In Java, the JVM memory is divided into two main regions: the stack and the heap. The stack is used for storing local variables and method calls, while the heap is used for storing objects.
The stack is a LIFO (Last-In-First-Out) data structure that stores method calls, local variables, and intermediate results of method calls. Every time a method is called, a new frame is created on the top of the stack, and when the method completes, the frame is removed from the stack. The stack is used for storing primitive data types such as int, boolean, char, etc. as well as references to objects that are stored in the heap.
The heap, on the other hand, is a region of memory that is used for dynamic memory allocation. It is a more flexible region of memory than the stack and is used for storing objects and their instance variables. When an object is created, it is allocated on the heap, and a reference to the object is stored on the stack. The heap is also used for storing arrays, which are objects in Java.
The main difference between the stack and the heap is that the stack is a fixed-size data structure, while the heap is a dynamically allocated region of memory. The stack has a limited amount of memory allocated to it, and this memory is freed when the method that created the stack frame completes. The heap, on the other hand, has a much larger amount of memory allocated to it and can grow as needed during the runtime of the program.
In summary, the stack is used for storing primitive data types, method calls, and references to objects, while the heap is used for storing objects and arrays. The stack has a fixed size and is freed automatically when the method call completes, while the heap is dynamically allocated and can grow as needed during the runtime of the program.