Java Swing JTextField - Only Numbers
I am making a small java Swing Applet that converts temperatures: TempConvert.java
Here is my code:
package swing;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
/** Celcius to Fahrenheit Converter
* @version 1.0
* @author Oliver Ni
*/
public class TempConvert extends JApplet{
JLabel result;
JRadioButton ctof;
JRadioButton ftoc;
JTextField deg;
JLabel degLab;
JButton convert;
public void convert() {
if (ctof.isSelected() == true) {
result.setText("<html><br>" + Integer.toString(Integer.parseInt(deg.getText()) * 9 / 5 + 32) + "<sup>o</sup> F</html>");
} else if (ftoc.isSelected() == true) {
result.setText("<html><br>" + Integer.toString((Integer.parseInt(deg.getText()) - 32) * 5 / 9) + "<sup>o</sup> C</html>");
} else {
result.setText("<html><br>Error.</html>");
}
}
public void makeApplet() {
setLayout(new FlowLayout());
ctof = new JRadioButton("Celcius to Fahrenheit");
ftoc = new JRadioButton("Fahrenheit to Celcius");
convert = new JButton("Convert");
result = new JLabel("");
ButtonGroup group = new ButtonGroup();
group.add(ctof);
group.add(ftoc);
deg = new JTextField(10);
degLab = new JLabel("<html><sup>o</sup></html>");
convert.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent ae) {
convert();
}
});
add(ctof);
add(ftoc);
add(deg);
add(degLab);
add(convert);
add(result);
}
public void init() {
try {
SwingUtilities.invokeAndWait(new Runnable() {
public void run() {
makeApplet();
}
});
} catch(Exception e) {
System.out.println("Error loading because " + e);
}
}
}
I want to restrict the JTextField deg to only integers. Is there any way I can do that?
Any help would be appreciated!
Answer
"I want to restrict the JTextField deg to only integers."
Try this. Use a Document Filter
((AbstractDocument) deg.getDocument()).setDocumentFilter(new DocumentFilter() {
Pattern regEx = Pattern.compile("\\d+");
@Override
public void replace(FilterBypass fb, int offset, int length, String text, AttributeSet attrs) throws BadLocationException {
Matcher matcher = regEx.matcher(text);
if (!matcher.matches()) {
return;
}
super.replace(fb, offset, length, text, attrs);
}
});