JTextField problem

[Tony Shi]

Hi,
I wnat to create a JTextField that accepts 0-9 only. I tried the following code,

 
  public void insertString(int offs, String str, AttributeSet a)
        throws BadLocationException {
    if ((getLength() + str.length()) <= maxCharacters && (str.hashCode()>47 && str.hashCode()<=57))
      super.insertString(offs, str, a);
    else
      Toolkit.getDefaultToolkit().beep();   
  }

it worked, but jTextField.selectAll() and jTextField.setText("String") stopped working. I can't seem to figure out the reason. Can someone please help?
Thanks a lot!

[Jason O' Regan]

You should implement a Document that only accepts numeric values,
by subclassing the javax.swing.text.PlainDocument class and overriding the insertString method there. Then add this Document to the JTextField using the setDocument method.