List Handling in Java vs C# vs C++ – A Deep Comparison
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In every software project, managing collections of data is a fundamental need. Lists (dynamic arrays) that grow and shrink at runtime are among the most common structures in any application, from simple TODO apps to complex trading systems.
Lists (or dynamic arrays) are fundamental to every language, but their implementation and behavior vary significantly across Java, C#, and C++. This comparison provides a full view of how these languages deal with list-like structures, from syntax to internals.
Basic Declaration
| Operation | Java | C# | C++ |
|---|---|---|---|
| Import | import java.util.*; | using System.Collections.Generic; | #include |
| Declare Empty List | List |
List |
std::vector |
| Add Element | list.add(10); | list.Add(10); | list.push_back(10); |
| Access Element | list.get(0); | list[0]; | list[0]; |
| Update Element | list.set(0, 100); | list[0] = 100; | list[0] = 100; |
Underlying Structure and Memory
| Feature / Operation | Java (ArrayList) | C# (List |
C++ (std::vector) |
|---|---|---|---|
| Type | ArrayList | List |
std::vector |
| Resizing Strategy | Doubles capacity | Doubles capacity | Implementation-defined (typically ×2) |
| Memory Storage | Heap | Heap | Stack + Heap (SSO for small types) |
| Thread-safe | ❌ (wrap with Collections.synchronizedList) | ❌ (use ConcurrentBag |
❌ (use std::mutex, tbb::concurrent_vector) |
| Initial Capacity | Default (10) | Default (0) | Default (0) |
| Pre-allocate | ensureCapacity(n) | new List |
reserve(n) |
| Shrink memory | trimToSize() | TrimExcess() | shrink_to_fit() |
| Out of Bounds Access | Throws IndexOutOfBoundsException | Throws ArgumentOutOfRangeException | Undefined behavior (no bound check by default) |
Common Operations
| Operation | Java | C# | C++ |
|---|---|---|---|
| Add Element | add(x) | Add(x) | push_back(x) |
| Insert at Index | add(i, x) | Insert(i, x) | insert(list.begin() + i, x) |
| Remove by Index | remove(i) | RemoveAt(i) | erase(list.begin() + i) |
| Remove by Value | remove(Integer.valueOf(x)) | Remove(x) | remove(list.begin(), list.end(), x) |
| Check Existence | contains(x) | Contains(x) | std::find(...) != end() |
| Sort List | Collections.sort(list) | list.Sort() | std::sort(list.begin(), list.end()) |
| Clear List | clear() | Clear() | clear() |
| Size / Length | size() | Count | size() |
| Convert to Array | list.toArray() | list.ToArray() | std::vector |
| Clone / Copy | new ArrayList<>(original) | new List |
std::vector |
| Equality Comparison | list.equals(otherList) | list.SequenceEqual(otherList) | vec1 == vec2 (C++20), or std::equal(...) |
| Check Empty | list.isEmpty() | list.Count == 0 | vec.empty() |
Performance Characteristics
| Feature | Java (ArrayList) | C# (List |
C++ (std::vector) |
|---|---|---|---|
| Index Access | O(1) | O(1) | O(1) |
| Insertion at End | Amortized O(1) | Amortized O(1) | Amortized O(1) |
| Insertion at Start | O(n) | O(n) | O(n) |
| Memory Reallocation | Triggered on resize | Triggered on resize | May use reserve() to avoid |
- Java: Use ensureCapacity() to avoid resizing.
- C#: Use .Capacity = n or list = new List<int>(capacity);
- C++: Use reserve(n) and avoid invalidating iterators.
Advanced Features
| Feature | Java | C# | C++ |
|---|---|---|---|
| Custom Sort Comparator | Collections.sort(list, cmp) | list.Sort(comparer) | std::sort(..., comparator) |
| Functional-style Ops | Java Streams (from Java 8) | LINQ | Ranges (from C++20) |
| Parallel Processing | parallelStream() | AsParallel() | std::execution::par (C++17) |
| Thread-safe Version | Collections.synchronizedList() | ConcurrentBag |
std::mutex or concurrent_vector (TBB) |