maziar navahan:
the mcu is not game tool!

An MCU is a very versatile tool indeed, and I'm sure that very large volumes of them are to be found within games products!

See my earlier post: just like "Embedded System," the term "MCU" covers a whole spectrum of devices from 4-bit to 32-bit and beyond.

In many cases, the software development cost can exceed the hardware parts cost in a product; in such cases, the efficiency of the software development process becomes of great importance. This is where the likes of Jave can be particularly useful.

BTW: Note that it is possible to "compile" Java to native binary - so it doesn't have to be interpreted (known as "Ahead Of Time" or AOT translation)

But Java on an 8051 does still sound somewhat unlikely to me. ;-)