Explain the main differences between the Stack and Heap memory areas in the Java virtual machine.

The Java Virtual Machine divides memory into two main areas: Stack and Heap.

• Stack — this is the memory area where local variables of methods and information about function calls (stack frames) are stored. Each thread has its own stack. Access to data in the stack is very fast, and memory is allocated and freed automatically when entering and exiting methods. Primitive types and references to objects are stored in the stack.

• Heap — this is the memory area where objects and arrays created dynamically using the new operator are stored. The heap is shared among all threads, and memory management here is handled by the garbage collector. Objects in the heap live as long as there are references to them.

In brief:

• Stack: fast access, stores local variables and method calls, size is limited.
• Heap: stores objects, managed by the garbage collector, usually larger and dynamic.

Example:

public void example() {
    int a = 10; // variable a is stored in the stack
    MyObject obj = new MyObject(); // reference obj in the stack, object in the heap
}