Short answer: Impossible.
Long answer explaining alternatives:
There is no way to convert MATLAB code automatically to JAVA code, such a Software does not exist. There are several ways to deploy MATLAB code to be called from JAVA. If a MATLAB installation is available on the target system, possibilities are listed in this question. If MATLAB is not available on your target system, possibilities are listed in this answer. Note that the answers working with OCTAVE probably don't work with your GUI.
Not having MATLAB available on the target system and requiring GUI components, the MATLAB Builder JA probably the only choice for a automatic conversion to jar (not to java code). It is also a very expensive choice.