I have just been given a 6310i phone and have started to explore the Java capabilities of this unit. If I go to the Nokia Software Market WAP site and attempt to download an application such as "Racket Game" the application starts to download but then I get an "Invalid File" error message. Does anyone have any ideas as to what might be causing this?
This message seems common on the 6310i when trying to install Java MIDlets. At least I kept on getting it when loading ones onto our device. A couple of things might cause it.
There might be a MIDlet-Jar-Size parameter in the manifest file, even though there shouldn't be, and it specifies a size that is different from the actual jar size. This also happens if you try and deploy the file onto the handset using a data cable and the Nokia J2ME Toolkit. If the MIDlet-Jar-Size value in the JAD file is not exactly the same as the actual jar size, deployment will fail.
Also, if you're using the deployment tool, if any of the fields in the JAD file don't match exactly the fields in the manifest file within the JAR, you'll get an error. Fields like the MIDlet-Vendor and MIDlet-Version must match exactly.
The jar file is bigger than 30k. The 6310i seems to have a hardcoded limit of 30k for jar files, bigger than this and the download/install will fail.
As to exactly why the file from the Nokia download site fails I don't know. Certainly it should be checked by Nokia first, but the sorts of problems I've mentioned are easy to miss when producing MIDlet jar files. The 3610i seems particularly sensitive to the information too, so they may have got something wrong.
LongSteve already gave an interesting reply (and he did it half a year ago ) but it seems that I found another thing that may be causing this behaviour. I download a game using "Application Installer" from PC Suite I got on a CD with the phone and the DLR-3P cable.
When I try to start freshly downloaded application while the cable is still plugged into the phone, I get the "invalid file" message. When I disconnect the cable first, the application works great (if it was designed for Nokia, of course - it's good to check it with the emulator first).