Twitter

Follow us on Twitter

Recent Comments

  • msanabria: You have to copy logg4j library in the application server libraries
  • Matthew: What if it is the catalina.yyyy-mm-dd.log that we wish to stop? logrotate seems t handle the catalina.out...
  • Namrata: Hey, This solution is worked well but when try to use same at google app engine, I’m not able to do....
  • Jonathan: Thank you, this worked perfectly! I appreciate you posting this.
  • Sanjay Biswal: Good Question Answer.

Tags
Feb 07

How to limit number of characters in JTextField?

java, swing Add comments

To restrict the number of characters that the user can enter into a text field can be achieved by either using a JFormattedTextField or using a custom Document with any JTextComponent.

To implement this using a JFormattedTextFiled is simply a matter of specifying the appropriate MaskFormatter to meet your requiremenets.

JTextField field = new JFormattedTextField(new MaskFormatter("***"));

The following class gives an example of how a custom Document can be implemented for use in any text component.

public class FixedSizeDocument extends PlainDocument
{
   private int max = 10;

   public FixedSizeDocument(int max)
   {
        this.max = max;
   } 

   @Override
   public void insertString(int offs, String str, AttributeSet a)
      throws BadLocationException
   {
      // check string being inserted does not exceed max length

      if (getLength()+str.length()>max)
      {
         // If it does, then truncate it

         str = str.substring(0, max - getLength());
      }
      super.insertString(offs, str, a);
   }
}

You can then use this class with your JTextField for example using the following

field.setDocument(new FixedSizeDocument(5));

written by objects \\ tags: , , , , ,


13 Responses to “How to limit number of characters in JTextField?”

  1. Mr Swing Says:
    September 18th, 2009 at 12:19 am

    Hi. This was just great. Much better and easier than suggestion at Sun and other Java sites.

  2. objects Says:
    September 18th, 2009 at 1:36 pm

    Glad you liked it, thanks for the feedback

  3. Blue Says:
    October 15th, 2009 at 5:50 am

    Mr Swing is right. I tried this solution and it worked great!!! This is the best solution that I found on the web and I’ve been searching for days already and I always ended up being linked to those complicated solutions on different websites. Thanks a lot!!! I really really appreciate it

  4. Ken Says:
    June 3rd, 2010 at 1:47 am

    Best solution on the web. Far simpler than the many other “solutions” I found. Thanks.

  5. objects Says:
    June 3rd, 2010 at 8:30 am

    Thanks, glad you found it useful.

  6. Eric Cute Says:
    June 22nd, 2010 at 12:15 pm

    Wow. This solution really worked and very simple to understand for java beginners like me. Thank a lot!

  7. objects Says:
    June 22nd, 2010 at 12:18 pm

    Thanks Eric.

  8. Anu Says:
    October 22nd, 2010 at 12:54 am

    Great job

  9. dan Says:
    December 9th, 2010 at 9:32 pm

    really easy, I like it

  10. Una Says:
    October 5th, 2011 at 8:28 pm

    Set up a keytyped event on the textfield

    if (jTextField1.getText().length()>=2){

    evt.consume();

    }

  11. objects Says:
    October 5th, 2011 at 8:33 pm

    Using a KeyListener will be problematic for cut and paste, and if the text field change is not caused by typing (eg. if its value is programatically changed)

  12. vanb Says:
    October 7th, 2011 at 3:31 pm

    Thanks….
    This solution helped me and it works fine.

  13. prakash Says:
    December 14th, 2011 at 6:22 pm

    thanks for the post, helped me..

Leave a Reply