Difference Between ArrayList and LinkedList in Java

In Java, ArrayList and LinkedList are two popular classes that implement the List interface in the Java Collections Framework. Both are used to store ordered collections of elements, but they differ significantly in performance and internal working.

Understanding their differences is very important for students and freshers because this is a very common Java interview question.

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✅ What is ArrayList?

An ArrayList uses a dynamic array internally to store elements.

Example:

import java.util.ArrayList;

ArrayList<String> list = new ArrayList<>();
list.add("Java");
list.add("Spring");
list.add("Hibernate");

System.out.println(list);

Key Features:

• Maintains insertion order
• Fast data retrieval using index
• Dynamic resizing
• Better for read operations

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✅ What is LinkedList?

A LinkedList uses a doubly linked list structure where each element stores references to previous and next elements.

Example:

import java.util.LinkedList;

LinkedList<String> list = new LinkedList<>();
list.add("Java");
list.add("Spring");
list.add("Hibernate");

System.out.println(list);

Key Features:

• Efficient insertion and deletion
• No shifting of elements
• Suitable for frequent modifications

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📊 Difference Between ArrayList and LinkedList

Feature	ArrayList	LinkedList
Internal Structure	Dynamic Array	Doubly Linked List
Access Time	Faster (O(1))	Slower (O(n))
Insertion/Deletion	Slower	Faster
Memory Usage	Less	More (extra pointers)
Best Use Case	Read-heavy operations	Insert/Delete-heavy operations

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✅ Performance Comparison

• ArrayList → Best when data is accessed frequently.
• LinkedList → Best when elements are frequently added or removed.

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🎯 Interview Tip

A common interview question:

👉 Why is ArrayList faster than LinkedList for searching?

Because ArrayList supports direct index-based access, while LinkedList must traverse nodes one by one.

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