Shutdown Hook 

The JVM exits when System.exit method is invoked or when the last non daemon thread exits. When the virtual machine begins its shutdown sequence it starts the execution of registered shutdown hooks in some unspecified order. The shutdown hooks are useful to perform clean up activities.

File Name  :   com/bethecoder/tutorials/runtime/ShutdownHookTest.java  Author  :   Sudhakar KV Email  :   [email protected]

package com.bethecoder.tutorials.runtime; public class ShutdownHookTest {   public static void main(String[] args) throws Exception {          //Order of execution of hooks is unknown     for (int i = 0 ; i < 6 ; i ++ ) {       Runtime.getRuntime().addShutdownHook(getHook("HOOK#"+i));       }          System.out.println("Sleeping");     Thread.sleep(6000);     System.out.println("About to exit JVM");     System.exit(0);   }      public static Thread getHook(final String hookName) {          return new Thread() {             public void run() {         System.out.println("HookName : " + hookName);       }     };   }    }

Sleeping
About to exit JVM
HookName : HOOK#3
HookName : HOOK#5
HookName : HOOK#2
HookName : HOOK#1
HookName : HOOK#0
HookName : HOOK#4