Summary - Java Collections Framework - Part 1

Collection Hierarchy

The Java Collection Framework provides a well-designed set of interfaces and classes to handle groups of objects. Here is a detailed look at the hierarchy:

Collection Interface: Root interface with methods like add(E e), remove(Object o), size(), etc.

List Interface: Extends Collection, ordered and allows duplicates.

ArrayList: Dynamic array, fast random access, slower middle operations.

LinkedList: Doubly-linked list, efficient insertions/deletions, acts as list and queue.

Vector: Synchronized array, thread-safe but slower, legacy class.

Stack: Extends Vector, LIFO stack operations.

Set Interface: Extends Collection, no duplicates.

HashSet: Backed by hash table, unordered.

LinkedHashSet: HashSet with iteration order.

TreeSet: NavigableSet, sorted.

Queue Interface: Extends Collection, holds multiple elements prior to processing.

PriorityQueue: Priority heap, ordered.

LinkedList: Also used as a queue.

Map Interface: Maps keys to values, not a true collection.

HashMap: Backed by hash table, allows null values.

LinkedHashMap: HashMap with iteration order.

TreeMap: Sorted map.

Hashtable: Synchronized map, legacy class.

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List Interface and Its Implementations

ArrayList: Dynamic array, fast random access, slower middle operations.

LinkedList: Doubly-linked list, efficient insertions/deletions, acts as list and queue.

Vector: Synchronized array, thread-safe but slower, legacy class.

Stack: Extends Vector, LIFO stack operations.

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Iterator and Iterable Interfaces

Iterable Interface: Implemented by classes whose objects can be iterated, method iterator().

Iterator Interface: Traverses elements, methods hasNext(), next(), remove().

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Collection Framework Utilities

Collections Class: Utility class for collections.

Methods: sort(), reverse(), shuffle(), binarySearch(), copy(), fill(), min(), max(), synchronizedList().

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Comparator and Comparable

Comparable Interface: Defines natural ordering, method compareTo().

Comparator Interface: Defines custom ordering, method compare().

Differences: Comparable is part of the class, Comparator is separate.

Understanding Java Collections provides developers with more flexibility over data structures. For more detailed information, refer to the Notion link:

Java Collections - Part 1⁠

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