ArrayList class in java
ArrayList is a class in Java that provides a dynamic array implementation. It allows for the dynamic resizing of the underlying array, insertion and removal of elements at any position, and provides various methods for accessing and manipulating the elements in the list. ArrayList is part of the Java Collections Framework and is commonly used for storing and manipulating collections of objects in Java programs.
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LinkedList Class in java
LinkedList is a class in Java that provides a doubly-linked list implementation. It allows for efficient insertion and removal of elements at any position in the list, but provides slower access times than ArrayList because elements must be traversed sequentially to access a specific element. LinkedList is also part of the Java Collections Framework and can be used for storing and manipulating collections of objects in Java programs.
Iterator and ListIterator interface in java
Iterator and ListIterator are interfaces in Java that provide a way to traverse and manipulate collections of objects.
The Iterator interface provides a way to traverse a collection in a forward-only manner and perform operations like removing elements while iterating over the collection. It provides three methods:
hasNext() to check if there are more elements in the collection,
next() to retrieve the next element, and
remove() to remove the current element from the collection.
The ListIterator interface extends Iterator and provides additional methods to traverse a list in both forward and backward directions, and perform operations like adding and setting elements. It provides methods like
next() similar to Iterator, as well as
previous() to traverse the list in a backward direction. Additionally, ListIterator provides
remove() methods to insert, replace, and remove elements while iterating over the list.
HashSet Class in java
HashSet is a class in Java that implements the Set interface, which is used to store a collection of unique elements. HashSet is implemented using a hash table, which provides fast insertion, deletion, and lookup operations. HashSet does not guarantee the order of its elements, and allows for null values.
HashSet provides various methods for adding, removing, and checking the presence of elements in the set, such as
contains(). It also provides methods to obtain the size of the set and to convert the set to an array. HashSet is part of the Java Collections Framework and is commonly used for storing and manipulating collections of objects in Java programs.
LinkedHashSet Class in java
LinkedHashSet is a class in Java that extends HashSet and provides a set implementation with predictable iteration order. It maintains the insertion order of its elements, which is the order in which elements were inserted into the set. LinkedHashSet is implemented using a combination of a hash table and a doubly-linked list, which provides fast insertion, deletion, and lookup operations while also preserving the order of elements.
LinkedHashSet provides the same methods as HashSet for adding, removing, and checking the presence of elements in the set. It also provides methods for obtaining the size of the set, converting the set to an array, and iterating over the set in the order of insertion. LinkedHashSet is part of the Java Collections Framework and is commonly used for maintaining a collection of unique elements in Java programs while preserving the insertion order.