java-melcdui

Where did lcdui go, in JME SDK 3.0+?

I want to write a tiny "hello world" J2ME MIDlet. In a sample like this one, classes in javax.microedition.lcdui.* are used for display output. When I try to compile it in Eclipse, I get the error,

The import javax.microedition.lcdui cannot be resolved

I've installed JME SDK 3.4, and I'm able to run MIDlets that don't import javax.microedition.lcdui.*. I read somewhere that lcdui can be obtained from the wireless toolkit; and Oracle says that the wireless toolkit has been integrated into JME SDK as of 3.0+.

So why can't Eclipse find it?

Solution

  • OK, I think I know the answer now.

    I got back to the JME SDK 3.4 documentation page on Using Sample projects, and created and ran an instance of UIDemo. It uses lcdui classes, but it runs flawlessly - no errors about inability to resolve javax.microedition.lcdui.*.

    The difference appears to be that the working sample uses different libraries than the one I tried at first. The first one uses org.elipse.mtj.JavaMEContainer/Oracle Java(TM) Platform Micro Edition SDK 3.4/IMPNGDevice1, while the one that works uses org.elipse.mtj.JavaMEContainer/Oracle Java(TM) Platform Micro Edition SDK 3.4/JavaMEPhone1. They contain different sets of jars, e.g. the working one contains midp_2.1.jar, while the earlier one has impng_1.0.jar.

    A follow-up question might be, why doesn't IMP-NG have lcdui in it? Well, those who pay attention to what they're doing will have read that

    This JSR [for IMP-NG] will define a J2ME profile targeting embedded networked devices that wish to support a Java runtime environment similar to the Mobile Information Device Profile (MIDP) version 2.0, but that do not provide the graphical display capabilities required by MIDP 2.0.

    The Information Module Profile - Next Generation (IMP-NG) will be a strict subset of MIDP 2.0, where at least the APIs relating to GUI functionality (the LCDUI) are removed. Functionality not already present in MIDP 2.0 is not anticipated or desired. "

    The next question might be, why did I end up selecting IMP-NG when I was going through the tutorial... when I really do want a MIDlet that does something graphically? But I'm not sure I care, now that it's working.