Listing 1:
import com.sun.java.swing.*;
import com.sun.java.swing.text.*;
import java.util.*;
import java.awt.*;

public class CodeDocument extends DefaultStyledDocument{
  private String word = "";
  private SimpleAttributeSet bold = new SimpleAttributeSet();
  private SimpleAttributeSet normal = new SimpleAttributeSet();
  private int currentPos = 0;
  private Vector keywords = new Vector();

  public CodeDocument() {
   //set the bold attribute
   StyleConstants.setBold(bold, true);
  }

  private void checkForKeyword(){
    int offs = this.currentPos;
    Element element = this.getParagraphElement(offs);
    String elementText = "";
    try{
      //this gets our chuck of current text for the element we’re on
      elementText = this.getText(element.getStartOffset(),                   element.getEndOffset() - element.getStartOffset());
    }
    catch(Exception ex){
      //whoops!
      System.out.println("no text");
    }
    int strLen = elementText.length();
    if (strLen == 0) {return;}
    int i = 0;

    if (element.getStartOffset() > 0){
      //translates backward if neccessary
      offs = offs - element.getStartOffset();
    }
    if ((offs >= 0) && (offs <= strLen-1)){
      i = offs;
      while (i >0){
      //the while loop walks back until we hit a delimiter
        i--;
        char charAt = elementText.charAt(i);
        if ((charAt == ' ') | (i == 0) | (charAt =='(') | (charAt ==')') |
            (charAt == '{') | (charAt == '}')){ //if i == 0 then we're at the begininng
          if(i != 0){
            i++;
          }
          word = elementText.substring(i, offs);//skip the period

          String s = word.trim().toLowerCase();
          //this is what actually checks for a matching keyword
          if (keywords.contains(s)){
            try{
              //remove the old word and formatting
              this.remove(currentPos - word.length(), word.length());
              /*replace it with the same word, but new formatting
              *we MUST call the super class insertString method here, otherwise we
              *would end up in an infinite loop !!!!!*/
              super.insertString(currentPos - word.length(), word, bold);
            }
            catch (Exception ex){
              ex.printStackTrace();
            }
          }
          break;
        }
      }
    }
  }

  public void insertString(int offs,
                          String str,
                          AttributeSet a) throws BadLocationException{
    if (offs < 0){
      return;
    }
    currentPos = offs;
    char strChar;
    super.insertString(offs, str, normal);

    int strLen = str.length();
    if (strLen > 1){

    }
    else{
      strChar = str.charAt(0);

      switch (strChar){
        case ('{'):case ('}'):case (' '): case('\n'):
        case ('('):case (')'):case (';'):case ('.'):{
          checkForKeyword();
          wordStart = offs;
        }
        break;
      }//end switch
    }
  }

  public Vector getKeywords(){
    return this.keywords;
  }

  public void setKeywords(Vector aKeywordList){
    if (aKeywordList != null){
      this.keywords = aKeywordList;
    }
  }
}