How do you seriously entertain this 'idea' that 'Java' is about 'cross platform' and 'portability'? It is NOT. How can it be since that would involve having to port a Java VM to every one of those devices?
The only thing that is portable is 'C' - hence why it once stood for 'Portable Assembler'. Even C++is not portable enough from that perspective.
Anybody saying that any higher-level language is about 'portability' frankly doesn't have a clue what they are actually talking about. I'll never be able to run a Java program on an Xbox1 or a Nintendo Gamecube (because those systems are 'deserted') - but I am able to do that just fine with a C program. There goes your 'portability' argument right out of the window without me even trying - because I actually practice what I preach.
Google has much of their server side code in Java.
I know a lot of FLOSStards love Google though - why I cannot profess to know - it beats the other people I talk to as well. But you will find out soon enough just how much of a 'friend' they are to your cause - don't worry. Mindless acolytes always get confronted with the 'truth' in the end, and that's when a lot of butthurt will be felt.