Feature

ArrayList

LinkedList

Underlying Data Structure

Dynamic array

Doubly-linked list

Access Time

O(1) (constant time) for accessing elements by index

O(n) (linear time) for accessing elements by index

Insertion Time

O(1) (amortized) when adding at the end, O(n) when adding at specific positions

O(1) when adding at the beginning or end, O(n) when adding at specific positions

Deletion Time

O(n) (due to shifting elements)

O(1) when removing the first or last element, O(n) for other positions

Memory Usage

Less memory overhead (only data stored)

More memory overhead (due to storage of next and previous pointers)

Iteration Performance

Fast iteration (O(n))

Fast iteration (O(n)), but slower compared to ArrayList due to node traversal

Use Case

Best for read-heavy applications where frequent access by index is needed

Best for write-heavy applications where frequent insertions and deletions are needed

Growth

Needs to resize and copy elements when capacity is exceeded

Does not require resizing; grows dynamically

Resizing Cost

High (due to copying elements to a new array)

None (nodes are linked dynamically)

Random Access

Supported and efficient

Not supported efficiently

Insert/Delete in Middle

Inefficient due to shifting elements

Efficient as it only involves updating pointers

Iteration Order

Maintains order of insertion

Maintains order of insertion

Implementation

List<String> list = new ArrayList<>();

List<String> list = new LinkedList<>();

Ideal For

Scenarios with frequent element access and rare insertions/deletions

Scenarios with frequent insertions/deletions and rare element access

 

ArrayList

LinkedList

Uses an array to store elements.

 

Uses a doubly linked list to store elements.

 

Provides fast random access using index-based operations.

 

Provides slower random access since it requires traversing the list from the beginning.

 

Insertion and deletion in the middle of the list can be slower due to shifting elements.

Insertion and deletion at any position in the list is faster.

 

Requires less memory compared to LinkedList.

 

Requires more memory due to the additional overhead of storing references to previous and next nodes.

 

Does not implement the Deque interface.

 

Implements the Deque interface, providing first-in-first-out operations.

 

Suitable for scenarios where random access is important and the number of insertions and deletions is relatively low.

Suitable for scenarios where frequent insertions and deletions at any position are required, but random access is not a primary concern.

 

 

Aspect

ArrayList

LinkedList

Internal Implementation

Uses a dynamic array to store elements

Uses a doubly linked list to store elements 

Memory Usage

Elements stored in contiguous memory locations

Elements stored in non-contiguous memory locations using nodes with pointers 

Accessing Elements

Faster for accessing elements by index 

Slower for accessing elements by index, requires traversal 

Inserting/Removing Elements

Slower due to shifting of elements 

Faster, only requires updating node pointers 

Memory Overhead

Some overhead for array data and resizing 

Additional overhead for storing node pointers 

Functionality

Implements only the List interface 

Implements List and Deque interfaces, can function as a queue 

Preferred Usage

Storing and accessing data 

Manipulating data with frequent insertions/deletions 

 

Category

ArrayList

LinkedList

Implementation

Dynamic array

Doubly-linked list

Element Access

Constant time (O(1))

Linear time (O(n))

Insertion/Deletion

Slow in the middle (O(n))

Constant time at the start/end (O(1))

Linear time in the middle (O(n))

Memory Overhead

Lower memory usage

Higher memory usage

Use Cases

Frequent data retrieval

Frequent insertions/deletions

Random access

Sequential access

Cache-Friendly

Yes

No

 

 

 

·        "Element Access" refers to the time complexity of accessing a specific element in the list.

·        "Insertion/Deletion" refers to the time complexity of adding or removing elements from the list.

·        "Memory Overhead" indicates the relative memory usage of each data structure.

·        "Use Cases" highlights the scenarios where each data structure is typically preferred.

·        "Cache-Friendly" indicates whether the data structure is designed to optimize cache performance.