Why do people still use primitive types in Java?

Question

Since Java 5, we\'ve had boxing/unboxing of primitive types so that int is wrapped to be java.lang.Integer, and so and and so forth.

I see

Answer 1

By the way, Smalltalk has only objects (no primitives), and yet they had optimized their small integers (using not all 32 bits, only 27 or such) to not allocate any heap space, but simply use a special bit pattern. Also other common objects (true, false, null) had special bit patterns here.

So, at least on 64-bit JVMs (with a 64 bit pointer namespace) it should be possible to not have any objects of Integer, Character, Byte, Short, Boolean, Float (and small Long) at all (apart from these created by explicit new ...()), only special bit patterns, which could be manipulated by the normal operators quite efficiently.