Capturing Ctrl C Interrupts in CLI Java Applications
In CLI Java applications, intercepting the Ctrl C signal (usually terminating the process) can be crucial for handling user input gracefully. This article addresses how to achieve this interception across multiple platforms.
Multi-Platform Solution
To intercept Ctrl C signals consistently across Linux, Solaris, and Windows, the recommended approach is using a SignalHandler. The sun.misc.SignalHandler class provides this functionality. By implementing SignalHandler#handle and registering it for the SIGINT signal, you can capture the interrupt and execute custom code.
Implementation
Here's an example of how to use a SignalHandler in Java:
<code class="java">import sun.misc.Signal; import sun.misc.SignalHandler; public class CtrlCHandler { public static void main(String[] args) { // Register a SignalHandler for SIGINT (Ctrl+C) Signal.handle(new Signal("INT"), new SignalHandler() { @Override public void handle(Signal signal) { // Custom shutdown code here System.out.println("Ctrl+C received, performing shutdown..."); Runtime.getRuntime().exit(0); } }); // Other application logic here... } }</code>
Note that this method will intercept the signal only as an intermediate step before the JVM shuts down completely, so it may not be suitable for all use cases.
Alternatively:
If using a SignalHandler is not feasible, consider using the Runtime.getRuntime().addShutdownHook method. This allows you to register a Thread that will be executed when the JVM is shutting down. Within this thread, you can handle the Ctrl C interrupt and perform any necessary cleanup or shutdown procedures.
<code class="java">Runtime.getRuntime().addShutdownHook(new Thread() { public void run() { // Custom shutdown code here System.out.println("JVM shutting down..."); } });</code>
These methods provide flexible solutions for intercepting Ctrl C signals in CLI Java applications, enabling you to handle user input gracefully and perform custom actions before process termination.
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