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 |
|
|
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· "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.