

[dilpreet28]

no that's just a class i made for the keylisteners. How do i associate a keyListener with a button?

[tyroceur]

if the button is in this class, then write....

button1.addKeyListener(this);

where button1 is the button name

[dilpreet28]

i have around 15 buttons and they are all in the main class (not this class), how would i reference each button with each key and also when the key is pressed make the same function run as assigned to the button?

[tyroceur]

you can make an instance of this class in your main class and then add Keylisteners to all the buttons.....

or you can totally scrape this class and implement the keylistener to the main class itself like this

public class MainClass {
  public static void main(String args[]) throws Exception {

    JButton[] but=new JButton[15];
    for(int i=0;i<15;i++){
        but[i]=new JButton();
    }
    
// KeyListener
    KeyListener keyListener = new KeyListener() {
      public void keyPressed(KeyEvent keyEvent) {
        printIt("Pressed", keyEvent);
      }

      public void keyReleased(KeyEvent keyEvent) {
        printIt("Released", keyEvent);
      }

      public void keyTyped(KeyEvent keyEvent) {
        printIt("Typed", keyEvent);
      }

      private void printIt(String title, KeyEvent keyEvent) {
        int keyCode = keyEvent.getKeyCode();
        String keyText = KeyEvent.getKeyText(keyCode);
        System.out.println(title + " : " + keyText + " / " + keyEvent.getKeyChar());
      }
    };

    for(int i=0;i<but.length;i++){
         but[i].addKeyListener(keyListener);
    }   
  }
}

Either you can do this and write each associated keys to perform the function of the specified button

Or, you can implement keyBindings using InputMap for this..... These tutorials might help you :
InputMap (Java Platform SE 6)
How to Use Key Bindings (The Java™ Tutorials > Creating a GUI With JFC/Swing > Using Other Swing Features)

Hope that helps.

[tintin]

Hey

i wrote a keylistener class

public class Keys implements KeyListener {

    public static void main(String[] args) {
    }

    public void keyPressed(KeyEvent e) {
        System.out.println("FUNC RUNS");
        if (e.getKeyCode() == KeyEvent.VK_NUMPAD1){
            System.out.println("1");
        }
    }

    public void keyReleased(KeyEvent e) {
    }

    public void keyTyped(KeyEvent e) {
    }
}

but when i press a key 1 on the numpad it doesn't print out anything, i am making a calculator app, any idea?

It is easy... Do like this

button.addKeyListener(new Keys());

Don't forget to +1 my REP

Good luck :)

[Norm]

public void keyReleased(KeyEvent e) {
}

public void keyTyped(KeyEvent e) {
}

Why not have all the methods use println() to see what is happening?

[Lil_Aziz1]

Wouldn't it make more sense to implement the KeyListener to a textfield instead of a button since buttons can't type?

[Norm]

The component receiving key strokes has to have the focus? Read the KeyEvent doc.

[Lil_Aziz1]

So clicking a button releases a KeyListener action?

[Norm]

releases a KeyListener action

Sends a KeyEvent