I found 7650's JVM had a serious bug.When I read a big block
of data from RMS, using RecordStore's method getRecord,
JVM alloc new memory from system, but not from the free memory JVM had managed. So if I do the RMS operation for many times, the memory used by JVM increased fast, although the memory actually used by program didn't change. And at last it lead to "memory full" error.
The bug exists in both emulator and real 7650.
I guess the bug of Image and Resource also come from it...
I will do more experiment.