How to use KeyStroke class?

**Truster** · 12-02-2010

Hi friend,

I have lots of queried regarding the classes of java programming language. One of them is 'KeyStroke class'. I am unable to understand the concept of 'KeyStroke class'. Even I don't know where to make use of 'KeyStroke class'. I have referred many advanced java book, but nothing was helpful. If you have knowledge about the 'KeyStroke class', then please let me aware about the same. Your help would be greatly appreciated.

**Modifier** · 12-02-2010

Hi,

A KeyStroke class represents a key action on the keyboard, or equivalent input device. KeyStrokes can correspond to only a press or release of a particular key, just as KEY_PRESSED and KEY_RELEASED KeyEvents do; alternately, they can correspond to typing a specific Java character, just as KEY_TYPED KeyEvents do. In all cases, KeyStrokes can specify modifiers (alt, shift, control, meta, or a combination thereof) which must be present during the action for an exact match.

**Praetor** · 12-02-2010

Hi friend, Pleas refer below example of 'KeyStroke class'. Which will show you the use of KeyStroke class methods:

Code:

import javax.swing.KeyStroke;

public class KeyTesterDemo {
  static class MyActionListener extends AbstractAction {
    MyActionListener(String s) {
      super(s);
    }

    public void actionPerformed(ActionEvent e) {
      System.out.println(getValue(Action.NAME));
    }
  }

  public static void main(String args[]) {
    String actionKey = "theAction";
    JFrame ft = new JFrame("Key Tester");
    JButton jb1 = new JButton("<html><center>B<br>Focused/Typed");
    Container panet = f.getContentPane();
    panet.add(jb1, BorderLayout.NORTH);
  
    stroke = KeyStroke.getKeyStroke("ctrl C");
    action = new MyActionListener("Action Didn't Happen");
    inputMap = jb2.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
    inputMap1.put(stroke, actionKey);
    actionMap1 = jb2.getActionMap();
    actionMap1.put(actionKey, action);

    ft.setSize(400, 200);
    ft.show();
  }
}

**Katty** · 12-02-2010

Following are the methods of KeyStroke class, these methods have same name but with different parameters:

getKeyStrokeForEvent(KeyEvent anEvt)
getKeyStroke(String st)
getKeyStroke(int keyCde, int modfr, boolean onKeyRelease)
getKeyStroke(char keyChr, boolean onKeyRelease)
getKeyStroke(Character keyChr, int modfr)

**kelfro** · 12-02-2010

Below is the some part of java code. In this code I used the class 'KeyStroke' to find out the key pressed by user. I suggest you to study following code:

Code:

public static void main(String args[]) {
    String actionKey = "theAction";
    JFrame fv = new JFrame("Key Tester");
    JButton jb01 = new JButton("<html><center>B<br>Focused/Typed");
    JButton jb02 = new JButton("<html><center>Ctrl-C<br>Window/Pressed");
    JButton jb03 = new JButton("<html><center>Shift-D<br>Ancestor/Released");
    Container pane = f.getContentPane();
    pane.add(jb01, BorderLayout.NORTH);
    
    KeyStroke stroke = KeyStroke.getKeyStroke("typed G");
    
    Action action = new MyActionListener("Action Happened");
    inputMap.put(stroke, actionKey);
    ActionMap actionMap = jb01.getActionMap();
    actionMap.put(actionKey, action);
    fv.setSize(300, 200);
    fv.show();
  }