Disadvantage of J2ME: these are:
1. Midlet application will never mess up another application on the same device or the device OS itself.
2. Unlike the J2SE, J2ME devices donít have a command prompt.
3. A midlet application invoke in different manner as J2SE because it control by Application Management Software(AMS).
4. AMS interacts with native operations of a Midlet application and controls its life cycle. It is responsible for starting, processing, stoping and destory a Midlets application executions.
5. It have memory is very limited, so operating speed is relatively slow.
6. As J2SE application used data persistence, J2ME is done through the Record Management System (RMS), which operates solely on byte arrays. but it provide a security lake.
7. Unlike J2SE, J2ME device does not support full size keyboard specially alphanumeric sequences.