How to highlight a single word in a JTextArea

Question

I want to read in text the user inputs and then highlight a specific word and return it to the user. I am able to read in the text and give it back to the user, but I cant figure out how to highlight a single word. How can I highlight a single word in a JTextArea using java swing?

Answer 1

Use the DefaultHighlighter that comes with your JTextArea. For e.g.,

import java.awt.Color;
import javax.swing.*;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;
import javax.swing.text.Highlighter;
import javax.swing.text.Highlighter.HighlightPainter;

public class Foo001 {
   public static void main(String[] args) throws BadLocationException {
      
      JTextArea textArea = new JTextArea(10, 30);
       
      String text = "hello world. How are you?";
      
      textArea.setText(text);
      
      Highlighter highlighter = textArea.getHighlighter();
      HighlightPainter painter = 
             new DefaultHighlighter.DefaultHighlightPainter(Color.pink);
      int p0 = text.indexOf("world");
      int p1 = p0 + "world".length();
      highlighter.addHighlight(p0, p1, painter );
      
      JOptionPane.showMessageDialog(null, new JScrollPane(textArea));          
   }
}

addHighlight()

Parameters:

• p0 - the beginning of the range >= 0
• p1 - the end of the range >= p0
• p - the painter to use for the actual highlighting

Returns:

an object that refers to the highlight

Throws:

BadLocationException - for an invalid range specification