I've been working very hard to make Java use less memory using techniques like these and others more. The problem is, if you really want to specify exactly how non-trivial structured objects are packed into memory, you end up writing your own garbage collector and memory allocator, which is a rather large project all by itself. Also, I have found that cutting down on memory usage like that hurts performance a lot.

At the end of the day, going down that road makes you less productive than working in C++ and the result will still be subpar compared to a C or C++ solution. So I'm back with C++ right now even though I'm painfully aware of its weaknesses.