NullPointerException in Applet

**JosAH** · Aug 15 '07, 08:22 AM

Originally posted by r035198x

@Jos, why would he get a nullpointer at that line? I'd expect the nullpointer to occur somewhere else, most likely outside the createGUI method.

I don't know but I suspect the code is different from what we see here. A different
version mayhap ... that local variable definitely is a nono.

kind regards,

Jos

**JosAH** · Aug 15 '07, 08:24 AM

Originally posted by r035198x

Commenting out lines of code that give errors does not neccessarily remove the errors.

That's the good ol' "amputation strategy". The old Romans already did that:
does your leg hurt? *Chop!* now it doesn't hurt anymore.

Nowadays people sometimes mistake Occam's Razor for the "amputation strategy" ;-)

kind regards,

Jos

**teenIce** · Aug 15 '07, 08:33 AM

I had try both of the method and still it give error.Let me explain what I'm trying to do and sorry if I had you guys confuse with my code.. :). The code that I copy just now is from open source code and it is create a gui for the application. The code is already a GUI so I create an applet to access the function that create the GUI and launch it using an applet so I can pass my parameters to certain function in the main code.

Now I'll paste the main code that create gui

Code:

public class Main  implements ActionListener {

  private static final String OPTIONS_BUTTON = "Options...";
  
  private JTextArea textArea = null;
  private JTextPane resultArea = null;
  private JComboBox langBox = null;
 
  private Map<Language, ConfigurationDialog> configDialogs = new HashMap<Language, ConfigurationDialog>();

   public Main() {
  }

  public void createAndShowGUI(String inputText) {
    JFrame frame = new JFrame("Grammar Check Tool");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    textArea = new JTextArea(inputText);
    // TODO: wrong line number is displayed for lines that are wrapped automatically:
    textArea.setLineWrap(true);
    textArea.setWrapStyleWord(true);
    resultArea = new JTextPane();
    resultArea.setContentType("text/html");
    resultArea.setText("Results will appear here");
    JLabel label = new JLabel("Please type or paste text to check in the top area");
    JButton button = new JButton("Check text");
    button.setMnemonic('c'); 
    button.addActionListener(this);

    JButton configButton = new JButton(OPTIONS_BUTTON);
    configButton.setMnemonic('o'); 
    configButton.addActionListener(this);

    JPanel panel = new JPanel();
    panel.setLayout(new GridBagLayout());
    GridBagConstraints buttonCons = new GridBagConstraints();
    buttonCons.gridx = 0;
    buttonCons.gridy = 0;
    panel.add(button, buttonCons);
    buttonCons.gridx = 1;
    buttonCons.gridy = 0;
    panel.add(new JLabel("  "), buttonCons);
    buttonCons.gridx = 2;
    buttonCons.gridy = 0;
    langBox = new JComboBox();
 	/*for (Language lang : Language.LANGUAGES) {
      if (lang != Language.DEMO) {
        langBox.addItem(lang);
      }
    }*/
    //panel.add(langBox, buttonCons);
    buttonCons.gridx = 3;
    buttonCons.gridy = 0;
    buttonCons.insets = new Insets(0, 10, 0, 0);
    //panel.add(configButton, buttonCons);

    Container contentPane = frame.getContentPane();
    GridBagLayout gridLayout = new GridBagLayout();
    contentPane.setLayout(gridLayout);
    GridBagConstraints cons = new GridBagConstraints();
    cons.fill = GridBagConstraints.BOTH;
    cons.weightx = 10.0f;
    cons.weighty = 10.0f;
    cons.gridx = 0;
    cons.gridy = 0;
    contentPane.add(new JScrollPane(textArea), cons);
    cons.gridy = 1;
    cons.weighty = 5.0f;
    contentPane.add(new JScrollPane(resultArea), cons);

    cons.fill = GridBagConstraints.NONE;
    cons.gridx = 0;
    cons.gridy = 2;
    cons.weighty = 0.0f;
    cons.insets = new Insets(3,3,3,3);
    //cons.fill = GridBagConstraints.NONE;
    contentPane.add(label, cons);
    cons.gridy = 3;
    contentPane.add(panel, cons);
    
    frame.pack();
    frame.setSize(600, 600);
    frame.setVisible(true);
  }
  
  public void actionPerformed(ActionEvent e) {
     String langName = "English";	
     Language language = Language.getLanguageForName(langName);
     ConfigurationDialog configDialog = null;
    if (configDialogs.containsKey(language)) {
      configDialog = (ConfigurationDialog)configDialogs.get(language);
    } else {
      configDialog = new ConfigurationDialog(null, false);
      configDialogs.put(language, configDialog);
	 // JOptionPane.showMessageDialog(null,"test"); 
    }
    JLanguageTool langTool;
    try {
      langTool = new JLanguageTool(language, configDialog.getMotherTongue());
      langTool.activateDefaultPatternRules();
      langTool.activateDefaultFalseFriendRules();
      Set disabledRules = configDialog.getDisabledRuleIds();
      if (disabledRules != null) {
        for (Iterator iter = disabledRules.iterator(); iter.hasNext();) {
          String ruleId = (String) iter.next();
          langTool.disableRule(ruleId);
        }
      }
    } catch (IOException ioe) {
      throw new RuntimeException(ioe);
    } catch (ParserConfigurationException ex) {
      throw new RuntimeException(ex);
    } catch (SAXException ex) {
      throw new RuntimeException(ex);
    }
    if (e.getActionCommand().equals(OPTIONS_BUTTON)) {
      List rules = langTool.getAllRules();
      configDialog.show(rules);
    } else {
      if (textArea.getText().trim().equals("")) {
        textArea.setText("Please insert text to check here");
      } else {
        StringBuffer sb = new StringBuffer();
        resultArea.setText("Starting check...<br>\n");
        resultArea.repaint(); // FIXME: why doesn't this work?
        //TODO: resultArea.setCursor(new Cursor(Cursor.WAIT_CURSOR)); 
        sb.append("Starting check in " +langName+ "...<br>\n");
        int matches = 0;
        try {
          matches = checkText(langTool, textArea.getText(), sb);
        } catch (Exception ex) {
          sb.append("<br><br><b><font color=\"red\">" + ex.toString() + "<br>");
          StackTraceElement[] elements = ex.getStackTrace();
          for (StackTraceElement element : elements) {
            sb.append(element + "<br>");
          }
          sb.append("</font></b><br>");
          ex.printStackTrace();
        }
        sb.append("Check done. " +matches+ " potential problems found<br>\n");
        resultArea.setText(sb.toString());
        resultArea.setCaretPosition(0);
      }
    }
  }
    
  public int checkText(JLanguageTool langTool, String text, StringBuffer sb) throws IOException {
    long startTime = System.currentTimeMillis();
    List ruleMatches = langTool.check(text);
    long startTimeMatching = System.currentTimeMillis();
    int i = 0;
    for (Iterator iter = ruleMatches.iterator(); iter.hasNext();) {
      RuleMatch match = (RuleMatch) iter.next();
      sb.append("<br>\n<b>" +(i+1)+ ". Line " + (match.getLine() + 1) + ", column " + match.getColumn()
          + "</b><br>\n");
      String msg = match.getMessage();
      msg = msg.replaceAll("<suggestion>", "<b>");
      msg = msg.replaceAll("</suggestion>", "</b>");
      msg = msg.replaceAll("<old>", "<b>");
      msg = msg.replaceAll("</old>", "</b>");
      sb.append("<b>Message:</b> " + msg + "<br>\n");
      sb.append("<b>Context:</b> " + Tools.getContext(match.getFromPos(), match.getToPos(), text));
      sb.append("<br>\n");
      i++;
    }
    long endTime = System.currentTimeMillis();
    sb.append("<br>\nTime: " + (endTime - startTime) + "ms (including "
        + (endTime - startTimeMatching) + "ms for rule matching)<br>\n");
    return ruleMatches.size();
  }

  public void openGui (String input) {
  	/*final Main prg = new Main();
    prg.createAndShowGUI("They is around. ");*/
	JOptionPane.showMessageDialog(null,"open"); 
	createAndShowGUI(input);
  }
 
  
}

I hope you can help me to understand this code too.I really appreciate it.Thanks guys....

**teenIce** · Aug 15 '07, 08:41 AM

And this is the trace when i try to launch the GUI with my applet.

Code:

Java Plug-in 1.6.0_02
Using JRE version 1.6.0_02 Java HotSpot(TM) Client VM
User home directory = C:\Documents and Settings\Administrator
network: Loading user-defined proxy configuration ...
network: Done.
network: Loading proxy configuration from Internet Explorer ...
network: Done.
network: Loading direct proxy configuration ...
network: Done.
network: Proxy Configuration: No proxy


----------------------------------------------------
c:   clear console window
f:   finalize objects on finalization queue
g:   garbage collect
h:   display this help message
l:   dump classloader list
m:   print memory usage
o:   trigger logging
p:   reload proxy configuration
q:   hide console
r:   reload policy configuration
s:   dump system and deployment properties
t:   dump thread list
v:   dump thread stack
x:   clear classloader cache
0-5: set trace level to <n>
----------------------------------------------------

liveconnect: Invoking JS method: document
liveconnect: Invoking JS method: URL
basic: Referencing classloader: sun.plugin.ClassLoaderInfo@12498b5, refcount=1
basic: Added progress listener: sun.plugin.util.GrayBoxPainter@f5da06
basic: Loading applet ...
basic: Initializing applet ...
basic: Starting applet ...
basic: completed perf rollup
liveconnect: Invoking method: public void test.check(java.lang.String)
liveconnect: Needs conversion: java.lang.String --> java.lang.String
java.lang.NullPointerException
	at java.util.Hashtable.put(Unknown Source)
	at javax.swing.JEditorPane.registerEditorKitForContentType(Unknown Source)
	at javax.swing.JEditorPane.registerEditorKitForContentType(Unknown Source)
	at javax.swing.JEditorPane.loadDefaultKitsIfNecessary(Unknown Source)
	at javax.swing.JEditorPane.getKitTypeRegistry(Unknown Source)
	at javax.swing.JEditorPane.getEditorKitClassNameForContentType(Unknown Source)
	at javax.swing.JTextPane.<init>(Unknown Source)
	at mypack.Main.createAndShowGUI(main.java:84)
	at mypack.Main.openGui(main.java:238)
	at test.check(test.java:27)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at sun.plugin.javascript.JSInvoke.invoke(Unknown Source)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at sun.plugin.javascript.JSClassLoader.invoke(Unknown Source)
	at sun.plugin.com.MethodDispatcher.invoke(Unknown Source)
	at sun.plugin.com.DispatchImpl.invokeImpl(Unknown Source)
	at sun.plugin.com.DispatchImpl$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.plugin.com.DispatchImpl.invoke(Unknown Source)
java.lang.Exception: java.lang.NullPointerException
	at sun.plugin.com.DispatchImpl.invokeImpl(Unknown Source)
	at sun.plugin.com.DispatchImpl$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.plugin.com.DispatchImpl.invoke(Unknown Source)

**Gregory** · Aug 30 '07, 04:45 AM

any luck in resolving your problem? I have the same exception trace inside of my applet too...

thanks,
Gregory

**teenIce** · Aug 30 '07, 07:46 AM

Originally posted by Gregory

any luck in resolving your problem? I have the same exception trace inside of my applet too...

thanks,
Gregory

No, I just don't use the interface anymore. Sorry I'm not so helpful too.

**Nepomuk** · Aug 30 '07, 08:36 AM

Originally posted by Gregory

any luck in resolving your problem? I have the same exception trace inside of my applet too...

thanks,
Gregory

Hi Gregory! Welcome to TSDN!

We might be able to help you nevertheless if you post the relevant code and (even if it's the same) your stack trace.

Greetings,
nepomuk