Is a primitive object field stored in the heap or in the stack?

In Java, primitive fields of an object are always stored inside the object, which resides in the heap.

Explanation:

• Objects in Java are created in the heap.
• All fields of an object (primitive and reference) are part of the object and are stored together with it in the heap.
• Primitive fields occupy a fixed space within the object.

The stack is used to store local variables of methods, including references to objects, but not for storing the objects themselves or their fields.

Example:

class MyClass {
    int number; // primitive field
}

MyClass obj = new MyClass();

Here, obj is a reference stored in the stack (if it's a local variable), and the MyClass object with the number field is in the heap.

In summary: a primitive field of an object resides in the heap, inside the object.