Where Do Classes, Objects, and Reference Variables Get Stored in Java: Stack vs Heap?

Where do classes, objects, and reference variables get stored in Java: stack or heap?

In Java, memory management is divided mainly into two areas: the stack and the heap. Understanding where classes, objects, and reference variables reside within these areas is crucial for effective programming and management of resources.

class Example {
    int variable;
    public void method() {
        Example obj = new Example(); // obj reference variable on stack, object in heap
    }
}

Causes

• Method-local variables and reference variables are stored on the stack.
• Objects created using 'new' are stored in the heap.
• The stack stores references to the objects in the heap.

Solutions

• Classes are stored in the method area of the heap during runtime.
• Objects are allocated memory in the heap when created with the 'new' keyword.
• Reference variables that point to these objects are stored on the stack.

Mistake: Confusing the stack and heap for variable storage.

Solution: Remember: stack is for reference and method-local variables; heap is for objects.

Mistake: Assuming all class-related structures are stored in the heap.

Solution: Classes themselves reside in the method area of the heap, while their instances are stored in the heap.