Runtime addShutdownHook(Thread) in Java

addShutdownHook(Thread): This method is available in the java.lang.Runtime class of Java.

Syntax:

void java.lang.Runtime.addShutdownHook(Thread hook)

This method takes one argument. This method registers a new virtual machine shutdown hook.

The Java virtual machine shuts down in response to two kinds of events:

1. The program exits normally, when the last non-daemon thread exits or when the exit (equivalently, System.exit) method is invoked.

2. The virtual machine is terminated in response to a user interrupt, such as typing ^C, or a system-wide event, such as user log off or system shutdown.

Parameters: One parameter is required for this method.

hook: An initialized but unstarted Thread object.

Throws:

1. IllegalArgumentException - If the specified hook has already been registered, or if it can be determined that the hook is already running or has already been run.

2. IllegalStateException - If the virtual machine is already in the process of shutting down.

3. SecurityException - If a security manager is present and it denies RuntimePermission("shutdownHooks").

Approach

Java

package com.Runtime;

public class RuntimeaddShutdownHook {
    public static void main(String[] args) {

        Runtime runtime = Runtime.getRuntime();

        Thread hook = new Thread();
        runtime.addShutdownHook(hook);
        System.out.println("Successfully adds shutdown hook");
    }
}

Output:

Successfully adds shutdown hook

Some other methods of Runtime

addShutdownHook(Thread): This method registers a new virtual machine shutdown hook.

availableProcessors(): This method returns the number of processors available to the Java virtual machine.

exec(String): This method executes the specified string command in a separate process.

exec(String[]): This method executes the specified command and arguments in a separate process.

exec(String, String[]): This method executes the specified string command in a separate process with the specified environment.

exec(String[], String[]): This method executes the specified command and arguments in a separate process with the specified environment.

exec(String, String[], File): This method executes the specified string command in a separate process with the specified environment and working directory.

exec(String[], String[], File): This method executes the specified command and arguments in a separate process with the specified environment and working directory.

gc(): This method runs the garbage collector in the Java Virtual Machine.

Runtime.getRuntime(): This method returns the runtime object associated with the current Java application.

halt(int): This method forcibly terminates the currently running Java virtual machine.

load(String): This method loads the native library specified by the filename argument.

loadLibrary(String): This method loads the native library specified by the libname argument.

maxMemory(): This method returns the maximum amount of memory that the Java virtual machine will attempt to use.

removeShutdownHook(Thread): This method De-registers a previously registered virtual machine shutdown hook.

runFinalization(): This method runs the finalization methods of any objects pending finalization.

version(): This method returns the version of the Java Runtime Environment as a Version.

exit(int): This method terminates the currently running Java virtual machine by initiating its shutdown sequence. This method never returns normally.

freeMemory(): This method returns the amount of free memory in the Java Virtual Machine.

totalMemory(): This method returns the total amount of memory in the Java virtual machine.