How to Resolve java.io.IOException: Connection Refused Messages in Logcat

What does it mean when Logcat shows 'java.io.IOException: Connection refused' messages?

// Example of a connection attempt that may cause IOException:
try {
    Socket socket = new Socket("localhost", 8080);
} catch (IOException e) {
    e.printStackTrace();  // This may print the 'Connection refused' message
}

The 'java.io.IOException: Connection refused' error occurs when your application attempts to connect to a server that is not accepting connections on the specified IP address and port. Understanding this error will help you effectively troubleshoot it.

// Code to check server connection
try {
    Socket socket = new Socket("localhost", 8080);
    System.out.println("Connection successful!");
} catch (IOException e) {
    System.out.println("Connection failed: " + e.getMessage());
}

Causes

• The server application is not running.
• The server is not listening on the specified port.
• A firewall is blocking the connection.
• An incorrect IP address or hostname is specified.

Solutions

• Ensure that the server application is running on your local machine or a remote server.
• Verify that the server is configured to listen on the correct port (e.g., port 8080).
• Check firewall settings to ensure that they allow traffic through the specified port.
• Confirm that the IP address or hostname used in the connection attempt is correct.

Mistake: Assuming the server is running without checking.

Solution: Always verify that the server application is actively running.

Mistake: Using the wrong IP address or port.

Solution: Double-check the configuration settings for correctness.

Mistake: Not considering firewall rules that could block the connection.

Solution: Review and adjust firewall settings if necessary.