"AWT-EventQueue-0" java.lang.NullPointerException exception

Question

I want to highlight the patterns that are present in my string. For this purpose I have created a database of patterns and stored them in an array. Now I want these patterns to be highlighted in jtextpane and with different colors and I have used if else condition for this purpose that will highlight the patterns with different colors based on the strings that are stored in other arraylist but I am having following exception .

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.text.DefaultHighlighter.paint(DefaultHighlighter.java:72)
at javax.swing.plaf.basic.BasicTextUI.paintSafely(BasicTextUI.java:731)
at javax.swing.plaf.basic.BasicTextUI.paint(BasicTextUI.java:881)
at javax.swing.plaf.synth.SynthEditorPaneUI.paint(SynthEditorPaneUI.java:180)
at javax.swing.plaf.synth.SynthEditorPaneUI.update(SynthEditorPaneUI.java:168)
at javax.swing.JComponent.paintComponent(JComponent.java:778)
at javax.swing.JComponent.paint(JComponent.java:1054)
at javax.swing.JComponent.paintToOffscreen(JComponent.java:5219)

at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1452)
at javax.swing.RepaintManager.paint(RepaintManager.java:1249)
at javax.swing.JComponent._paintImmediately(JComponent.java:5167)
at javax.swing.JComponent.paintImmediately(JComponent.java:4978)
at javax.swing.RepaintManager$3.run(RepaintManager.java:808)
at javax.swing.RepaintManager$3.run(RepaintManager.java:796)
at java.security.AccessController.doPrivileged(Native Method)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:796)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:769)
at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:718)
at javax.swing.RepaintManager.access$1100(RepaintManager.java:62)
at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1677)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:733)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:694)
at java.awt.EventQueue$3.run(EventQueue.java:692)
at java.security.AccessController.doPrivileged(Native Method)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:703)
atjava.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

This is my code.

  jTextPane2.setText(seq);

  for (int i = 0; i < mot.size(); i++) {
    if (mot.get(i) == "set") {
      myHighlightPainter = new MyHighlightPainter(Color.red);
    } else if (mot.get(i) == "get") {
      myHighlightPainter = new MyHighlightPainter(Color.green);
    }
    highlight(jTextPane2, pat.get(i));
  }// patterns arraylist
}

public void highlight(JTextComponent textComp, String pattern) {

  try {
    Highlighter hilite = textComp.getHighlighter();
    Document doc = textComp.getDocument();
    String text = doc.getText(0, doc.getLength());
    int pos = 0;

    // Search for pattern
    // see I have updated now its not case sensitive
    while ((pos = text.toUpperCase().indexOf(pattern.toUpperCase(), pos)) >= 0) {
      // Create highlighter using private painter and apply around pattern
      hilite.addHighlight(pos, pos + pattern.length(), myHighlightPainter);
      pos += pattern.length();
    }
  } catch (BadLocationException e) {
  }
}

How can I solve this problem?

How can I solve this problem? -- by posting an SSCCE with hardcoded text for JTextPanes Document in local variable — mKorbel
– mKorbel, Commented Oct 28, 2013 at 13:18
mot.get(i) == "set" -> This is wrong. Use mot.get(i).equals("set") instead (but it will not solve this problem). — Arnaud Denoyelle
– Arnaud Denoyelle, Commented Oct 28, 2013 at 13:43
This is the string which is passed in setText method.seq="aset"; — Sarah
– Sarah, Commented Oct 28, 2013 at 13:44

mKorbel · Accepted Answer · 2013-10-28 13:28:54Z

1

Your myHighlightPainter is null in some cases.

DefaultHighlighter line#72

            Highlighter.HighlightPainter p = info.getPainter();
      -->   p.paint(g, info.getStartOffset(), info.getEndOffset(),a, component);

edited Oct 28, 2013 at 13:28

mKorbel

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answered Oct 28, 2013 at 13:24

StanislavL

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Sarah Over a year ago

How can I avoid that problem?

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