JTextPane Syntax-Highlighting

Question

I'm currently working on a really simple IDE meant for C programming in Java. And by simple I mean it has minor code-guessing (Similar to Eclipse), some minor auto-completion (Once again, think Eclipse), and some syntax highlighting. I have just about everything figured out and roughed-out (i.e. working, but not pretty or efficient), except I'm having some trouble with proper Syntax highlighting.

What I mean by that is; in my code JFrame, I put in a JTextPane so I could use different fonts, bold, un-bold, italicize, and add different text colors with relative ease. I have a key-listener hooked up to this JTextPane, and on each space-bar press, it grabs what you just wrote, runs it through an "if" statement-tree to see if the word you wrote is a keyword. If you did, it attempts to highlight (or not) what you just wrote. However, there are some cases where I need it to change color before I hit a space-bar (such as a comment, or a #define statement). No problem, right? Just add another "if" statement to detect if that key has been pressed, and if it has, change the font color. Well, that's what I attempted to do, however it isn't working. It is really messing with my mind seeing as I use the EXACT same code to change colors that I do with the space-bar press (which works just dandy).

Sorry if that doesn't make much sense, I'll be happy to explain a bit more if it's required. I also removed as much un-necessary code as possible, to try to shorten it down.

Thank you very much for your time!

~Cent

SSCCE:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;

import javax.swing.JFrame;
import javax.swing.JTextPane;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.StyleConstants;
import javax.swing.text.StyledDocument;

public class Main implements Runnable
{
private static final long serialVersionUID = 1L;
private static final int WIDTH = 800;
private static final int HEIGHT = 600;
private static final String NAME = "";
private JFrame frame;
private JTextPane textPane = new JTextPane();
private int keysPressed = -1; /* Keys pressed */
private ArrayList<Integer> keyCode = new ArrayList<Integer>(); /* List of our keyCodes */

public void run()
{
    frame = new JFrame(NAME);
    frame.setPreferredSize(new Dimension(WIDTH, HEIGHT));
    frame.setMinimumSize(new Dimension(WIDTH, HEIGHT));
    frame.setMaximumSize(new Dimension(WIDTH, HEIGHT));
    frame.setResizable(false);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    frame.setLayout(new BorderLayout()); 
    frame.add(textPane, BorderLayout.CENTER);
    textPane.setPreferredSize(new Dimension(WIDTH, HEIGHT));
    textPane.setEditable(true);
    textPane.addKeyListener(new KeyListener(){
                @Override 
                public void keyPressed(KeyEvent e) 
                {
                     int previousPos; /* Previous position of the caret */
                     int length; /* Length of our grabbed string */

                     int currentPos; /* Current position of the caret */

                     String text; /* The entire text of the JTextPane */
                     String subText; /* Our sub-string-text we're using */
                     String subTextP; /* Our sub-string-text plus one character*/

                     boolean first = true; /* Be default, it's the first letter */

                     StyledDocument doc = textPane.getStyledDocument(); 
                     SimpleAttributeSet sas = new SimpleAttributeSet(); /* So we can set bold, and such */

                     keyCode.add(new Integer(e.getKeyCode())); /* The key pressed */
                     keysPressed++;
                     currentPos = textPane.getCaretPosition(); /* The current position of the caret */

                     text = textPane.getText(); /* Grabbing the text on the text pane */
                     previousPos = text.lastIndexOf(" ", currentPos); /* Getting the last position of a space */
                     if(previousPos <= 0) /* If the position if before or equal to 0 */ 
                     {
                         previousPos = 0; /* Then the position is 0 */
                     }
                     length = currentPos - previousPos; /* The length of the string we're messing with, is between the two positions */
                     subText = text.substring(previousPos, currentPos); /* Grabbing the string between our two positions */
                     if(first) /* If this is the first letter, or insert */
                     {
                         if(keyCode.contains(KeyEvent.VK_SHIFT))
                         {
                             first = true;
                             subTextP = text.substring(0, 0); /* Then we want to grab it, at 0, 0 */
                         }
                         else
                         {
                             subTextP = text.substring(0, 0); /* Then we want to grab it, at 0, 0 */
                             first = false; /* it's no longer the first */
                         }
                     }
                     else /* If it isn't */
                     {
                         subTextP = text.substring(previousPos + 1, currentPos); /* Then we want to grab the usual */
                     }
                     subText = subText.replaceAll("[\\n\\t\\r]", ""); /* Getting rid of all the tabs and newlines */
                     subTextP = subTextP.replaceAll("[\\n\\t\\r]", ""); /*Getting rid of all the tabs and new lines */

                     if(keyCode.contains(KeyEvent.VK_3)) 
                     {
                         if(keyCode.contains(KeyEvent.VK_SHIFT)) 
                         {
                             System.out.println("Number sign hit!");                                 
                             StyleConstants.setForeground(sas, Color.GREEN); /* Anything following a number sign will be green */
                             doc.setCharacterAttributes(previousPos, length, sas, false);  /* Turning it green */
                         }
                     }
                     if(keyCode.contains(KeyEvent.VK_SPACE)) /* If a space has been hit! */
                     {
                         /* This is were we'll do all text coloring and such */
                         if(subText.equals(" if") || subText.equals("if") || subTextP.equals("if")) /* All things to be bolded */
                         {
                             StyleConstants.setForeground(sas, Color.GRAY); /* All of these statements will be gray... */
                             StyleConstants.setBold(sas, true); /* ... and bold */
                             doc.setCharacterAttributes(previousPos, length, sas, false); /* Making them so! */
                             StyleConstants.setBold(sas, false); /* We don't want these attributes to remain... */
                             StyleConstants.setForeground(sas, Color.black); /* ... So we're removing them. */
                         }
                     }
                }

                public void keyReleased(KeyEvent e) 
                {
                    for(int i = keysPressed; i >= 0; i--) /* For loop to remove all keyPresses from our list */
                    {
                        keyCode.remove(i); /* Removing the specified keyPress */
                    }
                    keysPressed = -1; /* Because the first index is 0, and we want to add one to keysPressed, we need to start below 0 */
                }

                @Override
                public void keyTyped(KeyEvent arg0) {
                }
    });
    frame.pack(); 
    frame.setVisible(true);
}

public void start()
{
    new Thread(this).start();
}

public final static void main(String args[])
{
    new Main().start();
}

}

EDIT:

To reproduce the issue, run the code provided above. In the textPane, type in the word "if" (no quotes) and then hit the space-bar. The word should be bolded now, and a gray color. Now, try typing in a "#" (no quotes) after it, (space in-between) and hit space, or any other key; nothing happens. However, the system should print out "Number sign hit!" once you do input a "#", meaning the code is in fact still reachable. Also note that I use the same code (besides changing the colors) for the "#" as I do for the "if". Hope that helps you guys understand the problem a bit more.

Answer 1

First of all it's not correct to use KeyListener here.

Use KeyBindings or DocumentListener or DocumentFilter instead (or even replace the Document with own extension to override insertString() and remove() methods). You should change the highlight not only after space typing but also when somebody removes chars from the mid of the keyword.

Please post SSCCE to show real problem and provide steps to reproduce actual behaviour and describe desired behaviour.