Java Reference
In-Depth Information
Listing 15-8.
Program Using a Custom Document Filter
import javax.swing.*;
import javax.swing.text.*;
import java.awt.*;
import java.awt.event.*;
public class RangeSample {
public static void main(String args[]) {
Runnable runner = new Runnable() {
public void run() {
JFrame frame = new JFrame("Range Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridLayout(3, 2));
frame.add(new JLabel("Range: 0-255"));
JTextField textFieldOne = new JTextField();
Document textDocOne = textFieldOne.getDocument();
DocumentFilter filterOne = new IntegerRangeDocumentFilter(0, 255);
((AbstractDocument)textDocOne).setDocumentFilter(filterOne);
frame.add(textFieldOne);
frame.add(new JLabel("Range: -100-100"));
JTextField textFieldTwo = new JTextField();
Document textDocTwo = textFieldTwo.getDocument();
DocumentFilter filterTwo = new IntegerRangeDocumentFilter(-100, 100);
((AbstractDocument)textDocTwo).setDocumentFilter(filterTwo);
frame.add(textFieldTwo);
frame.add(new JLabel("Range: 1000-2000"));
JTextField textFieldThree = new JTextField();
Document textDocThree = textFieldThree.getDocument();
DocumentFilter filterThree = new IntegerRangeDocumentFilter(1000, 2000);
((AbstractDocument)textDocThree).setDocumentFilter(filterThree);
frame.add(textFieldThree);
frame.setSize(250, 150);
frame.setVisible(true);
}
};
EventQueue.invokeLater(runner);
}
}
If you try out this program, you'll notice a couple of interesting issues. The first text field,
with a range of 0 to 255, works fine. You can enter and delete characters at will, as long as the
content is within the range.
