How do you keep the console from closing after the program is done?

Question

How do you keep the console from closing after the program is done in Java?

Answer 1

readLine() waits until you press a key:

public static void main (String[] args) throws IOException {
    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
    in.readLine();
}

Answer 2

The simplest way I've found:

Scanner scanner = new Scanner(System.in); 
scanner.nextLine();

Answer 3

There are several ways to achieve this.

• You can request the user for input at the end of your main method.

• You can create and start a thread. Deamon threads are automatically closed when your main method finishes. However non-deamon threads will keep your application alive until they are finished.

• Or just call wait on an object.

I'm not sure though, why you would want to keep an application alive, if it's not doing anything anymore.

Using a non-deamon thread:

// example of an application that never closes.
public static void main(String[] args) {
    new Thread(new Runnable() {
        @Override
        public synchronized void run() {
            for(;;)
                try {
                    wait();
                } catch (InterruptedException e) {
                }
        }
    }).run();
}

Calling wait on an object:

public static void main(String[] args)throws Exception {
    Object o = new Object();
    synchronized (o) {
        o.wait();
    }
}

Answer 4

Firing empty Scanner input at the end of the code works each time, because the scanner waits for user to press ENTER.

//to-do your code
Scanner.nextLine();

Shame Java does not have inbuilt wait or pause command for the console apps.

EDIT: If you want to construct Scanner, you do it like this:

Scanner scanner = new Scanner(System.in); 
scanner.nextLine();

System.in is parameter that tells the scanner which input stream to use.