Can we execute the java program after calling System.exit(0)

Approach#1

Using ShutdownHook

class MyThread extends Thread { 

     public void run() { 

           System.out.println("After System exit call.");

     } 

} 

public class TestSystemExit { 

     public static void main(String[] args)throws Exception { 

           Runtime runtime = Runtime.getRuntime(); 

          

           runtime.addShutdownHook(new MyThread()); 

           System.out.println("Before System exit call.");

           System.exit(0); 

          

     } 

}

Output:

Before System exit call.

After System exit call.

What is ShutDownHook?

Shutdown Hooks are a special construct that allow developers to plug in a piece of code to be executed when the JVM is shutting down.

Approach#2

We can achieve it by overriding the checkExit method of SecurityManager class.

import java.security.Permission;

public class SystemExitBreaked {

     public static void main(String[] args) {

           System.setSecurityManager(new SecurityManager() {

                @Override

                public void checkPermission(Permission perm) {

                }

                @Override

                public void checkExit(int status) {

                     //throw new SecurityException(); // Line 10

                }

           });

           checkSystemExit();

     }

     public static void checkSystemExit() {

           System.out.println("Before System.exit(0)");

           try {

                System.exit(0);

           } catch (SecurityException se) {

                System.out.println("Inside the catch block !");

           }

           System.out.println("After System.exit(0)");

     }

}

Output: Before System.exit(0)

Now uncomment the line 10 i.e throw new SecurityException().

The new output will be:

Output:

Before System.exit(0)

Inside the catch block!

After System.exit(0)