Converting .exe(c++ made) to mobile executable .jar.?

There is no converter that will convert C++ code to Java code, as far as I'm aware of. .jar to .exe converters work by turning the Java file into an executable file that you can launch as an exe, which can overcome some limitations that are encountered by certain users, but will not convert C++ code to Java code. Short answer: You can't. If you want to program Java for mobiles, learn to program Java for mobiles!