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Introduction An ArrayDeque in Java is a part of the java.util package and is used as a resizable, double-ended queue (deque). It allows adding and removing elements from both ends efficiently and is faster than LinkedList for stack and queue operations. 1. Data Structure Used ArrayDeque is implemented using a circular array, which allows efficient insertions and deletions from both ends. Implementation in Java: 2. How Elements are Stored and…
Introduction A PriorityQueue in Java is a part of the java.util package and is used to store elements in a priority-based order. Unlike a normal queue (FIFO), PriorityQueue orders its elements based on natural ordering (for Comparable objects) or custom order defined by a Comparator. 1. Data Structure Used PriorityQueue is implemented using a binary heap, which ensures efficient retrieval of the highest or lowest priority element. Implementation in Java:…
Introduction A TreeSet in Java is a part of the java.util package and is used to store unique elements in sorted order. Unlike HashSet, which does not maintain order, TreeSet is implemented using a self-balancing Red-Black Tree, ensuring that elements are always stored in ascending order or a custom order defined by a comparator. 1. Data Structure Used TreeSet is implemented using a TreeMap, which internally uses a Red-Black Tree…
Introduction A LinkedHashSet in Java is a part of the java.util package and is used to store unique elements while maintaining insertion order. It extends HashSet and uses a linked list to maintain order. Unlike HashSet, which does not guarantee the order of elements, LinkedHashSet ensures elements are returned in the same order they were inserted. 1. Data Structure Used LinkedHashSet is implemented using a combination of HashMap and a…
Introduction A Vector in Java is a part of the java.util package and is used to store a dynamic array similar to ArrayList. However, Vector is synchronized, making it thread-safe but slower in comparison to ArrayList. 1. Data Structure Used Vector is implemented using a dynamic array, meaning it grows automatically when more elements are added. Implementation in Java: 2. How Elements are Stored and Accessed Adding an Element When…
Introduction A LinkedList in Java is a part of the java.util package and is used to store elements in a doubly linked list structure. Unlike ArrayList, which uses a dynamic array, LinkedList consists of nodes that store data and references to the next and previous nodes. 1. Data Structure Used LinkedList is implemented using a doubly linked list where each node contains: Implementation in Java: When a LinkedList is created,…
Introduction An ArrayList in Java is a part of the java.util package and is used to store dynamic arrays. Unlike arrays, ArrayList can grow dynamically when elements are added, making it more flexible. 1. Data Structure Used ArrayList is implemented using an array internally. The key feature of ArrayList is its ability to resize dynamically when elements are added or removed. Implementation in Java: 2. How Elements are Stored and…
Introduction A TreeMap in Java is a part of the java.util package and is used to store key-value pairs in sorted order based on the natural ordering of keys or a custom comparator. Unlike HashMap, which provides constant-time performance (O(1)) for basic operations, TreeMap provides logarithmic time complexity (O(log n)) as it is implemented using a Red-Black Tree. 1. Data Structure Used A TreeMap is implemented as a Red-Black Tree,…
Introduction A HashMap in Java is a part of the java.util package and is used to store key-value pairs. It provides fast lookups, insertions, and deletions with an average time complexity of O(1). It internally uses a hashing mechanism to map keys to values efficiently. 1. Data Structure Used HashMap is implemented using an array of linked lists (or Red-Black Trees for optimization in Java 8+). Each bucket in the…
Introduction A HashSet in Java is a part of the java.util package and is used to store unique elements. It is backed by a HashMap, which helps in achieving constant-time complexity (O(1)) for add, remove, and contains operations. Internal Working of HashSet 1. Data Structure Used HashSet internally uses a HashMap<K, V> with a dummy value. Each element in the HashSet acts as a key in the HashMap, and the…