Thread: Syntax Highlighting in Editor

Here is the original code I found on StackOverFlow. It highlights some specific words in a JTextPane.

import javax.swing.*;
import java.awt.*;
import javax.swing.text.*;
 
public class ColorChangeWhileTyping extends JFrame{
 
 
 
    private int findLastNonWordChar (String text, int index) {
        while (--index >= 0) {
            if (String.valueOf(text.charAt(index)).matches("\\W")) {
                break;
            }
        }
        return index;
    }
 
    private int findFirstNonWordChar (String text, int index) {
        while (index < text.length()) {
            if (String.valueOf(text.charAt(index)).matches("\\W")) {
                break;
            }
            index++;
        }
        return index;
    }
 
    public ColorChangeWhileTyping () {
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setSize(400, 400);
        setLocationRelativeTo(null);
 
        final StyleContext cont = StyleContext.getDefaultStyleContext();
        final AttributeSet attr = cont.addAttribute(cont.getEmptySet(), StyleConstants.Foreground, Color.RED);
        final AttributeSet attrBlack = cont.addAttribute(cont.getEmptySet(), StyleConstants.Foreground, Color.BLACK);
        DefaultStyledDocument doc = new DefaultStyledDocument() {
            public void insertString (int offset, String str, AttributeSet a) throws BadLocationException {
                super.insertString(offset, str, a);
 
                String text = getText(0, getLength());
                int before = findLastNonWordChar(text, offset);
                if (before < 0) before = 0;
                int after = findFirstNonWordChar(text, offset + str.length());
                int wordL = before;
                int wordR = before;
 
                while (wordR <= after) {
                    if (wordR == after || String.valueOf(text.charAt(wordR)).matches("\\W")) {
                        if (text.substring(wordL, wordR).matches("(\\W)*(private|public|protected)"))
                            setCharacterAttributes(wordL, wordR - wordL, attr, false);
                        else
                            setCharacterAttributes(wordL, wordR - wordL, attrBlack, false);
                        wordL = wordR;
                    }
                    wordR++;
                }
            }
 
            public void remove (int offs, int len) throws BadLocationException {
                super.remove(offs, len);
 
                String text = getText(0, getLength());
 
                int before = findLastNonWordChar(text, offs);
                if (before < 0) before = 0;
                int after = findFirstNonWordChar(text, offs);
 
                if (text.substring(before, after).matches("(\\W)*(private|public|protected)")) {
                    setCharacterAttributes(before, after - before, attr, false);
                } else {
                    setCharacterAttributes(before, after - before, attrBlack, false);
                }
            }
        };
        JTextPane txt = new JTextPane(doc);
        txt.setText("public class Hi {}");
        add(new JScrollPane(txt));
        setVisible(true);
    }
 
    public static void main (String args[]) {
        new ColorChangeWhileTyping();
    }
 
}

I Modified it a little to suit my purpose as the orginal code was highlighting text with only one colour.
I want to highlight different words with different colour.
Here is the modified code

 
import java.awt.Color;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultStyledDocument;
import javax.swing.text.StyleConstants;
import javax.swing.text.StyleContext;
 
public class KeyWordCheck extends JFrame {
 
    List section;
    JTextPane textArea;
 
    String red = "section";
    String blue = ".bss|.data|.text";
    String mainString = "section|.bss|.data|.text";
 
    private int findLastNonWordChar(String text, int index) {
        while (--index >= 0) {
            if (String.valueOf(text.charAt(index)).matches(mainString)) {
                break;
            }
        }
        return index;
    }
 
    private int findFirstNonWordChar(String text, int index) {
        while (index < text.length()) {
            if (String.valueOf(text.charAt(index)).matches(mainString)) {
                break;
            }
            index++;
        }
        return index;
    }
 
    JTextPane KeyWorPane;
 
    public KeyWordCheck() {
 
         setDefaultCloseOperation(EXIT_ON_CLOSE);
        setSize(400, 400);
        setLocationRelativeTo(null);
 
        final StyleContext cont = StyleContext.getDefaultStyleContext();
 
        final AttributeSet attrRed = cont.addAttribute(cont.getEmptySet(), StyleConstants.Foreground, Color.RED);
 
        final AttributeSet attrBlack = cont.addAttribute(cont.getEmptySet(), StyleConstants.Foreground, Color.BLACK);
 
        final AttributeSet attrBlue = cont.addAttribute(cont.getEmptySet(), StyleConstants.Foreground, Color.BLUE);
 
        DefaultStyledDocument doc = new DefaultStyledDocument() {
            public void insertString(int offset, String str, AttributeSet a) throws BadLocationException {
                super.insertString(offset, str, a);
 
                String text = getText(0, getLength());
                int before = findLastNonWordChar(text, offset);
                if (before < 0) {
                    before = 0;
                }
                int after = findFirstNonWordChar(text, offset + str.length());
                int wordL = before;
                int wordR = before;
 
                while (wordR <= after) {
                    if (wordR == after || String.valueOf(text.charAt(wordR)).matches(mainString)) {
                        if (text.substring(wordL, wordR).matches(red)) {
                            setCharacterAttributes(wordL, wordR - wordL, attrRed, false);
                        }
                        else if (text.substring(wordL, wordR).matches(blue)) {
                            setCharacterAttributes(wordL, wordR - wordL, attrBlue, false);
                        }
                        else {
                            setCharacterAttributes(wordL, wordR - wordL, attrBlack, false);
                        }
                        wordL = wordR;
                    }
                    wordR++;
                }
            }
 
            public void remove(int offs, int len) throws BadLocationException {
                super.remove(offs, len);
 
                String text = getText(0, getLength());
 
                int before = findLastNonWordChar(text, offs);
                if (before < 0) {
                    before = 0;
                }
                int after = findFirstNonWordChar(text, offs);
 
                if (text.substring(before, after).matches(red)) {
                    setCharacterAttributes(before, after - before, attrRed, false);
                }
                 else if (text.substring(before, after).matches(blue)) {
                    setCharacterAttributes(before, after - before, attrBlue, false);
                } else {
                    setCharacterAttributes(before, after - before, attrBlack, false);
                }
            }
 
        }; 
        textArea = new JTextPane(doc);
 
 
        add(new JScrollPane(textArea));
        setVisible(true);
    }
public static void main(String args[])
{
    new KeyWordCheck();
}
}

I dont know for some reason it doesnt work correctly. The colour goes away after I press Space to write the next word
Please Help!!!

Well I figured it out. The Main Reason it was not working was that i have removed the "\\W" used for comparison by Word