我的自定義JDialog出現，但爲空

Question

在程序中的某一點，它打開一個JDialog，顯示有關程序運行過程中發生的事情的信息。它有幾個標籤和一個進度條，但是當對話窗口打開時，它不顯示任何內容。

這裏的自定義對話框，它的構造：

public class DataMiner implements ActionListener 
{ 
    private Hashtable<Integer, GISNode> nodeTable; 
    private Hashtable<Integer, GISLink> linkTable; 
    private int numLinesIgnored; 
    private int numLinesProcessed; 
    private int numNodes; 
    private int numLinks; 
    private int numDuplicates; 
    private int numFailedGeoCodingRequests; 
    private boolean cancelled; 

// window objects 
    private JDialog window; 
    private JLabel LinesIgnored; 
    private JLabel LinesProcessed; 
    private JLabel Nodes; 
    private JLabel Links; 
    private JLabel Duplicates; // tracks the number of equivalent data entries found. 
    private JLabel FailedGeoCodingRequests; 
    private JProgressBar progressBar; 
    private JButton cancelButton; 

    public DataMiner(JFrame parentWindow) 
    { 
     nodeTable = new Hashtable<Integer, GISNode>(1000); 
     linkTable = new Hashtable<Integer, GISLink>(1000); 

     numLinesIgnored = 0; 
     numLinesProcessed = 0; 
     numNodes = 0; 
     numLinks = 0; 
     numDuplicates = 0; 
     numFailedGeoCodingRequests = 0; 
     cancelled = false; 

     LinesIgnored = new JLabel(); 
     LinesProcessed = new JLabel(); 
     Nodes = new JLabel(); 
     Links = new JLabel(); 
     Duplicates = new JLabel(); 
     FailedGeoCodingRequests = new JLabel(); 
     cancelButton = new JButton("Cancel"); 
     progressBar = new JProgressBar(); 

     updateLabels(); // assigns a formatted string to each JLabel 
     cancelButton.addActionListener(this); 

    // initialize window 
     window = new JDialog(parentWindow); 
     window.setResizable(false); 
     window.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); 

     Container content = window.getContentPane(); 
     content.setLayout(new GridLayout(7,1)); 
     content.add(LinesProcessed); 
     content.add(Nodes); 
     content.add(Links); 
     content.add(Duplicates); 
     content.add(LinesIgnored); 
     content.add(FailedGeoCodingRequests); 
     content.add(progressBar); 
     JPanel p1 = new JPanel(); 
     p1.add(new JLabel("")); // takes up space 
     p1.add(cancelButton); 
     content.add(p1); 
     window.pack(); 
     window.setLocationRelativeTo(parentWindow); 
     window.setVisible(true); 
    } 

    (rest of the class...) 
} 

一旦這個窗口打開時，該程序的其餘部分保持執行正常的，只是這個窗口是空白。我錯過了什麼？

Answer 1

可能是因爲你卡住EventDispatchThread，對GUI不能重繪自己。有關更多信息，請參閱Concurrency的Swing教程部分。

既然你沒有提供一個合適的SSCCE我們不能再做任何事情。

Answer 2

這真的很奇怪。這段代碼對我來說很好，意思是顯示一個空的主窗口（這是正確的）和「彈出窗口」的子窗口窗口（你所說的不適合你）。我使用的NetBeans 6.8和Java 1.6在Ubuntu下：

package javaapplication2; 

import java.awt.Container; 
import java.awt.GridLayout; 
import javax.swing.JButton; 
import javax.swing.JDialog; 
import javax.swing.JFrame; 
import javax.swing.JLabel; 
import javax.swing.JPanel; 
import javax.swing.JProgressBar; 

public class MainFrame extends javax.swing.JFrame { 

    private int numLinesIgnored; 
    private int numLinesProcessed; 
    private int numNodes; 
    private int numLinks; 
    private int numDuplicates; 
    private int numFailedGeoCodingRequests; 
    private boolean cancelled; 

// window objects 
    private JDialog window; 
    private JLabel LinesIgnored; 
    private JLabel LinesProcessed; 
    private JLabel Nodes; 
    private JLabel Links; 
    private JLabel Duplicates; // tracks the number of equivalent data entries found. 
    private JLabel FailedGeoCodingRequests; 
    private JProgressBar progressBar; 
    private JButton cancelButton; 

    /** Creates new form MainFrame */ 
    public MainFrame() { 
     initComponents(); 

     JFrame parentWindow = this; 


     numLinesIgnored = 0; 
     numLinesProcessed = 0; 
     numNodes = 0; 
     numLinks = 0; 
     numDuplicates = 0; 
     numFailedGeoCodingRequests = 0; 
     cancelled = false; 

     LinesIgnored = new JLabel(); 
     LinesProcessed = new JLabel(); 
     Nodes = new JLabel(); 
     Links = new JLabel(); 
     Duplicates = new JLabel(); 
     FailedGeoCodingRequests = new JLabel(); 
     cancelButton = new JButton("Cancel"); 
     progressBar = new JProgressBar(); 

    // initialize window 
     window = new JDialog(parentWindow); 
     window.setResizable(false); 
     window.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); 

     Container content = window.getContentPane(); 
     content.setLayout(new GridLayout(7,1)); 
     content.add(LinesProcessed); 
     content.add(Nodes); 
     content.add(Links); 
     content.add(Duplicates); 
     content.add(LinesIgnored); 
     content.add(FailedGeoCodingRequests); 
     content.add(progressBar); 
     JPanel p1 = new JPanel(); 
     p1.add(new JLabel("")); // takes up space 
     p1.add(cancelButton); 
     content.add(p1); 
     window.pack(); 
     window.setLocationRelativeTo(parentWindow); 
     window.setVisible(true); 
    } 

    /** This method is called from within the constructor to 
    * initialize the form. 
    * WARNING: Do NOT modify this code. The content of this method is 
    * always regenerated by the Form Editor. 
    */ 
    @SuppressWarnings("unchecked") 
    // <editor-fold defaultstate="collapsed" desc="Generated Code"> 
    private void initComponents() { 

     setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); 

     javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); 
     getContentPane().setLayout(layout); 
     layout.setHorizontalGroup(
      layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGap(0, 400, Short.MAX_VALUE) 
     ); 
     layout.setVerticalGroup(
      layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) 
      .addGap(0, 300, Short.MAX_VALUE) 
     ); 

     pack(); 
    }// </editor-fold> 

    /** 
    * @param args the command line arguments 
    */ 
    public static void main(String args[]) { 
     java.awt.EventQueue.invokeLater(new Runnable() { 
      public void run() { 
       new MainFrame().setVisible(true); 
      } 
     }); 
    } 

    // Variables declaration - do not modify 
    // End of variables declaration 

}