import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;
class NonNumericDocument extends PlainDocument {
@Override
public void insertString(int offs, String str, AttributeSet a)
throws BadLocationException {
if (str == null) {
return;
}
char[] arr = str.toCharArray();
for (int i = 0; i < arr.length; i++) {
if (Character.isDigit(arr[i]) || !Character.isLetter(arr[i])) {
return;
}
}
super.insertString(offs, new String(str), a);
}
}
public class Main extends JFrame {
JTextField tf;
public void prepareAndShowGUI() {
tf = new JTextField(30);
tf.setDocument(new NonNumericDocument());
getContentPane().add(tf, BorderLayout.NORTH);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
pack();
setVisible(true);
}
public static void main(String[] args) {
Main tFrame = new Main();
tFrame.prepareAndShowGUI();
}
}
【jtextfield】
