How to open java,python,other files in a JEditorPane

Question

So I was wondering how I can actively change the color of keywords in the java text pane. I understand a document listener is will have to be used, but at the moment it doesn't seem to be working, in fact putting it in the document listener leads to me not being able to properly open a file or color at all. So how can I actively call a method that changes color of keywords in java. This is the code that will search for keywords and it works when I open files, just not actively.

public void findKeyWords(String directory) throws FileNotFoundException
{
  final StyleContext cont = StyleContext.getDefaultStyleContext();
  final AttributeSet jKeyWord = cont.addAttribute(cont.getEmptySet(), 
     StyleConstants.Foreground,Color.RED);
  final AttributeSet jOperator = cont.addAttribute(cont.getEmptySet(), 
     StyleConstants.Foreground,Color.MAGENTA);
  final AttributeSet jtypes = cont.addAttribute(cont.getEmptySet(), 
     StyleConstants.Foreground,Color.CYAN);

     ArrayList<String> words = loadKeyWords(directory);
     for (String line : words)
     {
        searchJava(line,jKeyWord);
     }
     ArrayList<String> operators = loadOperators(directory);
     for (String line : operators)
     {
        searchJava(line, jOperator);
     }
     ArrayList<String> types1 = loadTypes(directory);
     for (String line : types1)
     {
        searchJava(line, jtypes);
     }
}
private ArrayList<String> loadKeyWords(String directory) throws FileNotFoundException
{
  ArrayList<String> javaWords = new ArrayList<String>();
  final String dir = System.getProperty("user.dir");
  File file = new File(dir + "/" + directory + "/keywords.txt");
  Scanner scan = new Scanner(file);
  while(scan.hasNext())
  {
     javaWords.add(scan.next() + " ");
  }
  scan.close();
  return javaWords;
}
private ArrayList<String> loadOperators(String directory) throws FileNotFoundException
{
  ArrayList<String> javaWords = new ArrayList<String>();
  final String dir = System.getProperty("user.dir");
  File file = new File(dir + "/" + directory + "/operators.txt");
  Scanner scan = new Scanner(file);
  while(scan.hasNext())
  {
     javaWords.add(scan.next());
  }
  scan.close();
  return javaWords;
}
private ArrayList<String> loadTypes(String directory) throws FileNotFoundException
{
  ArrayList<String> javaWords = new ArrayList<String>();
  final String dir = System.getProperty("user.dir");
  File file = new File(dir + "/" + directory + "/types.txt");
  Scanner scan = new Scanner(file);
  while(scan.hasNext())
  {
     javaWords.add(" " + scan.next());
  }
  scan.close();
  return javaWords;
}
 public void searchJava(String wordToSearch, AttributeSet javaAttr) 
{ 

  final AttributeSet attr = javaAttr;
  Document text = textArea.getDocument();

  int m;
  int t;
  int total = 0;
  for (String line : textArea.getText().split("\n")) 
  {
     m = line.indexOf(wordToSearch);
     if(m == -1)
     {
        if(isUnix())
        {
        total += line.length() + 1;
        }
        else if(isWindows())
        {
           total += line.length();
        }
        else if(isMac())
        {
           total += line.length() + 1;
        }
        else
        {
           total += line.length() + 1;
        }
        continue;
     }
     try{
     text.remove(total + m, wordToSearch.length());

     text.insertString(total + m, wordToSearch, attr);
     }catch(BadLocationException ex)
     {}
     while(true)
     {
        m = line.indexOf(wordToSearch, m + 1 );

        if (m == -1)
        {
           break;
        }
        try
        {
        text.remove(total + m, wordToSearch.length());

        text.insertString(total + m, wordToSearch, attr);
        }catch(BadLocationException e)
        {
        }
     }
     if(isUnix())
        {
           total += line.length() + 1;

        }
        else if(isWindows())
        {
           total += line.length();
        }
        else if(isMac())
        {
           total += line.length() + 1;
        }
        else
        {
           JOptionPane.showMessageDialog(null, "Eric You Troll" );
           total += line.length() + 1;
        }
  }

}