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swing:buttons

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Buttons, Check Boxes & Radio Buttons

Για την δημιουργία ενός button μπορείτε να χρησιμοποιήσετε μία κλάση από τις απογόνους της κλάσης javax.swing.AbstractButton, όπως οι JButton, JCheckBox ή JRadioButton. Άλλες υποκλάσεις της κλάσης AbstractButton είναι οι JMenuItem, JCheckBoxMenuItem και JRadioButtonMenuItem τις οποίες θα δούμε στη συνέχεια.

Η κλάση JButton

Δείτε, μεταγλωττίστε και τρέξτε το παρακάτω παράδειγμα από το site της Oracle, το οποίο και θα συζητήσουμε στη συνέχεια.

package components;
 
import javax.swing.AbstractButton;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.ImageIcon;
 
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
 
/* 
 * ButtonDemo.java requires the following files:
 *   images/right.gif
 *   images/middle.gif
 *   images/left.gif
 */
public class ButtonDemo extends JPanel
            implements ActionListener {
  protected JButton b1, b2, b3;
 
  public ButtonDemo() {
    ImageIcon leftButtonIcon = createImageIcon("images/right.gif");
    ImageIcon middleButtonIcon = createImageIcon("images/middle.gif");
    ImageIcon rightButtonIcon = createImageIcon("images/left.gif");
 
    b1 = new JButton("Disable middle button", leftButtonIcon);
    b1.setVerticalTextPosition(AbstractButton.CENTER);
    b1.setHorizontalTextPosition(AbstractButton.LEADING); //aka LEFT, for left-to-right locales
    b1.setMnemonic(KeyEvent.VK_D);
    b1.setActionCommand("disable");
 
    b2 = new JButton("Middle button", middleButtonIcon);
    b2.setVerticalTextPosition(AbstractButton.BOTTOM);
    b2.setHorizontalTextPosition(AbstractButton.CENTER);
    b2.setMnemonic(KeyEvent.VK_M);
 
    b3 = new JButton("Enable middle button", rightButtonIcon);
    //Use the default text position of CENTER, TRAILING (RIGHT).
    b3.setMnemonic(KeyEvent.VK_E);
    b3.setActionCommand("enable");
    b3.setEnabled(false);
 
    //Listen for actions on buttons 1 and 3.
    b1.addActionListener(this);
    b3.addActionListener(this);
 
    b1.setToolTipText("Click this button to disable the middle button.");
    b2.setToolTipText("This middle button does nothing when you click it.");
    b3.setToolTipText("Click this button to enable the middle button.");
 
    //Add Components to this container, using the default FlowLayout.
    add(b1);
    add(b2);
    add(b3);
  }
 
  public void actionPerformed(ActionEvent e) {
    if ("disable".equals(e.getActionCommand())) {
      b2.setEnabled(false);
      b1.setEnabled(false);
      b3.setEnabled(true);
    } else {
      b2.setEnabled(true);
      b1.setEnabled(true);
      b3.setEnabled(false);
    }
  }
 
  /** Returns an ImageIcon, or null if the path was invalid. */
  protected static ImageIcon createImageIcon(String path) {
    java.net.URL imgURL = ButtonDemo.class.getResource(path);
    if (imgURL != null) {
      return new ImageIcon(imgURL);
    } else {
      System.err.println("Couldn't find file: " + path);
      return null;
    }
  }
 
  /**
   * Create the GUI and show it.  For thread safety, 
   * this method should be invoked from the 
   * event-dispatching thread.
   */
  private static void createAndShowGUI() {
 
    //Create and set up the window.
    JFrame frame = new JFrame("ButtonDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
    //Create and set up the content pane.
    ButtonDemo newContentPane = new ButtonDemo();
    newContentPane.setOpaque(true); //content panes must be opaque
    frame.setContentPane(newContentPane);
 
    //Display the window.
    frame.pack();
    frame.setVisible(true);
  }
 
  public static void main(String[] args) {
    //Schedule a job for the event-dispatching thread:
    //creating and showing this application's GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI(); 
      }
    });
  }
}

Το παραπάνω παράδειγμα απαιτεί την χρήση των παρακάτω εικόνων buttondemoimages.zip

swing/buttons.1431318536.txt.gz · Last modified: 2015/05/11 03:28 (external edit)