我有一个使用的GUI JProgressBar
。GUI具有JBUTTONs
调用以下代码的代码:
public void updateProgressBar(int x) {
System.out.println(javax.swing.SwingUtilities.isEventDispatchThread());
healthBar.setValue(x);
}
但是我也做了一个循环,定期调用相同的方法。
public class Loop implements Runnable {
public void run() {
while (true) { Thread.sleep(2000); updateProgressBar(0); }
}
}
现在,据我所知,任何更改我的GUI的操作都需要从EDT执行。JProgressBar.setValue(x)
更改我的GUI,然后从Loop类调用它时,isEventDispatchThread
检查将失败,这一切都很好且不稳定。但是,我不明白的是,这是否也意味着我应该使用SwingUtilities.invokeLater()
on setValue()
。我担心的是,由于我不知道setValue()
实际的工作方式,因此我invokeLater()
不必要地使用了它,甚至破坏了使用它的东西。
我不知道如何问我的问题,还有以下更好的方法:如果我不知道更改GUI的方法不是从EDT调用的,那我还知道我必须使用invokeLater()
吗?
一种可能的解决方案是创建一种方法,该方法检查线程是否为EDT,如果是,则直接更新该条,否则将其在EDT上排队:
public void updateProgressBar(int value) {
progressBar.setValue(value);
}
public void safeUpdateProgressBar(final int value) {
if (SwingUtilities.isEventDispatchThread()) {
updateProgressBar(value);
} else {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
updateProgressBar(value);
}
});
}
}
但是有很多方法可以给这只猫蒙皮。例如,
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.*;
public class ProgExample extends JPanel {
private JProgressBar progressBar = new JProgressBar(0, 100);
public ProgExample() {
progressBar.setBorderPainted(true);
progressBar.setStringPainted(true);
add(progressBar);
add(new JButton(new ProgressAction1("Action 1", KeyEvent.VK_1, this)));
add(new JButton(new ProgressAction2("Action 2", KeyEvent.VK_2, this)));
add(new JButton(new ProgressAction3("Action 3", KeyEvent.VK_3, this)));
}
public void updateProgressBar(int value) {
progressBar.setValue(value);
}
public void safeUpdateProgressBar(final int value) {
if (SwingUtilities.isEventDispatchThread()) {
updateProgressBar(value);
} else {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
updateProgressBar(value);
}
});
}
}
private static void createAndShowGui() {
ProgExample mainPanel = new ProgExample();
JFrame frame = new JFrame("ProgExample");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class ProgressAction1 extends AbstractAction {
private static final int MAX_VALUE = 100;
protected static final long SLEEP_TIME = 100;
protected static final int STEP = 2;
private ProgExample gui;
public ProgressAction1(String name, int mnemonic, ProgExample gui) {
super(name);
putValue(MNEMONIC_KEY, mnemonic);
this.gui = gui;
}
@Override
public void actionPerformed(ActionEvent e) {
new Thread(new Runnable() {
private int value = 0;
@Override
public void run() {
while (value <= MAX_VALUE) {
gui.safeUpdateProgressBar(value);
value += STEP;
try {
Thread.sleep(SLEEP_TIME);
} catch (InterruptedException e) {}
}
gui.safeUpdateProgressBar(MAX_VALUE);
}
}).start();
}
}
class ProgressAction2 extends AbstractAction {
private static final int MAX_VALUE = 100;
protected static final long SLEEP_TIME = 100;
protected static final int STEP = 2;
private ProgExample gui;
public ProgressAction2(String name, int mnemonic, ProgExample gui) {
super(name);
putValue(MNEMONIC_KEY, mnemonic);
this.gui = gui;
}
@Override
public void actionPerformed(ActionEvent e) {
final SwingWorker<Void, Void> worker = new SwingWorker<Void, Void>() {
private int value = 0;
@Override
protected Void doInBackground() throws Exception {
while (value <= MAX_VALUE) {
setProgress(value);
value += STEP;
try {
Thread.sleep(SLEEP_TIME);
} catch (InterruptedException e) {}
}
setProgress(MAX_VALUE);
return null;
}
};
worker.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent pcEvt) {
if ("progress".equals(pcEvt.getPropertyName())) {
gui.updateProgressBar(worker.getProgress());
}
}
});
worker.execute();
}
}
class ProgressAction3 extends AbstractAction {
private static final int MAX_VALUE = 100;
protected static final int SLEEP_TIME = 100;
protected static final int STEP = 2;
private ProgExample gui;
public ProgressAction3(String name, int mnemonic, ProgExample gui) {
super(name);
putValue(MNEMONIC_KEY, mnemonic);
this.gui = gui;
}
@Override
public void actionPerformed(ActionEvent e) {
new Timer(SLEEP_TIME, new ActionListener() {
int value = 0;
@Override
public void actionPerformed(ActionEvent e) {
if (value <= MAX_VALUE) {
gui.updateProgressBar(value);
value += STEP;
} else {
gui.updateProgressBar(MAX_VALUE);
((Timer) e.getSource()).stop();
}
}
}).start();
}
}
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