JProgressBar不更新，找不到線索

Question

不錯的工作，現在我只想知道爲什麼如果我加入while循環指令System.out.println下面的進度顯示在這兩個cmd和Pgbar在桂？ ：

while(progress < 99){ 
    System.out.println("into while of PBar Thread progress = "+progress); 
    if(progress != Path.operationProgress){ 
    operationProgressBar.setValue(progress); 
    progress = Path.operationProgress; 
    operationProgressBar.repaint(); } } 

需要一些幫助身邊，我不能得到的JProgressBar更新，我 不能使用SwingWorker的，我必須解決這個問題離不開它。變量 Path.operationProgress是一個來自「Path」類的實例的靜態變量，它從另一個線程更新，所以我認爲PBar 和Path實例都在用戶線程中執行，而不是在EDT中執行 EDT。這裏是進度條的代碼：

import javax.swing.*; 
    public class Pbar extends Thread { 
     JProgressBar operationProgressBar; 
     public Pbar(JProgressBar operationProgressBar) { 
      this.operationProgressBar = operationProgressBar; 
     } 

     @Override 
     public void run() { 
      int progress = Path.operationProgress; 
      while(progress < 99) { 
       if(progress != Path.operationProgress) { 
        operationProgressBar.setValue(progress); 
        progress = Path.operationProgress; 
        operationProgressBar.repaint(); 
       }}} 
    } 

這是啓動線程的操作：

private javax.swing.JProgressBar operationProgressBar; 
private javax.swing.JLabel pathImage; 
private javax.swing.JButton simulatedAnnelingButton; 

public class TSPGUI extends javax.swing.JFrame { 

    TSPMG tspInstance; 
    Path p, result; 
    String filename = ""; 
    int neighborHood_Type = 1, i = 0; 
    // ......Constructor Stuff and init() 

private void simulatedAnnelingButtonActionPerformed(java.awt.event.ActionEvent evt) 

{
主題SA =新的Thread（）{ @覆蓋 公共無效的run （）{ result = p.SimulatedAnnealing（neighborHood_Type）; String lastCostString = result.Cost（）+「」; lastCostLabel.setText（lastCostString）; }}; sa.start（）; Pbar pb = new Pbar（operationProgressBar）; pb.start（）; } // 一些其他的東西...... }

Answer 1

我會使用PropertyChangeListener來讓退火進度值成爲類的「綁定」屬性。如果需要的話，任何觀察者都可以關注這個屬性。例如：

import java.awt.GridLayout; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.beans.PropertyChangeEvent; 
import java.beans.PropertyChangeListener; 

import javax.swing.*; 
import javax.swing.event.SwingPropertyChangeSupport; 

@SuppressWarnings("serial") 
public class TspGui2 extends JPanel { 
    private static final String ANNEALING_PROGRESS = "Annealing Progress"; 
    private JProgressBar progBar = new JProgressBar(0, 100); 
    private JLabel valueLabel = new JLabel(); 
    private JButton beginAnnealingBtn = new JButton("Begin Annealing"); 
    private MyAnnealing myAnnealing = new MyAnnealing(this); 

    public TspGui2() { 
     beginAnnealingBtn.addActionListener(new ActionListener() { 

     @Override 
     public void actionPerformed(ActionEvent e) { 
      beginAnnealing(); 
     } 
     }); 
     myAnnealing.addPropertyChangeListener(new PropertyChangeListener() { 

     @Override 
     public void propertyChange(PropertyChangeEvent evt) { 
      if (evt.getPropertyName().equals(MyAnnealing.ANNEALING)) { 
       // be sure this is done on the EDT 
       SwingUtilities.invokeLater(new Runnable() { 
        public void run() { 
        int annealedValue = myAnnealing.getAnnealedValue(); 
        setValue(annealedValue); 
        if (annealedValue >= MyAnnealing.MAX_ANNEALED_VALUE) { 
         beginAnnealingBtn.setEnabled(true); 
        } 
        } 
       }); 
      } 
     } 
     }); 
     progBar.setString(ANNEALING_PROGRESS); 
     progBar.setStringPainted(true); 

     JPanel northPanel = new JPanel(new GridLayout(1, 0)); 
     northPanel.add(beginAnnealingBtn); 
     northPanel.add(valueLabel); 

     setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS)); 
     add(northPanel); 
     add(progBar); 
    } 

    public void setValue(int value) { 
     valueLabel.setText("Value:" + value); 
     progBar.setValue(value); 
    } 

    public void beginAnnealing() { 
     beginAnnealingBtn.setEnabled(false); 
     setValue(0); 
     myAnnealing.reset(); 
     new Thread(new Runnable() { 
     public void run() { 
      myAnnealing.beginAnnealing(); 
     } 
     }).start(); 
    } 

    private static void createAndShowGui() { 
     TspGui2 mainPanel = new TspGui2(); 

     JFrame frame = new JFrame("TspGui2"); 
     frame.setDefaultCloseOperation(JFrame.EXIT_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 MyAnnealing { 
    public static final String ANNEALING = "Annealing"; 
    public static final int MAX_ANNEALED_VALUE = 100; 
    private SwingPropertyChangeSupport propChangeSupport = 
     new SwingPropertyChangeSupport(this); 
    private TspGui2 gui; 
    private int annealedValue; 

    public MyAnnealing(TspGui2 gui) { 
     this.gui = gui; 
    } 

    public void addPropertyChangeListener(
     PropertyChangeListener listener) { 
     propChangeSupport.addPropertyChangeListener(listener); 
    } 

    public void removePropertyChangeListener(
     PropertyChangeListener listener) { 
     propChangeSupport.removePropertyChangeListener(listener); 
    } 

    public void reset() { 
     setAnnealedValue(0); 
    } 

    // simulate some long process... 
    public void beginAnnealing() { 
     long sleepDelay = 100; 
     while (annealedValue < MAX_ANNEALED_VALUE) { 
     setAnnealedValue(annealedValue + 1); 
     try { 
      Thread.sleep(sleepDelay); 
     } catch (InterruptedException e) { 
      e.printStackTrace(); 
     } 
     } 
    } 

    public int getAnnealedValue() { 
     return annealedValue; 
    } 

    private void setAnnealedValue(int value) { 
     final int oldValue = this.annealedValue; 
     this.annealedValue = value; 
     propChangeSupport.firePropertyChange(ANNEALING, oldValue, annealedValue); 
    } 
} 

Answer 2

如果您不能使用SwingWorker然後用SwingUtilities.invokeLater，如：

if (progress != Path.operationProgress) { 
    final int progressCopy = progress; // Probably not final so copy is needed 
    SwingUtilities.invokeLater(new Runnable() { 
     @Override 
     void run() { 
      operationsProgressBar.setValue(progressCopy); 
     } 
    }); 
} 

注：執行此操作時，在run使用任何事物都有是最終的，或者必須有其他措施來訪問這些變量。這個代碼在這方面是象徵性的。

您需要對事件派發線程外的Swing組件執行操作，但沒有辦法解決此問題。