Author Archives: Stanislav_Panteleev

🔍 contains() in an ArrayList Just like in LinkedList, the contains() method in ArrayList: Iterates over the internal array from index 0 to size – 1. Uses .equals() to compare each element with the target.

🔍 contains() in a LinkedList What does it do? list.contains(element) checks whether the list contains a specific element. Internally, it: Starts from the head of the linked list. Iterates through each node. Uses .equals() to compare each node’s value with … Continue reading →

The answer is: it depends on what you’re doing. But generally: 🏎️ ArrayList is faster than LinkedList in most real-world use cases. Let’s break it down by operations:

✅ ArrayList Underlying Structure: Dynamic array. Access Time (get/set): O(1) – Direct access via index. Insert/Delete at End: O(1) amortized – Fast unless the array needs to resize. Insert/Delete in Middle/Beginning: O(n) – Requires shifting elements. Memory Usage: Less overhead, … Continue reading →

🕰️ Background: Why ArrayList was added if Vector already existed? ✅ Short Answer: ArrayList was introduced to fix the design limitations and performance issues of Vector.

Feature ArrayList Vector Introduced in JDK 1.2 (Collections Framework) JDK 1.0 (legacy class) Thread-safe? ❌ No (not synchronized) ✅ Yes (synchronized) Performance ✅ Faster (no locking overhead) ❌ Slower (due to synchronization) Growth mechanism Grows by 50% when full Grows … Continue reading →

🆚 Stack vs ArrayDeque — Why ArrayDeque wins 1. ✅ Performance Feature Stack ArrayDeque Underlying base Vector (synchronized) Resizable array (not synchronized) Thread-safe? Yes (but outdated style) No (but faster in single-threaded use) Performance Slower due to synchronization Faster — … Continue reading →

✅ The Stack is the classic Java collection that implements FILO behavior. Also called LIFO (Last-In-First-Out), meaning: The first element pushed is the last one popped.

✅ Queue — and its common implementations — are designed to follow the FIFO order. ✅ The Main FIFO Collection in Java: Queue Java’s Queue interface (from java.util) is specifically designed for FIFO behavior, where:

💥 Why does ConcurrentModificationException happen? It occurs when: You’re iterating over a collection (using an Iterator or for-each loop) And the collection is structurally modified outside the iterator during iteration