We help IT Professionals succeed at work.

We've partnered with Certified Experts, Carl Webster and Richard Faulkner, to bring you two Citrix podcasts. Learn about 2020 trends and get answers to your biggest Citrix questions!Listen Now

x

Fixed size TextArea/TextField possible?

bjoern
bjoern asked
on
Medium Priority
610 Views
Last Modified: 2008-03-10
I'm making a series of applets which all contain input areas for dates (year, month, day). These areas should be 4,2 and 2 characters wide respectively. When I do this however, the text you write in the area just scrolls if there is more than the width of the area. Isn't it possible to make an input area with a fixed size, e.g. where you can write 2 characters and ONLY 2 characters?
Comment
Watch Question

Its possible, but you are going to have to subclass either textField or textArea.

An eisier alternative would be to catch keyboard events using keyDoun(Event evt, int key), maintain a character count for each field and just append the charachter via appendText().

Which method would you be intrested in?

Author

Commented:
I would prefer to subclass textField as this is "cleaner".
If you (jpk) could supply with a way to do this, the 50 points are yours :)
This should do the trick for you:

Warning: Untested code.


public class FixedTextField extends TextField {
   int count = 0;
   int  max = 0;

   FixedTextField( String theString ) {
      super( theString );
   }
 
   FixedTextField( String theString, int MaxSize ) {
      max = MaxSize;
      super( theString );
   }

// keyDown count the input
   public boolean keyDown( Event event,int key ) {

       if (max == 0){ // if the edit cell is of unlimited size
          super.keyDown( event,key );
          return true;
      }
      if (count < max){
         if (key != 8) // If not backspace
            count++;
         else
             count--;
         auper.keyDown( event,key );
      }
      return( true );
   }

}

Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts

Author

Commented:
I can see what the idea is, the only problem is that the keyDown event doesn't print the pressed key in the textfield! is super.keyDown() the right way to do this or what?

Maybe you could try it yourself. If this little problem gets solved the points are yours jpk.
You are right, it does not!

It seems that TextField does not process its own events!?!

So we have to override event.

Here is a class that works:

import java.awt.*;

//Define a custom TextField class that can respond to events.
//  Note that this class extends TextField.
class TF extends TextField{

  int maxCount = 5;
  int count = 0;       
  TF(String inString, int MaxCount){
     setText(inString);
     maxCount = MaxCount;
  }//end constructor

  //The following event handler method handles events at the
  // component level as opposed to the container level.
  public boolean handleEvent(Event evObj){
 
    switch(evObj.id){
      case Event.KEY_PRESS :
        if (count < maxCount){
             char[] c = new char[1];
             c[0]= (char) evObj.key;
             String s = new String(c);
             setText(getText() + s);
             count++;
          }
          break;
      default : //catch and display all other event types here
          break;
    }//end switch
    return super.handleEvent(evObj);
  }//end handleEvent() in class TF
 
}//end class TF
//===================================================================

And folloing is a sample app that uses it:

import java.awt.*;


public class Event05 extends Frame{

  public Event05(){
    TF myTextField = new TF("", 5);//instantiate custom TextField object
    add ("Center",myTextField);
    myTextField.setEditable(false);//make it non-editable

    resize(300,50);//set frame size    
   }//end constructor

  //Create and show the frame object
  public static void main(String[] args){
    Event05 displayWindow = new Event05(); //instantiate obj of this type
    displayWindow.show();//display the frame
  }//end main
 
 
  public boolean handleEvent(Event evObj){
    //Terminate program if user closes the window
    if(evObj.id == Event.WINDOW_DESTROY) System.exit(0);
    return super.handleEvent(evObj);                      
  }//end handleEvent()
 
}//end class Event05



Note: Don't chage the points value. It was fun, but If the points were worth money (and not just brag points :-) ) I would have asked you to cancel my previous answer, increae the point bvalue to about 200 and then give you this answer.

Learned a bit though.

Author

Commented:
Thanks, sorry about the additional work, but at least you learned something too :)
Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

OR

Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.