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Array List
In Java, `ArrayList` is a dynamic array-like data structure provided by the Java Collections Framework. It extends the capabilities of arrays by allowing them to grow dynamically and handle variable-sized collections of elements. `ArrayList` is part of the "Collections" topic in Java, which focuses on data structures designed to store and manipulate groups of objects. It provides methods to add, remove, access, and manipulate elements efficiently. `ArrayList` maintains elements in insertion order and allows elements to be accessed using an index. It is widely used in Java programming for its flexibility, efficiency, and ease of use compared to traditional arrays. Understanding `ArrayList` and the broader Java Collections Framework is essential for developing efficient and scalable Java applications that require handling and managing collections of data effectively.
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02:35min
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Linked List
In Java, `LinkedList` is a class that implements the `List` interface and represents a linear data structure where elements are stored in a sequence of nodes. Each node contains a reference to the next node in the sequence, making it an ideal choice for scenarios where frequent insertions and deletions are required. `LinkedList` provides methods to add, remove, and manipulate elements at both ends (head and tail) of the list, as well as at specified positions. It supports both sequential and indexed access to its elements. `LinkedList` falls under the "Collections" topic in Java, which encompasses various data structures designed to store and manage collections of objects efficiently. Understanding `LinkedList` and its operations is essential for developers needing to work with dynamic lists and perform operations that involve frequent modifications to the list structure.
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06:17min
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Deque
In Java, `Deque` (pronounced as "deck") stands for double-ended queue, and it is an interface in the Java Collections Framework that extends the `Queue` interface. A `Deque` allows elements to be added or removed from both ends, either as a first-in-first-out (FIFO) queue or as a last-in-first-out (LIFO) stack. It supports operations such as adding elements (`addFirst`, `addLast`), removing elements (`removeFirst`, `removeLast`), and accessing elements (`getFirst`, `getLast`) from both ends of the deque. Implementations of the `Deque` interface include classes like `ArrayDeque` and `LinkedList`. `Deque` falls under the "Collections" topic in Java, which focuses on data structures designed to store and manipulate groups of objects efficiently. Understanding `Deque` and its implementations is important for scenarios where flexible manipulation of elements from both ends of the collection is required, such as in algorithms involving dequeues, double-ended queues, or stacks.
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05:59min
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Hashset
In Java, `HashSet` is a class that implements the `Set` interface and represents a collection of unique elements where duplicates are not allowed. It uses a hash table for storing elements, which provides constant-time performance for basic operations like add, remove, contains, and size, assuming a good hash function. `HashSet` does not guarantee the order of elements and allows `null` elements (only one null element is allowed). It falls under the "Collections" topic in Java, which encompasses data structures designed to store and manage groups of objects efficiently. `HashSet` is widely used for scenarios where uniqueness of elements and efficient membership testing are required, such as in removing duplicates from collections or implementing data structures that require fast lookup operations. Understanding `HashSet` and its characteristics is crucial for leveraging its performance benefits in Java applications.
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05:18min
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Linked Hashset
In Java, `LinkedHashSet` is a class that extends `HashSet` and maintains a doubly linked list running through all of its entries. This linked list defines the iteration order, which is the order in which elements were inserted into the set (insertion-order). Like `HashSet`, `LinkedHashSet` also does not allow duplicate elements and permits `null` elements (only one null element). It provides O(1) time complexity for basic operations such as add, remove, contains, and size, assuming a good hash function. `LinkedHashSet` preserves the order of insertion, making it suitable for applications that require predictable iteration order along with the benefits of hash table-based access. `LinkedHashSet` falls under the "Collections" topic in Java, specifically within the subset of data structures designed for maintaining unique elements with predictable iteration order. Understanding `LinkedHashSet` is important for scenarios where maintaining the order of elements as they are added to the set is necessary.
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06:00min
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Stack
In Java, `Stack` is a class that represents a Last-In-First-Out (LIFO) stack of objects. It extends the `Vector` class with five operations that allow a vector to be treated as a stack. The usual push and pop operations are provided, as well as methods to peek at the top item, test for an empty stack, and search for an item and find its position. `Stack` falls under the broader topic of "Collections" in Java, specifically within the subset of data structures designed for managing elements based on the Last-In-First-Out (LIFO) principle. Understanding `Stack` is essential for applications where elements need to be added and removed in a last-in-first-out manner, such as in parsing, recursive algorithms, undo mechanisms, and other scenarios where order of operations is critical.
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07:32min
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HashMap
In Java, `HashMap` is a class that implements the `Map` interface and represents a collection of key-value pairs. It uses a hash table for storing the elements, where each key-value pair is stored in a bucket based on the hash code of the key. `HashMap` provides constant-time performance for basic operations such as `put` (adding an element), `get` (retrieving an element), `containsKey` (checking if a key exists), and `remove` (deleting an element), assuming a good hash function. It does not maintain any order of the keys or values. `HashMap` allows null values and at most one null key. `HashMap` falls under the "Collections" topic in Java, which focuses on data structures designed to store and manage associations between keys and values efficiently. Understanding `HashMap` is crucial for applications that require fast lookup, insertion, and deletion operations based on keys, such as caching, indexing, and storing configuration settings.
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09:05min
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Linked HashMap
In Java, `LinkedHashMap` is a class that extends `HashMap` and maintains a doubly linked list running through all of its entries. This linked list defines the iteration order, which is the order in which entries were inserted into the map (insertion-order). `LinkedHashMap` provides predictable iteration order, unlike `HashMap`, which does not guarantee any specific order of iteration. Like `HashMap`, `LinkedHashMap` also allows null keys and values (only one null key), and it provides constant-time performance for basic operations such as `put`, `get`, `containsKey`, and `remove`, assuming a good hash function. `LinkedHashMap` is part of the "Collections" topic in Java, specifically within the subset of data structures designed for maintaining key-value associations with predictable iteration order based on insertion sequence. Understanding `LinkedHashMap` is important for applications where maintaining the order of entries as they were added to the map is required, such as in caching, logging, and maintaining configuration settings.
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08:43min
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Tree Map
In Java, `TreeMap` is a class that implements the `NavigableMap` interface and extends `AbstractMap`. It stores key-value pairs in a sorted order based on the natural ordering of its keys or a custom `Comparator` provided at the time of creation. `TreeMap` uses a Red-Black tree for storage, which guarantees log(n) time complexity for key-based operations like `put`, `get`, `remove`, and `containsKey`. This data structure allows efficient retrieval of keys in sorted order and supports operations like finding the first or last key, key range queries, and navigating through the map using its sorted keys. `TreeMap` falls under the "Collections" topic in Java, specifically within the subset of data structures designed for maintaining key-value associations in sorted order. Understanding `TreeMap` is crucial for applications that require sorted mappings and operations based on keys, such as dictionaries, sorted mappings, and range queries.
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07:40min
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Tree Set
In Java, `TreeSet` is a class that implements the `NavigableSet` interface and extends `AbstractSet`. It stores elements in sorted order using a Red-Black tree, which ensures that elements are maintained in ascending order based on their natural ordering or a custom `Comparator` provided during creation. `TreeSet` does not allow duplicate elements and provides efficient operations such as `add`, `remove`, `contains`, and retrieval of elements in sorted order. It supports operations like finding the first or last element, range queries, and navigating through the set using its sorted elements. `TreeSet` falls under the "Collections" topic in Java, specifically within the subset of data structures designed for maintaining sorted collections of unique elements. Understanding `TreeSet` is important for applications that require elements to be stored and accessed in a sorted manner, such as maintaining ordered collections and performing range-based operations efficiently.
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04:45min
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Type Casting
In Java, type casting refers to the process of converting a variable of one data type into another. It allows a variable to be treated as a different type temporarily, either widening or narrowing its original type. Type casting is necessary when assigning a value of one primitive data type to another or when converting between object types, especially in inheritance hierarchies where polymorphism is involved. Type casting can be explicit, where the programmer explicitly specifies the conversion using syntax like `(type) expression`, or implicit, where Java automatically performs the conversion when compatible data types are involved, such as widening conversions from smaller to larger data types. Type casting falls under the topic of "Type Conversion" or "Type Casting" in Java programming, which is fundamental for managing data types and ensuring compatibility in various programming scenarios. Understanding type casting is crucial for handling data transformations effectively and avoiding type-related errors in Java applications.
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03:19min
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PriorityQueue
In Java, `PriorityQueue` is a class that implements the `Queue` interface and represents a priority queue based on the priority specified by a comparator or the natural ordering of elements. Elements in a `PriorityQueue` are ordered either according to their natural ordering or by a specified comparator. The queue retrieves elements based on their priority; elements with higher priority are dequeued before elements with lower priority. `PriorityQueue` is implemented as a binary heap, which provides logarithmic time complexity for most operations like insertion (`offer`), removal (`poll`), and retrieval of the highest-priority element (`peek`). `PriorityQueue` falls under the "Collections" topic in Java, specifically within the subset of data structures designed for managing elements based on priority. Understanding `PriorityQueue` is important for applications where tasks, events, or objects need to be processed in order of priority, such as job scheduling, event processing, and graph algorithms like Dijkstra's shortest path algorithm.
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06:51min
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