Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Shape;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.JTextPane;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
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;
import javax.swing.text.LayeredHighlighter;
import javax.swing.text.Position;
import javax.swing.text.View;

public class Main {
    public static void main(String[] args) {
        JFrame f = new JFrame();
        JPanel panel = new JPanel();
        JTextPane textPane = new JTextPane();
        JTextField tf = new JTextField("is");
        String word = "";
        Highlighter highlighter = new UnderlineHighlighter(null);

        textPane.setHighlighter(highlighter);
        textPane.setText("This is a test");
        panel.setLayout(new BorderLayout());
        panel.add(new JLabel("Enter word, then press ENTER key: "), "West");
        panel.add(tf, "Center");

        final WordSearcher searcher = new WordSearcher(textPane);
        tf.addActionListener(e -> {
            String w = tf.getText().trim();
            int offset = searcher.search(w);
            if (offset == -1) {
                return;
            }
            try {
                textPane.scrollRectToVisible(textPane.modelToView(offset));
            } catch (BadLocationException ex) {
            }

        });
        textPane.getDocument().addDocumentListener(new DocumentListener() {
            @Override
            public void insertUpdate(DocumentEvent evt) {
                searcher.search(word);
            }

            @Override
            public void removeUpdate(DocumentEvent evt) {
                searcher.search(word);
            }

            @Override
            public void changedUpdate(DocumentEvent evt) {
            }
        });
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(panel, "South");
        f.add(new JScrollPane(textPane), "Center");
        f.setSize(400, 400);
        f.setVisible(true);
    }
}

class WordSearcher {

    protected JTextComponent comp;
    protected Highlighter.HighlightPainter painter;

    public WordSearcher(JTextComponent comp) {
        this.comp = comp;
        this.painter = new UnderlineHighlightPainter(Color.red);
    }

    public int search(String word) {
        int firstOffset = -1;
        Highlighter highlighter = comp.getHighlighter();
        Highlighter.Highlight[] highlights = highlighter.getHighlights();
        for (int i = 0; i < highlights.length; i++) {
            Highlighter.Highlight h = highlights[i];
            if (h.getPainter() instanceof UnderlineHighlightPainter) {
                highlighter.removeHighlight(h);
            }
        }
        if (word == null || word.equals("")) {
            return -1;
        }
        String content = null;
        try {
            Document d = comp.getDocument();
            content = d.getText(0, d.getLength()).toLowerCase();
        } catch (BadLocationException e) {
            return -1;
        }
        word = word.toLowerCase();
        int lastIndex = 0;
        int wordSize = word.length();
        while ((lastIndex = content.indexOf(word, lastIndex)) != -1) {
            int endIndex = lastIndex + wordSize;
            try {
                highlighter.addHighlight(lastIndex, endIndex, painter);
            } catch (BadLocationException e) {
            }
            if (firstOffset == -1) {
                firstOffset = lastIndex;
            }
            lastIndex = endIndex;
        }
        return firstOffset;
    }
}

class UnderlineHighlighter extends DefaultHighlighter {

    protected static final Highlighter.HighlightPainter sharedPainter = new UnderlineHighlightPainter(null);
    protected Highlighter.HighlightPainter painter;

    public UnderlineHighlighter(Color c) {
        painter = (c == null ? sharedPainter : new UnderlineHighlightPainter(c));
    }

    public Object addHighlight(int p0, int p1) throws BadLocationException {
        return addHighlight(p0, p1, painter);
    }

    @Override
    public void setDrawsLayeredHighlights(boolean newValue) {
        super.setDrawsLayeredHighlights(true);
    }

}

class UnderlineHighlightPainter extends LayeredHighlighter.LayerPainter {
    protected Color color;

    public UnderlineHighlightPainter(Color c) {
        color = c;
    }

    @Override
    public void paint(Graphics g, int offs0, int offs1, Shape bounds, JTextComponent c) {
    }

    @Override
    public Shape paintLayer(Graphics g, int offs0, int offs1, Shape bounds, JTextComponent c, View view) {
        g.setColor(color == null ? c.getSelectionColor() : color);
        Rectangle rect = null;
        if (offs0 == view.getStartOffset() && offs1 == view.getEndOffset()) {
            if (bounds instanceof Rectangle) {
                rect = (Rectangle) bounds;
            } else {
                rect = bounds.getBounds();
            }
        } else {
            try {
                Shape shape = view.modelToView(offs0, Position.Bias.Forward, offs1, Position.Bias.Backward, bounds);
                rect = (shape instanceof Rectangle) ? (Rectangle) shape : shape.getBounds();
            } catch (BadLocationException e) {
                return null;
            }
        }
        FontMetrics fm = c.getFontMetrics(c.getFont());
        int baseline = rect.y + rect.height - fm.getDescent() + 1;
        g.drawLine(rect.x, baseline, rect.x + rect.width, baseline);
        g.drawLine(rect.x, baseline + 1, rect.x + rect.width, baseline + 1);
        return rect;
    }
}