Java Exit MouseListener, wenn CheckBoxMenuItem nicht markiert ist

Question

Ich habe eine Menüleiste mit einigen Einträgen erstellt und eine davon ist ein CheckBoxMenuItem. Ich möchte ein MouseListener-Ereignis ausführen, wenn dieses Element aktiviert ist und ich möchte, dass es damit aufhört, wenn ich es abnehme.

Zusätzlich habe ich ein JPanel erstellt, auf dem Mausereignisse durchgeführt werden können und eine Statusleiste.

Um dieses Problem zu lösen, dachte ich an einer if-Schleife:

clickItem.addActionListener(new ActionListener() { 
       public void actionPerformed(ActionEvent e) { 
        if (clickItem.getState() == true) { 
         mousePanel.addMouseListener(mouseHandler); 
         mousePanel.addMouseMotionListener(mouseHandler); 
        } 
        else if (clickItem.getState() == false) {       
         statusBar.setText("Mouse Mode OFF"); 
        }  
       } 
      }); 

Aber wenn ich mein Programm mit diesem Code ausführen, wobei die Platte mit den Maus-Ereignissen schaltet nicht ab, wenn ich das Kontrollkästchen deaktivieren .

Was ist los?

Edit:

private JLabel statusBar; 
private JPanel mousePanel; 


private class HandlerClass implements MouseListener, MouseMotionListener { 

// Mouse events for MouseListener 

public void mouseClicked(MouseEvent event) { 

statusBar.setText(String.format("Clicked at %d %d", event.getX(), event.getY())); 
     } 
... 

HandlerClass mouseHandler = new HandlerClass(); 

Answer 1

OK, Overkill, ich weiß, aber betrachten eine Model-View-Controller-einrichten zu tun, wo die Sicht so dumm wie möglich ist. Alles was es macht, ist seine Komponenten für die Anzeige zu erstellen und das war's. Das Modell enthält den Status des Kontrollkästchens, es enthält die Position und den Status der Maus - ob sie gedrückt wurde, gezogen wird oder nicht. Das Modell kann Java Beans Eigenschaft Listener-Unterstützung verwenden, sodass der Controller Listener hinzufügen und über Statusänderungen benachrichtigt werden kann. Das Ganze könnte wie folgt aussehen:

import javax.swing.*; 

// main program that creates the model and view and plugs them into 
// the controller 
public class SimpleMvc { 
    private static void createAndShowGui() { 
     SimpleModel model = new SimpleModel(); 
     SimpleView view = new SimpleView(); 
     new SimpleController(model, view); 

     JFrame frame = new JFrame("Simple MVC"); 
     frame.setJMenuBar(view.getJMenuBar()); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.getContentPane().add(view.getMainPanel()); 
     frame.pack(); 
     frame.setLocationRelativeTo(null); 
     frame.setVisible(true); 
    } 

    public static void main(String[] args) { 
     SwingUtilities.invokeLater(() -> createAndShowGui()); 
    } 
} 

import java.awt.Point; 
import java.beans.PropertyChangeListener; 
import javax.swing.event.SwingPropertyChangeSupport; 

// model that holds the state of the program 
// and notifies listeners of changes in this state 
public class SimpleModel { 
    public static final String CHECK_STATE = "check state"; 
    public static final String MOUSE_POINT = "mouse point"; 
    public static final String MOUSE_STATE = "mouse state"; 
    private SwingPropertyChangeSupport support = new SwingPropertyChangeSupport(this); 
    private boolean checkState = false; 
    private Point mousePoint = null; 
    private SimpleMouseState mouseState = SimpleMouseState.RELEASED; 

    public boolean isCheckState() { 
     return checkState; 
    } 

    public void setCheckState(boolean checkState) { 
     boolean oldValue = this.checkState; 
     boolean newValue = checkState; 
     this.checkState = checkState; 

     // notify the listeners of the change 
     support.firePropertyChange(CHECK_STATE, oldValue, newValue); 
    } 

    public void addPropertyChangeListener(String propertyName, PropertyChangeListener listener) { 
     support.addPropertyChangeListener(propertyName, listener); 
    } 

    public Point getMousePoint() { 
     return mousePoint; 
    } 

    public void setMousePoint(Point mousePoint) { 
     Point oldValue = this.mousePoint; 
     Point newValue = mousePoint; 
     this.mousePoint = mousePoint; 
     support.firePropertyChange(MOUSE_POINT, oldValue, newValue); 
    } 

    public SimpleMouseState getMouseState() { 
     return mouseState; 
    } 

    public void setMouseState(SimpleMouseState mouseState) { 
     SimpleMouseState oldValue = this.mouseState; 
     SimpleMouseState newValue = mouseState; 
     this.mouseState = mouseState; 
     support.firePropertyChange(MOUSE_STATE, oldValue, newValue); 
    }  
} 

// enum to encapsulate the mouse state 
public enum SimpleMouseState { 
    PRESSED("Pressed"), 
    DRAGGED("Dragged"), 
    RELEASED("Released"); 
    private String text; 

    private SimpleMouseState(String text) { 
     this.text = text; 
    } 

    public String getText() { 
     return text; 
    } 
} 

import java.awt.BorderLayout; 
import java.awt.Dimension; 
import java.awt.FlowLayout; 

import javax.swing.BorderFactory; 
import javax.swing.JComponent; 
import javax.swing.JLabel; 
import javax.swing.JMenuBar; 
import javax.swing.JPanel; 

// our view, again make it as dumb as possible 
// all the "brains" are in the model and controller 
public class SimpleView { 
    private static final int PREF_W = 600; 
    private static final int PREF_H = 450; 
    private JComponent mainPanel = new JPanel(); 
    private JMenuBar menuBar = new JMenuBar(); 
    private JLabel statusLabel = new JLabel(" "); 

    public SimpleView() { 
     JPanel statusPanel = new JPanel(new FlowLayout(FlowLayout.LEADING)); 
     statusPanel.setBorder(BorderFactory.createEtchedBorder()); 
     statusPanel.add(statusLabel); 

     mainPanel.setPreferredSize(new Dimension(PREF_W, PREF_H)); 
     mainPanel.setLayout(new BorderLayout()); 
     mainPanel.add(statusPanel, BorderLayout.PAGE_END); 
    } 

    public JComponent getMainPanel() { 
     return mainPanel; 
    } 

    public JMenuBar getJMenuBar() { 
     return menuBar; 
    } 

    public void setStatusMessage(String text) { 
     statusLabel.setText(text); 
    } 

} 

import java.awt.Point; 
import java.awt.event.ItemEvent; 
import java.awt.event.ItemListener; 
import java.awt.event.MouseAdapter; 
import java.awt.event.MouseEvent; 
import java.beans.PropertyChangeEvent; 
import java.beans.PropertyChangeListener; 

import javax.swing.JCheckBoxMenuItem; 
import javax.swing.JMenu; 

// our controller, where we hook everything together 
public class SimpleController { 
    public static final String MOUSE_MODE_OFF = "Mouse Mode OFF"; 
    public static final String MOUSE_MODE_ON = "Mouse Mode ON"; 
    private SimpleModel model; 
    private SimpleView view; 
    private JCheckBoxMenuItem clickItem = new JCheckBoxMenuItem("Click Me"); 

    public SimpleController(SimpleModel model, SimpleView view) { 
     this.model = model; 
     this.view = view; 
     view.setStatusMessage(MOUSE_MODE_OFF); 

     // Add view listeners 
     clickItem.addItemListener(new ViewClickItemListener()); 
     JMenu menu = new JMenu("Menu"); 
     menu.add(clickItem); 
     view.getJMenuBar().add(menu); 
     ViewMouseListener mouseListener = new ViewMouseListener(); 
     view.getMainPanel().addMouseListener(mouseListener); 
     view.getMainPanel().addMouseMotionListener(mouseListener); 

     // add model listeners 
     model.addPropertyChangeListener(SimpleModel.CHECK_STATE, new ModelCheckStateListener()); 
     model.addPropertyChangeListener(SimpleModel.MOUSE_POINT, new ModelMousePointListener()); 
     model.addPropertyChangeListener(SimpleModel.MOUSE_STATE, new ModelMouseStateListener()); 
    } 

    private class ModelMousePointListener implements PropertyChangeListener { 
     @Override 
     public void propertyChange(PropertyChangeEvent evt) { 
      Point p = (Point) evt.getNewValue(); 
      String text = model.getMouseState().getText(); 
      view.setStatusMessage(String.format("%s at [%03d, %03d]", text, p.x, p.y));    
     } 
    } 

    private class ModelMouseStateListener implements PropertyChangeListener { 
     @Override 
     public void propertyChange(PropertyChangeEvent evt) { 
      Point p = model.getMousePoint(); 
      String text = model.getMouseState().getText(); 
      if (p == null) { 
       return; 
      } 
      view.setStatusMessage(String.format("%s at [%03d, %03d]", text, p.x, p.y));    
     } 
    } 

    private class ModelCheckStateListener implements PropertyChangeListener { 
     @Override 
     public void propertyChange(PropertyChangeEvent evt) { 
      if ((boolean) evt.getNewValue()) { 
       view.setStatusMessage(MOUSE_MODE_ON); 
      } else { 
       view.setStatusMessage(MOUSE_MODE_OFF); 
      } 
     } 
    } 

    private class ViewClickItemListener implements ItemListener { 
     @Override 
     public void itemStateChanged(ItemEvent e) { 
      model.setCheckState(e.getStateChange() == ItemEvent.SELECTED); 
     } 
    } 

    private class ViewMouseListener extends MouseAdapter { 
     @Override 
     public void mousePressed(MouseEvent e) { 
      // check model's check state first 
      if (model.isCheckState()) { 
       // mouse listener is active -- change the model's state 
       model.setMouseState(SimpleMouseState.PRESSED); 
       model.setMousePoint(e.getPoint()); 
      } // else do nothing 
     } 

     @Override 
     public void mouseDragged(MouseEvent e) { 
      // similar to mouse pressed 
      if (model.isCheckState()) { 
       model.setMouseState(SimpleMouseState.DRAGGED); 
       model.setMousePoint(e.getPoint()); 
      } // else do nothing    
     } 

     @Override 
     public void mouseReleased(MouseEvent e) { 
      // similar to mouse pressed 
      if (model.isCheckState()) { 
       model.setMouseState(SimpleMouseState.RELEASED); 
       model.setMousePoint(e.getPoint()); 
      } // else do nothing    
     } 
    } 
}