import java.awt.Toolkit;
import java.awt.event.KeyEvent;
import java.awt.event.KeyAdapter;
//this class for monitoring keyTyped
public class KeyAction extends KeyAdapter{
public void keyTyped(KeyEvent e){
char ch=e.getKeyChar();
String detectStr;
//only 0 to 9 backspace or delete key character can be input
if(ch>0x2f&&ch<0x3a||ch==0x08||ch==0x10||ch==0x2e){
}else{
Toolkit.getDefaultToolkit().beep();
e.consume();//for consuming the listener
}