Java 具有不可见内容的导致睡眠的帧
我有一个带有菜单栏菜单的框架,当我选择菜单项时,我希望程序显示一条消息,然后几秒钟后(通过睡眠功能)自动关闭该消息 但与此相反,我得到的是一条空消息(带有不可见内容的jdialog): 如果删除关闭消息,它的内容将在睡眠时间后出现 我需要改变什么才能得到正确的结果 我想得到这个: 完整工作代码:Java 具有不可见内容的导致睡眠的帧,java,swing,sleep,jdialog,jmenubar,Java,Swing,Sleep,Jdialog,Jmenubar,我有一个带有菜单栏菜单的框架,当我选择菜单项时,我希望程序显示一条消息,然后几秒钟后(通过睡眠功能)自动关闭该消息 但与此相反,我得到的是一条空消息(带有不可见内容的jdialog): 如果删除关闭消息,它的内容将在睡眠时间后出现 我需要改变什么才能得到正确的结果 我想得到这个: 完整工作代码: import java.awt.Dimension; import java.awt.GridLayout; import java.awt.event.ActionEvent; import ja
import java.awt.Dimension;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import java.util.concurrent.TimeUnit;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.SwingUtilities;
public class MessageSleepTest extends JDialog {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable(){
public void run(){
new Frame("frame with menubar");
}
});
}
}
class Message extends JDialog {
public Message() {
this.setLayout(new GridLayout(0, 1));
this.add(new JLabel("Displaying this message for 3 seconds and then closing it...", JLabel.CENTER));
this.setAlwaysOnTop(true);
this.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
this.pack();
this.setLocationRelativeTo(null);
this.setVisible(true);
}
}
class Frame extends JFrame{
public Frame(String title){
super(title);
setJMenuBar(new MenuBar());
setPreferredSize(new Dimension(500, 300));
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
setLocationRelativeTo(null); // center the frame
setVisible(true);
}
}
class MenuBar extends JMenuBar implements ActionListener{
public static JMenuItem itmOpen;
public MenuBar() {
JMenu menuFile = new JMenu("File");
itmOpen = new JMenuItem("Open...");
itmOpen.addActionListener(this);
add(menuFile);
menuFile.add(itmOpen);
}
@Override
public void actionPerformed(ActionEvent e) {
JMenuItem source = (JMenuItem)e.getSource();
if(source == itmOpen){
JDialog message = new Message();
try {
TimeUnit.SECONDS.sleep(3);
} catch (InterruptedException ex) {
ex.printStackTrace();
}
WindowEvent windowClosing = new WindowEvent(message, WindowEvent.WINDOW_CLOSING);
message.dispatchEvent(windowClosing);
}
}
}
您有线程问题:
sleep
是在AWT的事件调度线程上执行的,它完成AWT和Swing中的所有事件处理工作。因此,当您单击菜单项时,它会为消息
创建对象,但会被setVisible()
方法卡住,该方法通常会向JDialog发送一个事件以进行布局和显示。此消息进入EDT队列,在事件处理程序(执行的actionPerformed
方法)完成后,将被处理。然而,睡眠是介于两者之间的
因此,请尝试以下方法:
@Override
public void actionPerformed(ActionEvent e) {
JMenuItem source = (JMenuItem) e.getSource();
if (source == itmOpen) {
final JDialog message = new Message();
new Thread( new Runnable() {
@Override
public void run() {
try {
TimeUnit.SECONDS.sleep(3);
} catch (InterruptedException ex) {
// Do nothing with it
}
WindowEvent windowClosing = new WindowEvent(message, WindowEvent.WINDOW_CLOSING);
message.dispatchEvent(windowClosing);
}
}).start();
}
}
使用swing.Timer的另一个解决方案
@Override
public void actionPerformed(ActionEvent e) {
JMenuItem source = (JMenuItem)e.getSource();
if(source == itmOpen){
JDialog message = new Message();
Timer timer = new Timer(1000 * 3, new ActionListener() {
public void actionPerformed(ActionEvent e) {
WindowEvent windowClosing = new WindowEvent(message, WindowEvent.WINDOW_CLOSING);
message.dispatchEvent(windowClosing);
}
});
timer.setRepeats(false);
timer.start();
}
}
非常感谢您的解释!你的方法奏效了。