Скачать или смотреть Selenium automation testing course with Java- Collections -LinkedList- class 22

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class 22:-

LinkedList in java:-
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A LinkedList in Java is a part of the Java Collections Framework, present in the java.util package. It is a linear data structure where elements (called nodes) are stored in non-contiguous memory locations. Each node points to the next (and optionally the previous) node in the sequence.
Java provides a doubly linked list implementation through the LinkedList class, meaning:
Each node contains:
Data + Pointer to Previous Node + Pointer to Next Node

Key Characteristics of LinkedList
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Implements: List, Deque, Queue interfaces
Allows: Duplicate elements
Maintains: Insertion order
Not synchronized (i.e., not thread-safe)
Efficient for: Insertion and deletion in the middle of the list

Common Methods in LinkedList
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Method Description
add(E e) Adds element to the end
addFirst(E e) Adds to the beginning
addLast(E e) Adds to the end
remove() Removes and returns first element
remove(int index) Removes at index
get(int index) Returns element at index
getFirst() Returns first element
getLast() Returns last element
size() Returns the number of elements

ArrayList vs LinkedList
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Feature ArrayList LinkedList
Memory Uses a dynamic array Uses doubly linked list
Access Time Fast (O(1) for index-based access) Slow (O(n) traversal)
Insertion/Deletion Slow in middle (O(n)) Fast in middle (O(1)) if node reference known
Search O(n) O(n)
Memory Usage Less (just data) More (data + 2 pointers)
Resizing May need array resizing No resizing needed
Best For Read-heavy operations Insert/delete-heavy operations
When to Use LinkedList?
Use LinkedList when:
You need constant-time insertions/removals from the beginning or middle
You don’t need fast random access

Avoid if:
You often access elements by index (use ArrayList instead)