What are the advantages of using Virtual Machine compilation (eg. JVM) over natively compiled languages?

Question

I\'ve heard that the advantage of java is that people can write code, compile it for the JVM, and run it anywhere. Each person just needs a JVM app for their platform.

Answer 1

Guess you are talking of porting issues. Indeed JVM is what is spoken of in popular literature, that Java eliminates the need for code porting is a shade more subtle.

You don't have to look too far. A small industry of Windows to UNIX code porting developers [and vice versa] exist for this precise reason. Want examples? How about things like those near, far pointers in C? Or using __declspec(dllexport) to create a Windows specific dll while gcc will have none of this and you need -shared option?

One of the most difficult scenario was with doing C++ based GUI in particular before QT came into existence. Loads of GUI is still done on .NET, legacy code is on MFC and for Linux/UNIX a lot of legacy code is in XWindows. Java is a godsend in such cases -- most stuff will work without re-inventing the wheel across platforms.