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[英]Is there any way to add a Parent to a JComponent apart from super(parent)
[英]Is there a way to get notification when JComponent is not visible anymore beucase parent is removed from collection?
假设我有一个包含3个面板的JTabbedPane的简单JFrame,第二个面板包含一个JComponent。 当“Tab 2”面板从其容器中移除时,是否有一种方式可以通知JComponent? 我的问题是JComponent可能在层次结构的深处。
显然,我在这里寻找SWING解决方案...... :)
,'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''`.
| |
| ,----------Y....................... |
| | Tab 1 | Tab 2 | Tab 3 | |
| :..........: :..................................... |
| | | |
| | | |
| | | |
| | +--------------------+ | |
| | |Some JComponent here| | |
| | +--------------------+ | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| `-----------------------------------------------------------' |
`-----------------------------------------------------------------
我试图用ancestorRemoved ()来做这件事,但没有运气......我显然做错了什么......
PS。 ASCII艺术是用JavE制作的 。
我将使用ComponentListener
来完成这项工作( CardLayout
非常接近,与JTabbedPane
相似),代码示例包含所有相关的侦听器(免责声明 - >通知阻止EDT仅作为代码示例工作,仅在此表单中)
Ancesor & HierarchyListener
有点异步,也许你有问题从AncestorListener
捕获正确的事件
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;
import java.awt.event.HierarchyEvent;
import java.awt.event.HierarchyListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.event.AncestorEvent;
import javax.swing.event.AncestorListener;
public class CardlayoutTest extends JFrame {
private static final long serialVersionUID = 1L;
public CardLayout card = new CardLayout();
public CardlayoutTest() {
JPanel pnlA = new JPanel(new BorderLayout());
pnlA.add(new JButton("A"), BorderLayout.CENTER);
JPanel pnlB = new JPanel(new BorderLayout());
pnlB.add(new JButton("B"), BorderLayout.CENTER);
JPanel pnlC = new JPanel(new BorderLayout());
pnlC.add(new JButton("C"), BorderLayout.CENTER);
setDefaultCloseOperation(EXIT_ON_CLOSE);
setLayout(card);
add(pnlA, "A");
add(pnlB, "B");
add(pnlC, "C");
pnlA.addAncestorListener(new EventHandler());
pnlB.addAncestorListener(new EventHandler());
pnlC.addAncestorListener(new EventHandler());
pnlA.addHierarchyListener(new EventHandler());
pnlB.addHierarchyListener(new EventHandler());
pnlB.addHierarchyListener(new EventHandler());
pnlA.addComponentListener(new EventHandler());
pnlB.addComponentListener(new EventHandler());
pnlB.addComponentListener(new EventHandler());
}
class EventHandler implements AncestorListener, ComponentListener, HierarchyListener {
@Override
public void ancestorAdded(AncestorEvent event) {
System.out.println("CardlayoutTest.EventHandler.ancestorAdded()");
}
@Override
public void ancestorMoved(AncestorEvent event) {
System.out.println("CardlayoutTest.EventHandler.ancestorMoved()");
}
@Override
public void ancestorRemoved(AncestorEvent event) {
System.out.println("CardlayoutTest.EventHandler.ancestorRemoved()");
}
@Override
public void hierarchyChanged(HierarchyEvent e) {
System.out.println("Components Change: " + e.getChanged());
if ((e.getChangeFlags() & HierarchyEvent.DISPLAYABILITY_CHANGED) != 0) {
if (e.getComponent().isDisplayable()) {
System.out.println("Components DISPLAYABILITY_CHANGED : " + e.getChanged());
} else {
System.out.println("Components DISPLAYABILITY_CHANGED : " + e.getChanged());
}
}
if ((e.getChangeFlags() & HierarchyEvent.SHOWING_CHANGED) != 0) {
if (e.getComponent().isDisplayable()) {
System.out.println("Components SHOWING_CHANGED : " + e.getChanged());
} else {
System.out.println("Components SHOWING_CHANGED : " + e.getChanged());
}
}
}
public void componentHidden(ComponentEvent e) {
System.out.println(e.getComponent().getClass().getName() + " --- Hidden");
}
public void componentMoved(ComponentEvent e) {
System.out.println(e.getComponent().getClass().getName() + " --- Moved");
}
public void componentResized(ComponentEvent e) {
System.out.println(e.getComponent().getClass().getName() + " --- Resized ");
}
public void componentShown(ComponentEvent e) {
System.out.println(e.getComponent().getClass().getName() + " --- Shown");
}
}
public static void main(String[] args) {
CardlayoutTest t = new CardlayoutTest();
t.setSize(500, 500);
System.out.println("CardlayoutTest.main()------------------------ FIRST");
t.card.show(t.getContentPane(), "A");
t.setVisible(true);
System.out.print("\n");
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
}
System.out.println("CardlayoutTest.main()------------------------ SECOND");
t.card.show(t.getContentPane(), "B");
System.out.print("\n");
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
}
System.out.println("CardlayoutTest.main()------------------------ THIRD");
t.card.show(t.getContentPane(), "C");
System.out.print("\n");
}
}
感谢mKorbel发布了一个很好的例子,他使用了HierarchyListener,我提出了一个我认为满足我需求的解决方案。 在这种情况下,我使用JLabel
作为需要通知的组件。
我会接受mKorbel的答案,因为他为我节省了很多时间。
这是代码:
import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.event.AncestorEvent;
import javax.swing.event.AncestorListener;
import javax.swing.JTabbedPane;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.HierarchyEvent;
import java.awt.event.HierarchyListener;
public class TestFrame extends JFrame {
private static final long serialVersionUID = 8388031406846751884L;
private JPanel contentPane;
private JTabbedPane tabbedPane;
private JLabel label; /// The component that needs to be notified when it should save its states.
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
TestFrame frame = new TestFrame();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Adds necessary listeners.
* @param argLabel
*/
private void install(JLabel argLabel) {
// ::::: HierarchyListener ::::::::::::::::::::::::::::::::::::::::::::::::::::::::
argLabel.addHierarchyListener(new HierarchyListener() {
@Override
public void hierarchyChanged(HierarchyEvent arg0) {
if ((arg0.getChangeFlags() & HierarchyEvent.DISPLAYABILITY_CHANGED) != 0) {
if (!arg0.getComponent().isDisplayable()) {
// component is not displayable due to the panel being removed
doSomething();
}
}
}
});
// ::::: AncestorListener :::::::::::::::::::::::::::::::::::::::::::::::::::::::::
argLabel.addAncestorListener(new AncestorListener() {
@Override
public void ancestorAdded(AncestorEvent arg0) {
// not interested in this one
}
@Override
public void ancestorMoved(AncestorEvent arg0) {
// not interested in this one
}
@Override
public void ancestorRemoved(AncestorEvent arg0) {
// ancestorRemoved() is useful when user navigates between tabs, and causes
// component to become invisible.
doSomething();
}
});
}
public void doSomething() {
System.out.println("Saving some state(s)...");
}
/**
* Create the frame.
*/
public TestFrame() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 693, 376);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
contentPane.setLayout(new BorderLayout(0, 0));
setContentPane(contentPane);
tabbedPane = new JTabbedPane(JTabbedPane.TOP);
// first panel
tabbedPane.add(new JPanel());
// second panel
JPanel panelWithComponents = new JPanel();
JPanel childPanel = new JPanel();
label = new JLabel("Test label");
install(label);
childPanel.add(label);
panelWithComponents.add(childPanel);
tabbedPane.add(childPanel);
// third panel
tabbedPane.add(new JPanel());
contentPane.add(tabbedPane, BorderLayout.CENTER);
JButton btnRemove = new JButton("Remove second");
btnRemove.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
tabbedPane.remove(1);
}
});
contentPane.add(btnRemove, BorderLayout.SOUTH);
} // main() method
} // TestFrame class
如果组件本身需要执行某些操作,您还可以覆盖add / removeNotify(不要忘记调用super。
import java.awt.*;
import java.awt.event.*;
import java.util.Date;
import javax.swing.*;
public class LabelWithTimer extends JLabel {
private final Timer timer;
public LabelWithTimer() {
timer = new Timer(1000, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
setText(new Date().toString());
}
});
}
@Override
public void addNotify() {
super.addNotify();
timer.start();
System.out.println("Clock started");
}
@Override
public void removeNotify() {
System.out.println("Clock stopped");
timer.stop();
super.removeNotify();
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
final JPanel clock = new JPanel(new GridBagLayout());
clock.add(new LabelWithTimer());
final JTabbedPane tabs = new JTabbedPane();
tabs.addTab("Empty", new JLabel());
tabs.setPreferredSize(new Dimension(400, 300));
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(tabs);
frame.getContentPane().add(new JButton(new AbstractAction("Add/remove clock") {
@Override
public void actionPerformed(ActionEvent e) {
if(tabs.getTabCount() == 2) {
tabs.removeTabAt(1);
}
else {
tabs.addTab("Clock", clock);
tabs.setSelectedIndex(1);
}
}
}), BorderLayout.PAGE_END);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}
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