Java Collection (Hard)

Data Structures in Java

• A Queue data structure implements the First-In-First-Out principle.
• An ArrayDeque can be used both as a queue or a stack.
• A PriorityQueue is used to process objects based on priority.
• A Set data structure does not allow duplicate elements.
• A HashSet uses hashing to store elements in a hash table.
• An ArrayList allows iteration through elements in their order of insertion.
• A TreeSet maintains elements in ascending order.
• The Collection interface is the root interface for all collection classes.
• The Collection interface is implemented by all classes in the collection framework.
• The List interface extends the Collection interface and is used to store an ordered collection of objects.
• The ArrayList class implements the List interface and is a dynamic array that allows duplicate values.
• The Stack class is a subclass of Vector and implements the Last-In-First-Out principle.
• The LinkedList class implements List and Deque interfaces and is a linear data structure that consists of nodes instead of elements.
• The java.util package contains all the collections in Java.

Java Collections Framework

• The Java Collections Framework was introduced in JDK 1.2.
• The Java Collections Framework allows developers to create collections, manipulate them, and perform operations on them.
• The main purpose of the Java Collections Framework is to provide a set of classes and interfaces for working with collections.
• Before the Java Collections Framework was introduced, the standard collections used were not type-safe, which was a major problem.

ArrayList Methods

• The add method is used to add elements to the end of an ArrayList by default.
• The addAll method is used to add all the elements of a Collection to the end of an ArrayList in the order specified by the iterator.
• The get method is used to access the element at the specified index in an ArrayList.
• The contains method is used to check whether an ArrayList contains the specified element or not.
• The size method is used to return the size of an ArrayList.
• The ensureCapacity method is used to increase the capacity of an ArrayList, if necessary, to ensure that it can hold at least the number of elements specified in the argument.
• The remove method is used to remove an element from an ArrayList at the specified index.
• The set method is used to update an element in an ArrayList at the specified index.
• The sort method is used to sort the elements in an ArrayList in ascending order.