下面的示例允许显示、隐藏、处理和关闭窗口(通过发送事件)。
示例显示，该窗口只打开一次——在第一次设置为可见时。即使一个窗口被释放，然后再次显示，它也不会经历“打开”事件。
为什么？
如何在不编写处理程序和跟踪此事件的情况下知道窗口是否打开？
如何关闭窗口，使其在设置可见时再次经历打开事件？ IE。如何将窗口对象返回到初始状态？
是否有任何其他状态或事件可以具有所需的属性？
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.AbstractAction;
import javax.swing.AbstractListModel;
import javax.swing.ComboBoxModel;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.event.ListDataListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class Tester_JFrame_Closing_01 {
private static Logger log = LoggerFactory.getLogger(Tester_JFrame_Closing_01.class);
protected static Toolkit toolkit = Toolkit.getDefaultToolkit();
protected static EventQueue eventQueue = toolkit.getSystemEventQueue();
public static enum CloseOperation {
DO_NOTHING_ON_CLOSE(JFrame.DO_NOTHING_ON_CLOSE),
HIDE_ON_CLOSE(JFrame.HIDE_ON_CLOSE),
DISPOSE_ON_CLOSE(JFrame.DISPOSE_ON_CLOSE),
EXIT_ON_CLOSE(JFrame.EXIT_ON_CLOSE)
;
public static ComboBoxModel newModel() {
return new ComboBoxModel() {
private CloseOperation selected = HIDE_ON_CLOSE;
@SuppressWarnings("serial")
private final AbstractListModel core = new AbstractListModel() {
@Override
public int getSize() {
return values().length;
}
@Override
public Object getElementAt(int index) {
return values()[index];
}
};
@Override
public int getSize() {
return core.getSize();
}
@Override
public Object getElementAt(int index) {
return core.getElementAt(index);
}
@Override
public void addListDataListener(ListDataListener l) {
core.addListDataListener(l);
}
@Override
public void removeListDataListener(ListDataListener l) {
core.removeListDataListener(l);
}
@Override
public void setSelectedItem(Object anItem) {
selected = (CloseOperation) anItem;
}
@Override
public Object getSelectedItem() {
return selected;
}
};
}
public final int Value;
private CloseOperation(int value) {
this.Value = value;
}
@Override
public String toString() {
switch(this) {
case DISPOSE_ON_CLOSE:
return "DISPOSE_ON_CLOSE";
case HIDE_ON_CLOSE:
return "HIDE_ON_CLOSE";
case DO_NOTHING_ON_CLOSE:
return "DO_NOTHING_ON_CLOSE";
case EXIT_ON_CLOSE:
return "EXIT_ON_CLOSE";
default:
return "<UNKNOWN>";
}
}
}
public static void main(String[] args) {
WindowAdapter windowAdapter = new WindowAdapter() {
@Override
public void windowClosed(WindowEvent e) {
log.debug("windowClosed");
}
@Override
public void windowClosing(WindowEvent e) {
log.debug("windowClosing");
}
@Override
public void windowOpened(WindowEvent e) {
log.debug("windowOpened");
}
};
final JFrame frame = new JFrame("Controlled window");
frame.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
frame.addWindowListener(windowAdapter);
final WindowEvent closeEvent = new WindowEvent(frame, WindowEvent.WINDOW_CLOSING);
@SuppressWarnings("serial")
AbstractAction closeAction = new AbstractAction("close") {
@Override
public void actionPerformed(ActionEvent e) {
eventQueue.postEvent(closeEvent);
}
};
@SuppressWarnings("serial")
AbstractAction hideAction = new AbstractAction("hide") {
@Override
public void actionPerformed(ActionEvent e) {
frame.setVisible(false);
}
};
@SuppressWarnings("serial")
AbstractAction showAction = new AbstractAction("show") {
@Override
public void actionPerformed(ActionEvent e) {
frame.setVisible(true);
}
};
@SuppressWarnings("serial")
AbstractAction disposeAction = new AbstractAction("dispose") {
@Override
public void actionPerformed(ActionEvent e) {
frame.dispose();
}
};
JButton closeButton = new JButton(closeAction);
JButton hideButton = new JButton(hideAction);
JButton showButton = new JButton(showAction);
JButton disposeButton = new JButton(disposeAction);
ComboBoxModel closeOperationModel = CloseOperation.newModel();
final JComboBox closeOperationCombo = new JComboBox(closeOperationModel);
closeOperationCombo.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
log.debug("closeOperationCombo.actionPerformed({})", e);
frame.setDefaultCloseOperation(((CloseOperation)closeOperationCombo.getSelectedItem()).Value);
}
});
JPanel buttonPanel = new JPanel();
buttonPanel.setLayout(new FlowLayout());
buttonPanel.add(showButton);
buttonPanel.add(hideButton);
buttonPanel.add(disposeButton);
buttonPanel.add(closeButton);
buttonPanel.add(closeOperationCombo);
JFrame controlFrame = new JFrame("Controller window");
controlFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
controlFrame.setLayout(new FlowLayout());
controlFrame.add(buttonPanel, BorderLayout.SOUTH);
controlFrame.pack();
controlFrame.setLocation(100, 100);
controlFrame.setVisible(true);
frame.setBounds(100, 100 + controlFrame.getHeight(), controlFrame.getWidth(), 480);
}
}
不可思议
他们有一个名为 Window.state 的字段，他们甚至不初始化(因此它为零)，然后他们在 show() 方法中测试一次如果为 0，则将其设置为 1。这是唯一使用 state 的地方，这里 windowOpened 被触发。没有代码可以在任何地方将 state 返回到 0。此外，他们在 Frame 子类中放弃了这个 state 变量，并用一个具有相同名称的新变量覆盖它，该变量按位保存一些新状态，包括图标化和类似状态，并忘记打开位!酷!
最佳答案
how to return window object back to initial state?
如果您想将变量和组件返回到初始状态，那么我认为您需要重新创建窗口。
How to close window so that it undergo open event again on set visible?
您可以通过执行以下操作自行跟踪窗口的关闭/打开:
WindowAdapter windowAdapter = new WindowAdapter()
{
boolean closed = false;
@Override
public void windowClosed(WindowEvent e) {
closed = true;
System.out.println("windowClosed");
}
@Override
public void windowClosing(WindowEvent e) {
System.out.println("windowClosing");
}
@Override
public void windowOpened(WindowEvent e) {
System.out.println("windowOpened");
closed = false;
}
@Override
public void windowActivated(WindowEvent e) {
System.out.println("windowActivated");
if (closed)
windowOpened(e);
}
};
为了使“关闭”按钮起作用，您还需要使用:
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
关于java - 什么时候开窗？如何在不监听窗口事件的情况下知道窗口已打开？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15260285/