Highlight text in JTextArea

/**
*
* @author Monirul Molla
*/
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import javax.swing.*;
import javax.swing.text.*;
import javax.swing.event.*;
import javax.swing.GroupLayout.*;

public class TextFieldDemo extends JFrame
implements DocumentListener {

private JTextField entry;
private JLabel jLabel1;
private JScrollPane jScrollPane1;
private JLabel status;
private JTextArea textArea;

final static Color HILIT_COLOR = Color.LIGHT_GRAY;
final static Color ERROR_COLOR = Color.PINK;
final static String CANCEL_ACTION = "cancel-search";

final Color entryBg;
final Highlighter hilit;
final Highlighter.HighlightPainter painter;


public TextFieldDemo() {
initComponents();

InputStream in = getClass().getResourceAsStream("content.txt");
try {
textArea.read(new InputStreamReader(in), null);
} catch (IOException e) {
e.printStackTrace();
}

hilit = new DefaultHighlighter();
painter = new DefaultHighlighter.DefaultHighlightPainter(HILIT_COLOR);
textArea.setHighlighter(hilit);

entryBg = entry.getBackground();
entry.getDocument().addDocumentListener(this);

InputMap im = entry.getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
ActionMap am = entry.getActionMap();
im.put(KeyStroke.getKeyStroke("ESCAPE"), CANCEL_ACTION);
am.put(CANCEL_ACTION, new CancelAction());
}

/** This method is called from within the constructor to
* initialize the form.
*/

private void initComponents() {
entry = new JTextField();
textArea = new JTextArea();
status = new JLabel();
jLabel1 = new JLabel();

setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
setTitle("TextFieldDemo");

textArea.setColumns(20);
textArea.setLineWrap(true);
textArea.setRows(5);
textArea.setWrapStyleWord(true);
textArea.setEditable(false);
jScrollPane1 = new JScrollPane(textArea);

jLabel1.setText("Enter text to search:");

GroupLayout layout = new GroupLayout(getContentPane());
getContentPane().setLayout(layout);

//Create a parallel group for the horizontal axis
ParallelGroup hGroup = layout.createParallelGroup(GroupLayout.Alignment.LEADING);

//Create a sequential and a parallel groups
SequentialGroup h1 = layout.createSequentialGroup();
ParallelGroup h2 = layout.createParallelGroup(GroupLayout.Alignment.TRAILING);

//Add a container gap to the sequential group h1
h1.addContainerGap();

//Add a scroll pane and a label to the parallel group h2
h2.addComponent(jScrollPane1, GroupLayout.Alignment.LEADING, GroupLayout.DEFAULT_SIZE, 450, Short.MAX_VALUE);
h2.addComponent(status, GroupLayout.Alignment.LEADING, GroupLayout.DEFAULT_SIZE, 450, Short.MAX_VALUE);

//Create a sequential group h3
SequentialGroup h3 = layout.createSequentialGroup();
h3.addComponent(jLabel1);
h3.addPreferredGap(LayoutStyle.ComponentPlacement.RELATED);
h3.addComponent(entry, GroupLayout.DEFAULT_SIZE, 321, Short.MAX_VALUE);

//Add the group h3 to the group h2
h2.addGroup(h3);
//Add the group h2 to the group h1
h1.addGroup(h2);

h1.addContainerGap();

//Add the group h1 to the hGroup
hGroup.addGroup(GroupLayout.Alignment.TRAILING, h1);
//Create the horizontal group
layout.setHorizontalGroup(hGroup);


//Create a parallel group for the vertical axis
ParallelGroup vGroup = layout.createParallelGroup(GroupLayout.Alignment.LEADING);
//Create a sequential group v1
SequentialGroup v1 = layout.createSequentialGroup();
//Add a container gap to the sequential group v1
v1.addContainerGap();
//Create a parallel group v2
ParallelGroup v2 = layout.createParallelGroup(GroupLayout.Alignment.BASELINE);
v2.addComponent(jLabel1);
v2.addComponent(entry, GroupLayout.PREFERRED_SIZE, GroupLayout.DEFAULT_SIZE, GroupLayout.PREFERRED_SIZE);
//Add the group v2 tp the group v1
v1.addGroup(v2);
v1.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED);
v1.addComponent(jScrollPane1, GroupLayout.DEFAULT_SIZE, 233, Short.MAX_VALUE);
v1.addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED);
v1.addComponent(status);
v1.addContainerGap();

//Add the group v1 to the group vGroup
vGroup.addGroup(v1);
//Create the vertical group
layout.setVerticalGroup(vGroup);
pack();
}

public void search() {
hilit.removeAllHighlights();

String s = entry.getText();
if (s.length() <= 0) {
message("Nothing to search");
return;
}

String content = textArea.getText();
int index = content.indexOf(s, 0);
if (index >= 0) { // match found
try {
int end = index + s.length();
hilit.addHighlight(index, end, painter);
textArea.setCaretPosition(end);
entry.setBackground(entryBg);
message("'" + s + "' found. Press ESC to end search");
} catch (BadLocationException e) {
e.printStackTrace();
}
} else {
entry.setBackground(ERROR_COLOR);
message("'" + s + "' not found. Press ESC to start a new search");
}
}

void message(String msg) {
status.setText(msg);
}



// DocumentListener methods

public void insertUpdate(DocumentEvent ev) {
search();
}

public void removeUpdate(DocumentEvent ev) {
search();
}

public void changedUpdate(DocumentEvent ev) {
}

class CancelAction extends AbstractAction {
public void actionPerformed(ActionEvent ev) {
hilit.removeAllHighlights();
entry.setText("");
entry.setBackground(entryBg);
}
}


public static void main(String args[]) {
//Schedule a job for the event dispatch thread:
//creating and showing this application's GUI.
SwingUtilities.invokeLater(new Runnable() {
public void run() {
//Turn off metal's use of bold fonts
UIManager.put("swing.boldMetal", Boolean.FALSE);
new TextFieldDemo().setVisible(true);
}
});
}
}