IOException

Why This Happens

IOException is the general exception for failed I/O operations including file reading/writing, network communication, and stream processing. The specific message varies. Common causes include closed streams, broken network connections, full disks, and permission issues.

The Problem

OutputStream out = new FileOutputStream("output.txt");
out.close();
out.write("hello".getBytes()); // IOException: Stream closed

The Fix

try (OutputStream out = new FileOutputStream("output.txt")) {
    out.write("hello".getBytes());
} // Automatically closed after use

Step-by-Step Fix

1. 1

   Identify the I/O operation

   Read the exception message and stack trace to find which specific I/O operation failed and why.

2. 2

   Check resource lifecycle

   Verify that streams, connections, and readers are not closed prematurely or used after closing.

3. 3

   Use try-with-resources

   Wrap I/O operations in try-with-resources to ensure proper opening, usage, and automatic closing.