You can do that, and people do. However a GC language doesn't normally give you the flexibility of getting a block of memory and doing whatever you want inside it, instead you use things like object pools.
You can allocate a block of memory with `ByteBuffer.allocate()` or, if you want it outside the JVM heap, `ByteBuffer.allocateDirect()`.
You lose all the object/memory management features, though there are some projects around to provide struct-like APIs: https://github.com/alaisi/nalloc
