獲取異常：java.lang.IllegalArgumentException：不能添加到佈局：約束必須是一個字符串（或null）

我正在實現瀏覽器種類的項目，我收到一個異常。獲取異常：java.lang.IllegalArgumentException：不能添加到佈局：約束必須是一個字符串（或null）

import java.awt.BorderLayout; 
import java.awt.Dimension; 
import java.awt.GridBagConstraints; 
import java.awt.Insets; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 
import javax.swing.SwingUtilities; 
import chrriis.dj.nativeswing.swtimpl.NativeInterface; 
import chrriis.dj.nativeswing.swtimpl.components.JWebBrowser; 

public class WebPageDisplay extends JPanel{ 

    public WebPageDisplay() { 

     super(new BorderLayout()); 
     try{ 
     JPanel webBrowserPanel = new JPanel(new BorderLayout()); 
     // webBrowserPanel.setBorder(BorderFactory.createTitledBorder("Native Web Browser component")); 
     final JWebBrowser webBrowser = new JWebBrowser(); 
     webBrowser.setBarsVisible(false); 
     webBrowser.setStatusBarVisible(true); 
     webBrowserPanel.add(webBrowser, BorderLayout.CENTER); 
     add(webBrowserPanel, BorderLayout.CENTER); 
        webBrowser.navigate("www.google.com"); 
     JScrollPane scrollPane = new JScrollPane(); 
     Dimension preferredSize = scrollPane.getPreferredSize(); 
     preferredSize.height += 20; 
     scrollPane.setPreferredSize(preferredSize); 
//  add(scrollPane, BorderLayout.NORTH); 
     add(scrollPane,new GridBagConstraints(0, 2, 2, 1, 1.0, 1.0, GridBagConstraints.CENTER, 
      GridBagConstraints.BOTH, new Insets(0, 0, 0, 0), 0, 0)); 

     }catch(Exception e){ 
      e.printStackTrace(); 

     } 
     } 

    public static void main(String[] args){ 
     NativeInterface.open(); 

     SwingUtilities.invokeLater(new Runnable() { 

       public void run() { 

       WebPageDisplay webDisplay = new WebPageDisplay(); 

       } 

      }); 

    } 
}

這裏是例外。

java.lang.IllegalArgumentException: cannot add to layout: constraint must be a string (or null) 
    at java.awt.BorderLayout.addLayoutComponent(BorderLayout.java:409) 
    at java.awt.Container.addImpl(Container.java:1074) 
    at java.awt.Container.add(Container.java:927) 
    at WebPageDisplay.<init>(PBXPageDisplay.java:35) 
    at WebPageDisplay$1.run(PBXPageDisplay.java:51) 
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209) 
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:677) 
    at java.awt.EventQueue.access$000(EventQueue.java:85) 
    at java.awt.EventQueue$1.run(EventQueue.java:638) 
    at java.awt.EventQueue$1.run(EventQueue.java:636) 
    at java.security.AccessController.doPrivileged(Native Method) 
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87) 
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:647) 
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296) 
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211) 
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201) 
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196) 
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188) 
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

來源

2012-09-23 developer

如果不使用GridBagLayout，則不能使用GridBagConstraints。編譯器告訴你這是沒有道理的，我完全同意。

來源

2012-09-23 05:53:21

iam在代碼禮儀中使用？請建議 – developer

@developer：建議再次 - 不要使用GridBagConstraints，因爲當使用的佈局不是GridBagLayout時，它們沒有任何意義。我不確定這會讓你感到困惑。這是你的所有代碼以上還是它的任何部分借用，因爲這是我能理解你的困惑的唯一途徑。 –

這是唯一的代碼，無非就是那個 – developer

獲取異常：java.lang.IllegalArgumentException：不能添加到佈局：約束必須是一個字符串（或null）

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