Problems using getKeyCode ()

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Problems using getKeyCode ()

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#1 by (2 votes)

1

I'm starting to schedule events in java and I have a problem with getKeyCode (). In a JFrame of my program I added this.addKeyListener(lamina1); (lamina1 is an instance of a class that inherits from JPanel) this is the listener code:

public void keyTyped(KeyEvent e) {

    if(e.getKeyCode()==KeyEvent.VK_ENTER){
        chars.add(numcaracteres, true);
    }else{
        char txt=e.getKeyChar();
        chars.add(numcaracteres, txt);
    }

    numcaracteres++;

    repaint();

}

(chars is an instance of ArrayList) The problem I have is that if(e.getKeyCode()==KeyEvent.VK_ENTER) does not work, because when I press enter, it does not execute the code inside the if, I tried to change VK_ENTER for other values to check if it was only with enter, but the same thing happens with any other value

java eventos

asked by Alejandro Arevalo 07.04.2017 в 02:52

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1 answer

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score 2 · Accepted Answer

Use KeyBindings . KeyListener has 2 major deficiencies.

a) You hear all the keys
b) You have to have focus on the component and also that component has to be focusable.

In contrast to KeyBindings, it is binded by a key and you do not necessarily have to be in focus.

A simple example:

AbstractAction enterAction = new AbstractAction() {
    @Override
    public void actionPerformed(ActionEvent e) {
         //code here example
         ((JComponent)e.getSource()).setVisible(Boolean.FALSE);
    }};
 String key = "ENTER";
 KeyStroke keyStroke = KeyStroke.getKeyStroke(key);
 component.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW).put(keyStroke, key);
 component.getActionMap().put(key, enterAction);

You can use these JComponent constants

WHEN_ANCESTOR_OF_FOCUSED_COMPONENT 
WHEN_FOCUSED 
WHEN_IN_FOCUSED_WINDOW