[英]How do I make a Timer ActionListener wait for another one to stop before starting
[英]How do I wait for a timer to stop before executing code?
我在類中使用了一個Timer,該類將JPanel擴展為動畫,並且ActionListener偵聽它並進行actionPerformed運行,該過程會重新繪制並在需要時停止計時器。 但是啟動計時器的方法animatePanel在計時器運行時會繼續執行,這是我不希望的。 我希望它等待計時器停止返回。
在類的構造函數中初始化Timer,如下所示:
timer = new Timer(5, taskPerformer);
這就是它的作用。 我有一個叫animatePanel()的東西:
private ActionListener taskPerformer = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
...
if (some conditions){
...
timer.stop();
...
return;
}
...
}
};
private void animatePanel() {
...
timer.start();
System.out.println("Timer stopped."); //always executes before the timer has stopped :(
//then returns and lets the rest of my program run while the timer is still going, which is BAD
}
計時器工作正常,除了在某些情況下,animatePanel()會返回得太早並讓程序的其余部分運行,從而導致問題。
您不能在事件調度線程的上下文中執行此操作,否則將使應用程序掛起!
計時器必須在單獨的Thread
啟動。 然后,您可以利用線程監視API。
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class WaitForTimer {
public static void main(String[] args) {
new WaitForTimer();
}
public WaitForTimer() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public static class TestPane extends JPanel {
protected static final Object WAIT_FOR = new Object();
private Timer timer;
private int tickCount = 0;
private JLabel ticks;
private JButton start;
public TestPane() {
timer = new Timer(250, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
tickCount++;
if (tickCount > 10) {
tickCount = 0;
timer.stop();
synchronized (WAIT_FOR) {
WAIT_FOR.notifyAll();
}
start.setEnabled(true);
}
ticks.setText(String.valueOf(tickCount));
}
});
timer.setRepeats(true);
timer.setCoalesce(true);
ticks = new JLabel("...");
start = new JButton("Start");
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
add(ticks, gbc);
add(start, gbc);
start.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
start.setEnabled(false);
new Thread(new Runnable() {
@Override
public void run() {
System.out.println("Starting timer...");
timer.start();
synchronized (WAIT_FOR) {
try {
WAIT_FOR.wait();
} catch (InterruptedException ex) {
}
}
System.out.println("Timer finished...");
}
}).start();
}
});
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
}
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