Java Swing Tutorial - Java KeyEvent KEY_RELEASED

• Back to KeyEvent  ↑

Syntax

KeyEvent.KEY_RELEASED has the following syntax.

public static final int KEY_RELEASED

Example

In the following code shows how to use KeyEvent.KEY_RELEASED field.

/*w w  w .  j a va2s.  c  om*/
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;

public class Main extends JFrame implements KeyListener, ActionListener {
  JTextArea displayArea;
  JTextField typingArea;
  static final String newline = System.getProperty("line.separator");

  public static void main(String[] args) {
    Main frame = new Main();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    frame.addComponentsToPane();

    frame.pack();
    frame.setVisible(true);
  }
  private void addComponentsToPane() {

    JButton button = new JButton("Clear");
    button.addActionListener(this);

    typingArea = new JTextField(20);
    typingArea.addKeyListener(this);

    displayArea = new JTextArea();
    displayArea.setEditable(false);
    JScrollPane scrollPane = new JScrollPane(displayArea);
    scrollPane.setPreferredSize(new Dimension(375, 125));

    getContentPane().add(typingArea, BorderLayout.PAGE_START);
    getContentPane().add(scrollPane, BorderLayout.CENTER);
    getContentPane().add(button, BorderLayout.PAGE_END);
  }


  /** Handle the key typed event from the text field. */
  public void keyTyped(KeyEvent e) {
    displayInfo(e, "KEY TYPED: ");
  }

  /** Handle the key pressed event from the text field. */
  public void keyPressed(KeyEvent e) {
    displayInfo(e, "KEY PRESSED: ");
  }

  /** Handle the key released event from the text field. */
  public void keyReleased(KeyEvent e) {
    displayInfo(e, "KEY RELEASED: ");
  }

  /** Handle the button click. */
  public void actionPerformed(ActionEvent e) {
    // Clear the text components.
    displayArea.setText("");
    typingArea.setText("");

    // Return the focus to the typing area.
    typingArea.requestFocusInWindow();
  }
  private void displayInfo(KeyEvent e, String keyStatus) {
    int id = e.getID();
    String keyString;
    if (id == KeyEvent.KEY_RELEASED) {
      char c = e.getKeyChar();
      keyString = "key character = '" + c + "'";
    } else {
      int keyCode = e.getKeyCode();
      keyString = "key code = " + keyCode + " (" + KeyEvent.getKeyText(keyCode)
          + ")";
    }

    int modifiersEx = e.getModifiersEx();
    String modString = "extended modifiers = " + modifiersEx;
    String tmpString = KeyEvent.getModifiersExText(modifiersEx);
    if (tmpString.length() > 0) {
      modString += " (" + tmpString + ")";
    } else {
      modString += " (no extended modifiers)";
    }

    String actionString = "action key? ";
    if (e.isActionKey()) {
      actionString += "YES";
    } else {
      actionString += "NO";
    }

    String locationString = "key location: ";
    int location = e.getKeyLocation();
    if (location == KeyEvent.KEY_LOCATION_STANDARD) {
      locationString += "standard";
    } else if (location == KeyEvent.KEY_LOCATION_LEFT) {
      locationString += "left";
    } else if (location == KeyEvent.KEY_LOCATION_RIGHT) {
      locationString += "right";
    } else if (location == KeyEvent.KEY_LOCATION_NUMPAD) {
      locationString += "numpad";
    } else { // (location == KeyEvent.KEY_LOCATION_UNKNOWN)
      locationString += "unknown";
    }

    displayArea.append(keyStatus + newline + "    " + keyString + newline
        + "    " + modString + newline + "    " + actionString + newline
        + "    " + locationString + newline);
    displayArea.setCaretPosition(displayArea.getDocument().getLength());
  }
}

• Back to KeyEvent  ↑