Java by API/javax.swing.text/Highlighter

Highlighter: addHighlight(int p0, int p1, HighlightPainter p)

 
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;
import javax.swing.text.Highlighter;
import javax.swing.text.JTextComponent;
public class MultiHighlight implements ActionListener {
  private JTextComponent comp;
  private String charsToHighlight;
  public MultiHighlight(JTextComponent c, String chars) {
    comp = c;
    charsToHighlight = chars;
  }
  public void actionPerformed(ActionEvent e) {
    Highlighter h = comp.getHighlighter();
    h.removeAllHighlights();
    String text = comp.getText().toUpperCase();
    for (int j = 0; j < text.length(); j += 1) {
      char ch = text.charAt(j);
      if (charsToHighlight.indexOf(ch) >= 0)
        try {
          h.addHighlight(j, j + 1, DefaultHighlighter.DefaultPainter);
        } catch (BadLocationException ble) {
        }
    }
  }
  public static void main(String args[]) {
    JFrame frame = new JFrame("MultiHighlight");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JTextArea area = new JTextArea(5, 20);
    area.setText("ww\nw.jexp.c\nom");
    frame.getContentPane().add(new JScrollPane(area), BorderLayout.CENTER);
    JButton b = new JButton("Highlight All Vowels");
    b.addActionListener(new MultiHighlight(area, "aeiouAEIOU"));
    frame.getContentPane().add(b, BorderLayout.SOUTH);
    frame.pack();
    frame.setVisible(true);
  }
}

Highlighter: getHighlights()

  
import javax.swing.JTextArea;
import javax.swing.text.Highlighter;
import javax.swing.text.JTextComponent;
public class Main {
  public static void main(String[] argv) throws Exception {
    JTextArea textComp = new JTextArea();
    removeHighlights(textComp);
  }
  public static void removeHighlights(JTextComponent textComp) {
    Highlighter hilite = textComp.getHighlighter();
    Highlighter.Highlight[] hilites = hilite.getHighlights();
    for (int i = 0; i < hilites.length; i++) {
      hilite.removeHighlight(hilites[i]);
    }
  }
}

Highlighter: removeAllHighlights()

 
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;
import javax.swing.text.Highlighter;
import javax.swing.text.JTextComponent;
public class MultiHighlight implements ActionListener {
  private JTextComponent comp;
  private String charsToHighlight;
  public MultiHighlight(JTextComponent c, String chars) {
    comp = c;
    charsToHighlight = chars;
  }
  public void actionPerformed(ActionEvent e) {
    Highlighter h = comp.getHighlighter();
    h.removeAllHighlights();
    String text = comp.getText().toUpperCase();
    for (int j = 0; j < text.length(); j += 1) {
      char ch = text.charAt(j);
      if (charsToHighlight.indexOf(ch) >= 0)
        try {
          h.addHighlight(j, j + 1, DefaultHighlighter.DefaultPainter);
        } catch (BadLocationException ble) {
        }
    }
  }
  public static void main(String args[]) {
    JFrame frame = new JFrame("MultiHighlight");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JTextArea area = new JTextArea(5, 20);
    area.setText("ww\nw.jexp.c\nom");
    frame.getContentPane().add(new JScrollPane(area), BorderLayout.CENTER);
    JButton b = new JButton("Highlight All Vowels");
    b.addActionListener(new MultiHighlight(area, "aeiouAEIOU"));
    frame.getContentPane().add(b, BorderLayout.SOUTH);
    frame.pack();
    frame.setVisible(true);
  }
}

implements Highlighter.HighlightPainter

 
import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Shape;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.text.BadLocationException;
import javax.swing.text.Caret;
import javax.swing.text.DefaultCaret;
import javax.swing.text.Highlighter;
import javax.swing.text.JTextComponent;
public class LineHighlightPainter implements Highlighter.HighlightPainter {
  private void paintLine(Graphics g, Rectangle r, int x2) {
    int ytop = r.y + r.height - 3;
    g.fillRect(r.x, ytop, x2 - r.x, 3);
  }
  public void paint(Graphics g, int p0, int p1, Shape bounds, JTextComponent c) {
    Rectangle r0 = null, r1 = null, rbounds = bounds.getBounds();
    int xmax = rbounds.x + rbounds.width; 
    try { 
      r0 = c.modelToView(p0);
      r1 = c.modelToView(p1);
    } catch (BadLocationException ex) {
      return;
    }
    if ((r0 == null) || (r1 == null))
      return;
    g.setColor(c.getSelectionColor());
    // special case if p0 and p1 are on the same line
    if (r0.y == r1.y) {
      paintLine(g, r0, r1.x);
      return;
    }
    // first line, from p1 to end-of-line
    paintLine(g, r0, xmax);
    // all the full lines in between, if any (assumes that all lines have
    // the same height--not a good assumption with JEditorPane/JTextPane)
    r0.y += r0.height; // move r0 to next line
    r0.x = rbounds.x; // move r0 to left edge
    while (r0.y < r1.y) {
      paintLine(g, r0, xmax);
      r0.y += r0.height; // move r0 to next line
    }
    // last line, from beginning-of-line to p1
    paintLine(g, r0, r1.x);
  }
  public static void main(String args[]) {
    // extend DefaultCaret as an anonymous inner class
    Caret lineHighlightPainterCaret = new DefaultCaret() {
      private Highlighter.HighlightPainter lhp = new LineHighlightPainter();
      // override getSelectionPainter to return the LineHighlightPainter
      protected Highlighter.HighlightPainter getSelectionPainter() {
        return lhp;
      }
    };
    JFrame frame = new JFrame("LineHighlightPainter demo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JTextArea area = new JTextArea(9, 45);
    area.setCaret(lineHighlightPainterCaret);
    area.setLineWrap(true);
    area.setWrapStyleWord(true);
    area.setText("This is the story\nof the hare who\nlost his spectacles.");
    frame.getContentPane().add(new JScrollPane(area), BorderLayout.CENTER);
    frame.pack();
    frame.setVisible(true);
  }
}