[Skipper_Joe]

Here is the sample:

import net.rim.device.api.ui.UiApplication;
import net.rim.device.api.ui.text.TextFilter;
import net.rim.device.api.ui.component.BasicEditField;
import net.rim.device.api.ui.container.MainScreen;

public class TFilterApp extends UiApplication
{
    private static class Form extends MainScreen
    {
        public Form()
        {
            setTitle("Test app");
            BasicEditField field = new BasicEditField("Enter data:", "");
            field.setFilter(new TextFilter()
            {

                public char convert(char c, int i)
                {
                    return c;  // don't convert anything here
                }

                public boolean validate(char c)
                {
                    return (Character.isDigit(c) || Character.isLowerCase(c) || Character.isUpperCase(c));
                }
            });
            add(field);
        }
    }


    TFilterApp()
    {
        pushScreen(new Form());
    }

    public static void main(String[] args)
    {
        TFilterApp app = new TFilterApp();
        app.enterEventDispatcher();
    }
}