Swing – 更新标签

我有一个消息标签和一个提交按钮。 将多次按下提交按钮，每次按下的操作最多可能需要一分钟。

按下按钮时，我想将消息设置为空，在任务完成后，我想将消息设置为“完成”。

private void submitActionPerformed(java.awt.event.ActionEvent evt) { message = ""; updateMessageLabel(); doTheTask(); /* this update is apply to the label after completion */ message = "Complete"; } 

是否可以在运行submitActionPerformed()方法之前（或在方法中）更新该消息标签，但是在单击该按钮之后？

Answer 1

是的，您可以使用SwingWorker线程执行此操作，在currentThread的execute()方法中execute()所有pre submitActionPerformed()活动，如更新标签，并使用工作Thread调用doTheTask()作为后台作业。

我建议您阅读本文档以获取有关SwingWorker Thread的参考

Answer 2

虽然Swing并发教程已经包含了一些关于如何在Swing中处理并发性的非常好的示例，但是在下面找一个例子

• 包含一个复选框，用于certificateUI仍处于活动状态
• 有一个进度条，从SwingWorker更新

• 有一个标签，一旦SwingWorker完成就会更新

   import javax.swing.JCheckBox; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JProgressBar; import javax.swing.SwingWorker; import java.awt.BorderLayout; import java.awt.EventQueue; import java.lang.reflect.InvocationTargetException; import java.util.List; import java.util.concurrent.ExecutionException; public class SwingWorkerExample { private static JProgressBar PROGRESS_BAR; private static JLabel OUTPUT_LABEL; private static JFrame createGUI(){ JFrame testFrame = new JFrame( "TestFrame" ); PROGRESS_BAR = new JProgressBar( ); PROGRESS_BAR.setMinimum( 0 ); PROGRESS_BAR.setMaximum( 100 ); OUTPUT_LABEL = new JLabel( "Processing" ); testFrame.getContentPane().add( PROGRESS_BAR, BorderLayout.CENTER ); testFrame.getContentPane().add( OUTPUT_LABEL, BorderLayout.SOUTH ); //add a checkbox as well to proof the UI is still responsive testFrame.getContentPane().add( new JCheckBox( "Click me to proof UI is responsive" ), BorderLayout.NORTH ); testFrame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE ); return testFrame; } public static void main( String[] args ) throws InvocationTargetException, InterruptedException { EventQueue.invokeAndWait( new Runnable() { @Override public void run() { JFrame frame = createGUI(); frame.pack(); frame.setVisible( true ); } } ); //start the SwingWorker outside the EDT MySwingWorker worker = new MySwingWorker( PROGRESS_BAR, OUTPUT_LABEL ); worker.execute(); } private static class MySwingWorker extends SwingWorker{ private final JProgressBar fProgressBar; private final JLabel fLabel; private MySwingWorker( JProgressBar aProgressBar, JLabel aLabel ) { fProgressBar = aProgressBar; fLabel = aLabel; } @Override protected String doInBackground() throws Exception { int maxNumber = 10; for( int i = 0; i < maxNumber; i++ ){ Thread.sleep( 2000 );//simulate long running process double factor = ((double)(i+1) / maxNumber); System.out.println("Intermediate results ready"); publish( factor );//publish the progress } return "Finished"; } @Override protected void process( List aDoubles ) { //update the percentage of the progress bar that is done int amount = fProgressBar.getMaximum() - fProgressBar.getMinimum(); fProgressBar.setValue( ( int ) (fProgressBar.getMinimum() + ( amount * aDoubles.get( aDoubles.size() - 1 ))) ); } @Override protected void done() { try { fLabel.setText( get() ); } catch ( InterruptedException e ) { e.printStackTrace(); } catch ( ExecutionException e ) { e.printStackTrace(); } } } }