"Markus" wrote...

Not with a JTextArea.

You should possibly use an JTextPane instead, or an own implementation of
JEditorPane.

Here's a stripped down version of an editor I wrote a couple of years ago...

//---------------------------------------

import javax.swing.*;
import javax.swing.text.*;
import java.awt.*;

class      JSyntaxArea
extends    JEditorPane
{
  StyledDocument document = null;

  MutableAttributeSet defaultSyntax   = new SimpleAttributeSet();
  MutableAttributeSet highlightSyntax = new SimpleAttributeSet();

  public JSyntaxArea ()
  {
     StyledEditorKit editorKit = new StyledEditorKit();
     this.setEditorKit(editorKit);
     document = (StyledDocument) this.getDocument();

     // set colors for the different styles
     StyleConstants.setBackground(highlightSyntax, Color.lightGray);
     StyleConstants.setForeground(highlightSyntax, Color.RED);

     StyleConstants.setBackground(defaultSyntax, Color.WHITE);
     StyleConstants.setForeground(defaultSyntax, Color.BLACK);
  }

  private void setDefault()
  {
     int len = document.getLength();
     String str = null;

     document.setCharacterAttributes(0, len, defaultSyntax, false);
  }

  private void setHighlight (int offset, int len)
  {
     document.setCharacterAttributes(offset, len, highlightSyntax, false);
  }
}

// Note, as it's a stripped down version, it may contain
// some bugs, even though I don't think so...

// Bjorn A

Take a look at JTextComponent.select() and
JTextComponent.setSelectedTextColor().

You _can_ highlight the current line in a JTextArea, but select() is
not the way to do it.  Here's a basic implementation of a current-line
highlighter:

import java.awt.Color;

import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
import javax.swing.text.*;

/*
* Usage: textComp.addCaretListener(new CurrentLineHighlighter());
*/
public class CurrentLineHighlighter implements CaretListener
{
 static final Color DEFAULT_COLOR = new Color(230, 230, 210);

 private Highlighter.HighlightPainter painter;
 private Object highlight;

 public CurrentLineHighlighter()
 {
   this(null);
 }

 public CurrentLineHighlighter(Color highlightColor)
 {
   Color c = highlightColor != null ? highlightColor : DEFAULT_COLOR;
   painter = new DefaultHighlighter.DefaultHighlightPainter(c);
 }

 public void caretUpdate(CaretEvent evt)
 {
   JTextComponent comp = (JTextComponent)evt.getSource();
   if (comp != null && highlight != null)
   {
     comp.getHighlighter().removeHighlight(highlight);
     highlight = null;
   }

   int pos = comp.getCaretPosition();
   Element elem = Utilities.getParagraphElement(comp, pos);
   int start = elem.getStartOffset();
   int end = elem.getEndOffset();
   try
   {
     highlight = comp.getHighlighter().addHighlight(start, end,
painter);
   }
   catch (BadLocationException ex)
   {
     ex.printStackTrace();
   }
 }
}