Stack frames
Description
Each method call has local working space.
Explanation
When the method returns, its local frame is removed.
Example
int score = 90;← Chapter 5 — Arrays, Memory & Methods
20. Stack & Heap Memory
mixed
Description
Java manages memory automatically, but a simple mental model helps you understand variables. Local variables and method calls are associated with the stack, while objects and arrays live on the heap.
A reference variable holds a way to reach an object, not a full copy of that object. Multiple references can point to the same object.
Subtopics
Heap objects
Description
Objects are created with new.
Explanation
Garbage collection may reclaim unreachable objects.
Example
int[] scores = new int[3];Explanation
Do not try to manually free Java objects. Instead, avoid retaining references you no longer need and use try-with-resources for files, sockets, and similar resources.
Example
public class MemoryDemo {
public static void main(String[] args) {
int[] scores = {70, 80, 90};
int[] sameScores = scores;
sameScores[0] = 75;
System.out.println(scores[0]);
}
}Key points
- Local method work uses stack frames.
- Objects and arrays are heap allocated.
- References can share one object.