Resource Management in C#, Java, and Kotlin

IDisposable vs Using vs Try-With-Resources vs Kotlin use

Modern applications interact constantly with files, databases, sockets, streams, and network connections. Managing these resources incorrectly leads to memory leaks, locked files, exhausted connections, and production outages.

C#, Java, and Kotlin all solve this problem—but in different, language-specific ways.

This article provides a clear, practical comparison of how deterministic resource cleanup works across these three ecosystems, with real-world examples and best practices.

Why Resource Management Matters

Garbage collection does not manage external resources such as:

• File handles
• Database connections
• Network sockets
• OS-level memory

If these are not released explicitly and deterministically, your application will fail under load.

This is where language-level resource management patterns come in.

C#: IDisposable and using

The C# Approach

C# uses the IDisposable interface and the using statement to guarantee cleanup.

Example

using (var reader = new StreamReader("data.txt"))
{
    var content = reader.ReadToEnd();
}
// Dispose() is called automatically

Key Characteristics

• IDisposable exposes Dispose()
• using guarantees Dispose() execution
• Cleanup is deterministic
• Works even during exceptions
• Supports async via IAsyncDisposable and await using

Best Use Cases

• File and stream handling
• Database connections
• Short-lived system resources

Java: AutoCloseable and Try-With-Resources

The Java Approach

Java uses the AutoCloseable interface with try-with-resources.

Example

try (BufferedReader reader =
         new BufferedReader(new FileReader("data.txt"))) {
    String line = reader.readLine();
}
// close() is called automatically

Key Characteristics

• AutoCloseable.close() handles cleanup
• Resources close in reverse order
• Exceptions in close() are suppressed
• finalize() is deprecated and should not be used

Best Use Cases

• JDBC connections
• Streams and file I/O
• Network resources

Kotlin: use {} – The Idiomatic JVM Approach

The Kotlin Advantage

Kotlin builds on Java but improves readability and safety using the use {} extension.

Example

FileReader("data.txt").use { reader ->
    val content = reader.readText()
}

Why Developers Prefer It

• Less boilerplate than Java
• Fully exception-safe
• Works with any AutoCloseable
• Idiomatic and concise

Important Note

use {} closes the resource at the end of the lambda, not the function.

Side-by-Side Comparison

Practical Ownership Rule (All Languages)

The code that creates a resource is responsible for closing it.

Violating this rule leads to:

• Connection leaks
• File locks
• Thread starvation
• Production instability

Common Mistakes to Avoid

❌ Forgetting to close resources

BufferedReader reader = new BufferedReader(...);
// never closed

❌ Overusing short-lived Http clients

// Bad practice
using var client = new HttpClient();

❌ Letting resources escape coroutine scopes (Kotlin)

FileReader("file.txt").use {
    launch { /* unsafe */ }
}

Final Thoughts

Although the syntax differs, C#, Java, and Kotlin share the same philosophy:

Garbage collection manages memory — you manage resources.

• C# offers the most advanced disposal model
• Java provides strong guarantees with verbosity
• Kotlin delivers elegance without sacrificing safety

Mastering these patterns is essential for high-performance, production-grade software.