Using a buffer between input and a JTextField

Question

Instead of using a document filter, or a FormatMask I am trying something different. Here is the requirements. Have a JTextField only accept/have one character of input allowed into it at a time, the only allowed input is numbers 1-9 think of the game Sudoku, all other input is invalid and should not be allowed. I tried handleing this with both of the above ideas and still kept getting error beeps for backspace and delete keys when using focus on the JTextField.

So I thought why not have something as a buffer that can ignore all input data I did not want to accept here is my solution.

import java.awt.Component;
import java.awt.GridLayout;
import javax.swing.*;   
import java.awt.event.*;

public class MaskField 
{    
    JFrame thisframe;
    JPanel jPanel1 = new JPanel();
    JTextField jTextField1 = new JTextField();

    public MaskField()
    {       
        thisframe = new JFrame();
        jTextField1.addFocusListener(new FocusListener(){
           @Override
           public void focusLost(FocusEvent e){}
           @Override
           public void focusGained(FocusEvent e)
           {
               JTextField thisfield = (JTextField)e.getSource();
               thisfield.getParent().requestFocus();               
           }            
        });
        jPanel1.addKeyListener(new KeyAdapter()
        {
            @Override
            public void keyReleased(KeyEvent e){}
            @Override
            public void keyTyped(KeyEvent e){}
            @Override
            public void keyPressed(KeyEvent e) 
            {   
                JPanel thispanel = (JPanel)e.getSource();
                Component[] complist = thispanel.getComponents();
                JTextField thisfield = (JTextField)complist[0];
                text = thisfield.getText();                
                if(Character.isDigit(e.getKeyChar()) && !"0".equals(Character.toString(e.getKeyChar())))
                {
                    thisfield.setText(Character.toString(e.getKeyChar()));                        
                }
                if(e.getKeyCode() == 127 || e.getKeyCode() == 8)
                    thisfield.setText("");
            }
        });
        jPanel1.setLayout(new GridLayout(1,1));
        jTextField1.setText("");
        jPanel1.add(jTextField1);
        thisframe.add(jPanel1);        
        thisframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        thisframe.setVisible(true);
        thisframe.pack();
    }
    public static void main(String args[])
    {
        new MaskField();
    }
}

I would greatly appreciate any different ideas about how to handle this because getting and changing the JTextField data is so verbose.