Resource Leak: Stream Not Closed

Why This Happens

Streams, connections, and other resources that implement AutoCloseable must be closed after use to release system resources. Not closing them causes resource leaks that can lead to file descriptor exhaustion, connection pool depletion, and memory leaks.

The Problem

InputStream in = new FileInputStream("data.txt");
byte[] data = in.readAllBytes();
// Stream never closed - resource leak!

The Fix

try (InputStream in = new FileInputStream("data.txt")) {
    byte[] data = in.readAllBytes();
} // Automatically closed here, even if an exception occurs

Step-by-Step Fix

1. 1

   Identify the leaked resource

   Find the resource (stream, connection, reader) that is opened but not closed in all code paths.

2. 2

   Check for try-with-resources

   Verify that the resource is declared in a try-with-resources statement.

3. 3

   Add try-with-resources

   Wrap the resource in try (Resource r = ...) { } to ensure it is always closed, even when exceptions occur.