This is just a simple theoretical question out of curiosity. I have always been like a java fan boy. But one thing makes me wonder why java does not provide mechanism for creating objects on the stack ? Wouldn't it be more efficient if i could just create small Point(int x,int y ) object on the stack instead of the heap like creating a structure on C# . Is there any special security reason behind this restriction in java ? :)
The strategy here is that instead of leaking this decision into the language, Java lets the JVM/Hotspot/JIT/runtime decide where and how it wants to allocate memory.
There is research going on to use "escape analysis" to figure out what objects don't actually need to go onto the heap and stack-allocate them instead. I am not sure if this has made it into a mainstrem JVM already. But if it does, it will be controlled by the runtime (thing -XX:something), not the developer.
The upside of this is that even old code can benefit from these future enhancements without itself being updated.
If you like to manually manage this (but still have the compiler check that it stays "safe"), take a look at Rust.