Enthuware

This will not compile because Java does not allow operator overloading for user defined classes.

Can you explain this with a example??

Operator overloading allows you to define new behavior for existing operators such a +, - etc. You can do that in C/C++, but not in Java. You can see examples in c/c++ https://en.wikibooks.org/wiki/C%2B%2B_P ... verloading
but not in Java because it is not allowed.