import  javax.swing.*;
 import  javax.swing.text.*;
 
 public   class  LimitedTextArea  extends  JFrame {
 
     public  LimitedTextArea() {
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        JTextArea text =  new  JTextArea( 5 ,  40 );
        // Set the customized Document on the text area. Only allow
        // a maximum of ten characters:
        text.setDocument( new  LimitedDocument( 10 ));
        getContentPane().add( new  JScrollPane( text ));
        pack();
        setLocationRelativeTo( null );
    }
    
     public   static   void  main(String[] args) {
         new  LimitedTextArea().setVisible(true);
    }
    
    
    // Document that only allows a certain number of characters
     class  LimitedDocument  extends  PlainDocument {
 
         private   int  maxLength;
        
         public  LimitedDocument( int  maxLength) {
             this .maxLength = maxLength;
        }
 
        // This method is overriden from the super class. It will be called when
        // you are trying to insert text in your text component (by typing
        // or pasting).
         public   void  insertString( int  offs, String str, AttributeSet a)  throws  BadLocationException {
             int  currentLength = getLength();
             if ( currentLength >= maxLength ) {
                // There's not room for more characters. Return.
                 return ;
            }
             if ( currentLength + str.length() > maxLength ) {
                // All of the characters we are trying to insert will not fit.
                // We must trim the string.
                str = str.substring( 0 , maxLength - currentLength);
            }
            // Insert the text:
             super .insertString(offs, str, a);
        }
    }
    
}