import  javax.swing.JTextField;
 import  javax.swing.text.*;

 public   class  TextLengthLimitTextField  extends  JTextField
{
   protected   int  textLengthLimit = - 1 ;

   public  TextLengthLimitTextField()
  {
     super ();
  }

   public  TextLengthLimitTextField(String text)
  {
     super (text);
  }

   public   int  getTextLengthLimit()
  {
     return  textLengthLimit;
  }

   public   void  setTextLengthLimit( int  textLengthLimit)
  {
     this .textLengthLimit = textLengthLimit;
  }

   protected  Document createDefaultModel()
  {
     return   new  TextLengthLimitDocument();
  }

   protected   class  TextLengthLimitDocument  extends  PlainDocument
  {
     public   void  insertString( int  offs, String str, AttributeSet a)  throws  BadLocationException
    {
       if  (str ==  null )  return ;
      String insertStr = str;
       if  (textLengthLimit >  0 )
      {
         int  curLength =  this .getLength();
         if  (curLength >= textLengthLimit)  return ;
         int  insertLength = insertStr.length();
         if  ((curLength + insertLength) > textLengthLimit)
          insertStr = insertStr.substring( 0 , (textLengthLimit - curLength -  1 ));
      }
       super .insertString(offs, insertStr, a);
    }
  }
}