A stack and a heap are used for memory allocation in Java. However, the stack is used for primitive data types, temporary variables, object addresses etc. The heap is used for storing objects in memory.
Stacks and heaps in Java are explained in more detail as follows:
Stack in Java
Stacks are used to store temporary variables, primitive data types etc. A block in the stack exists for a variable only as long as the variable exists. After that, the block data is erased and it can be used for storing another variable.