Compare two strings and highlight the mismatch wherever found

Question

I want to compare two strings and highlight the word(s) wherever there is a mismatch.

The code I have written has the following 2 issues :

1 . Wherever ther

Answer 1

Instead of trying to find the tokens in the Document, which might appear multiple times (as you've provide no context by which you can determine exactly which token you are talking about), you could simply compare the two Documents more directly, maintaining the current position offset from which you are making the comparison...

int max = Math.min(doc1.getLength(), doc2.getLength());
int startPos = 0;
try {
    for (int pos = 0; pos < max; pos++) {

        if (doc1.getText(pos, 1).equals(" ")) {

            int endPos = pos;
            String parent = doc1.getText(startPos, endPos - startPos);
            String child = doc2.getText(startPos, endPos - startPos);
            if (!parent.equals(child)) {

                highlight(field, startPos, endPos);
                highlight(area, startPos, endPos);

            }

            startPos = endPos + 1;

        }

    }
} catch (BadLocationException exp) {
    exp.printStackTrace();
}

(note, probably should be highlighting any text that is beyond the end of the other document, but you can figure that out ;))

import java.awt.Color;
import java.awt.GridLayout;
import java.lang.reflect.InvocationTargetException;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;
import javax.swing.text.Document;
import javax.swing.text.Highlighter;
import javax.swing.text.JTextComponent;

public class HighlightCheck {

    private String Retext1 = "Extreme programming is one approach of agile software development which emphasizes on frequent releases on short development cycles which are called time boxes. This result in reducing the costs spend for changes, by having multiple short development cycles, rather than one long one. Extreme programming includes pair-wise programming (for code review, unit testing).Also it avoids implementing features which are not included in the current time box, so the schedule creep can be minimized.";
    private String Retext2 = "Extreme programming is one approach of agile software development which emphasizes on frequent releases in short development cycles which are called time boxes. This result in reducing the costs spend for changes, by having multiple short development cycles, rather than one long one. Extreme programming includes pair-wise programming (for code review, unit testing).Also it avoids implementing features which are not included in the current time box, so the schedule creep can be minimized.";

    private Highlighter.HighlightPainter myHighlightPainter = new MyHighlightPainter(Color.red);

    public static void main(String args[]) {

        try {

            SwingUtilities.invokeAndWait(new Runnable() {

                public void run() {
                    new HighlightCheck().createAndShowGUI();
                }
            });

        } catch (InterruptedException ex) {
            ex.printStackTrace();

        } catch (InvocationTargetException ex) {
            ex.printStackTrace();
        }
    }

    public void createAndShowGUI() {

        JFrame frame = new JFrame("Error-Highlighter");
        frame.setLayout(new GridLayout(2, 1));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JTextArea field = new JTextArea(5, 50);
        field.setText(Retext2);
        field.setLineWrap(true);
        field.setWrapStyleWord(true);
        field.setEditable(false);

        frame.add(new JScrollPane(field));

        JTextArea area = new JTextArea(5, 50);
        area.setText(Retext1);
        area.setLineWrap(true);
        area.setWrapStyleWord(true);
        area.setEditable(false);

        Document doc1 = field.getDocument();
        Document doc2 = area.getDocument();

        int max = Math.min(doc1.getLength(), doc2.getLength());
        int startPos = 0;
        try {
            for (int pos = 0; pos < max; pos++) {

                if (doc1.getText(pos, 1).equals(" ")) {

                    int endPos = pos;
                    String parent = doc1.getText(startPos, endPos - startPos);
                    String child = doc2.getText(startPos, endPos - startPos);
                    if (!parent.equals(child)) {

                        highlight(field, startPos, endPos);
                        highlight(area, startPos, endPos);

                    }

                    startPos = endPos + 1;

                }

            }
        } catch (BadLocationException exp) {
            exp.printStackTrace();
        }

        frame.getContentPane().add(new JScrollPane(area));
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public void highlight(JTextComponent textComp, int startPos, int endPos) throws BadLocationException {

        Highlighter hilite = textComp.getHighlighter();
        hilite.addHighlight(startPos, endPos, myHighlightPainter);

    }

    class MyHighlightPainter extends DefaultHighlighter.DefaultHighlightPainter {

        public MyHighlightPainter(Color color) {

            super(color);

        }
    }
}