Memory Management & Garbage Collection

Java manages memory automatically — objects live on the heap, and the garbage collector (GC) periodically reclaims any object no longer reachable from a running thread, so there's no manual free() or delete as in C or C++.

void createObjects() {
    for (int i = 0; i < 1000; i++) {
        String temp = "item " + i; // eligible for GC once the loop moves on
    }
}

A StackOverflowError happens when the call stack (holding local variables and return addresses for each active method call) grows too deep, usually from unbounded recursion; an OutOfMemoryError happens when the heap genuinely runs out of room even after garbage collection.

Common mistakes

• Holding a reference to an object longer than needed (e.g. in a static collection that keeps growing) — this prevents the GC from ever reclaiming it, a pattern known as a memory leak even in a garbage-collected language.