Java侦听器检查对象的布尔值是否为真

Question

我有一个名为 menuBarObject 的对象。它的类隐藏了一个名为“changed”的布尔值。如果单击子菜单，则返回 true。 在我的 Mainclass 中，我构建了 menuBarObject。我可以通过一种名为“hasChanged”的方法获取更改的值。如果主方法完成了它的工作，它将所有一个名为“contentIsBuild”的方法再次设置为 false。 如果更改返回 true，我可以编写一个活跃的侦听器吗？我可以在 menuBar 类中做到这一点。但我不喜欢那个解决方案。

我的代码放入那个监听器：

if (newCustomerIsSelected) {
    //Content Area   
    JPanel contentArea = new JPanel();
    //Selection from Sub Menu
    String selectedName = menuBarObject.getSelectedCustomer();
    //Selected Customer Object / Instanze of selectecCustomer Class!
    SelectedCustomer selectedCustomerObject = new SelectedCustomer(selectedName);
    //The seleted Customer
    Customer selectedCustomer = selectedCustomerObject.getSelectedCustomer();
    //Name of selected Customer
    String dataOfSelectedCustomer = selectedCustomer.toString();
    //Creating the content Area
    setCustomerContentArea(dataOfSelectedCustomer, contentArea);
    //Call Menu Bar that content is build
    menuBarObject.contentIsBuild(true);
}

Answer 1

您可以使用 MouseListener (https://docs.oracle.com/javase/tutorial/uiswing/events/mouselistener.html) 来监听点击，而不是使用 changed 来记录点击（假设您的子菜单扩展了 Component 类，例如是 JPanel 或类似的东西）。

在您实例化子菜单的类中，您将执行以下操作：

submenu.addMouseListener(new MouseListener()
        {

            @Override
            public void mouseReleased(MouseEvent e)
            {
                // Do nothing
            }

            @Override
            public void mousePressed(MouseEvent e)
            {
                // Do nothing
            }

            @Override
            public void mouseExited(MouseEvent e)
            {
                // Do nothing
            }

            @Override
            public void mouseEntered(MouseEvent e)
            {
                // Do nothing
            }

            @Override
            public void mouseClicked(MouseEvent e)
            {
                if (newCustomerIsSelected) {
                    //Content Area   
                    JPanel contentArea = new JPanel();
                    //Selection from Sub Menu
                    String selectedName = menuBarObject.getSelectedCustomer();
                    //Selected Customer Object / Instanze of selectecCustomer Class!
                    SelectedCustomer selectedCustomerObject = new SelectedCustomer(selectedName);
                    //The seleted Customer
                    Customer selectedCustomer = selectedCustomerObject.getSelectedCustomer();
                    //Name of selected Customer
                    String dataOfSelectedCustomer = selectedCustomer.toString();
                    //Creating the content Area
                    setCustomerContentArea(dataOfSelectedCustomer, contentArea);
                    //Call Menu Bar that content is build
                    menuBarObject.contentIsBuild(true); // N.B. This would no longer need to set the changed variable to false.
                }
            }
        });

如果changed 对您的应用程序很重要，那么您可以考虑使用 PropertyChangeSupport (https://docs.oracle.com/javase/tutorial/uiswing/events/propertychangelistener.html) 来触发您自己的事件。这可能最好放在设置changed = true 的同一类中。

这看起来像：

private final PropertyChangeSupport pcs = new PropertyChangeSupport(this);

... // Other code in class

public void addChangeListener(PropertyChangeListener listener) {
    this.pcs.addPropertyChangeListener(listener);
}

...

// In the method which sets changed = true
this.pcs.firePropertyChange(null, null, null) // Args are: Property name, old value and new value - set as necessary

然后在您希望侦听器代码所在的方法中添加：

// object is the name of the instantiation of the class which sets changed = true
object.addChangeListener(new PropertyChangeListener()
        {

            @Override
            public void propertyChange(PropertyChangeEvent evt)
            {
                if (newCustomerIsSelected) {
                    //Content Area   
                    JPanel contentArea = new JPanel();
                    //Selection from Sub Menu
                    String selectedName = menuBarObject.getSelectedCustomer();
                    //Selected Customer Object / Instanze of selectecCustomer Class!
                    SelectedCustomer selectedCustomerObject = new SelectedCustomer(selectedName);
                    //The seleted Customer
                    Customer selectedCustomer = selectedCustomerObject.getSelectedCustomer();
                    //Name of selected Customer
                    String dataOfSelectedCustomer = selectedCustomer.toString();
                    //Creating the content Area
                    setCustomerContentArea(dataOfSelectedCustomer, contentArea);
                    //Call Menu Bar that content is build
                    menuBarObject.contentIsBuild(true);
                }
            }
        });

编辑：修正了错误的方法名称。