Author Archives: Stanislav_Panteleev

✅ Difference Between WeakReference and SoftReference Feature WeakReference SoftReference GC behavior Collected as soon as no strong refs Collected only when memory is low Lifespan Short Longer (survives longer in memory) Use case Automatic cleanup Memory-sensitive cache So in theory: … Continue reading →

This is one of the most fundamental and fascinating topics in Java memory management. Let’s go through all 4 types of references in Java, how the Garbage Collector (GC) treats them, and when you’d use each one.

In Java, a weak reference is a type of reference that does not prevent an object from being garbage collected. ✅ In plain terms: If an object is only weakly referenced (i.e., no strong references point to it), then the … Continue reading →

Let’s talk about HashMap vs WeakHashMap, and why the second one is super useful in certain cases. 🔍 Main Difference Feature HashMap WeakHashMap Key reference type Strong references Weak references Garbage collection Keys are never GC’d if referenced Keys can … Continue reading →

Let’s get into the difference between HashMap and IdentityHashMap, and when to use this strange beast of a map. 🎯 TL;DR: ✅ HashMap compares keys using .equals()✅ IdentityHashMap compares keys using == (object reference equality) That’s the core difference — … Continue reading →

🧓 First, a bit of history Hashtable is part of the original Java 1.0. HashMap was introduced in Java 1.2 as part of the new Collections Framework.

in modern Java, the Stack class is generally considered obsolete or legacy. Let’s break it down 👇 🛑 Why Stack is considered obsolete 😬 Problems: It extends Vector, which is: A synchronized, thread-safe collection — unnecessary overhead for most use … Continue reading →

The PriorityQueue in Java is a powerful tool for managing elements based on priority rather than insertion order — super useful in many real-world scenarios like scheduling, simulations, and pathfinding algorithms (like Dijkstra!).

🔄 Reversely iterating over a LinkedList without using get(index) is a smart move — because get(i) on a LinkedList is O(n), and doing it in a loop would give you O(n²) total time 😱. ✅ Best way: Use DescendingIterator LinkedList … Continue reading →

✅ Java’s LinkedList is Doubly Linked Each node in Java’s LinkedList contains: A reference to the next node A reference to the previous node A value So it’s a classic doubly linked list.