Print "hello world" every X seconds

Question

Lately I've been using loops with large numbers to print out Hello World:

int counter = 0;  while(true) {     //loop for ~5 seconds     for(int i = 0; i < 2147483647 ; i++) {         //another loop because it's 2012 and PCs have gotten considerably faster :)         for(int j = 0; j < 2147483647 ; j++){ ... }     }     System.out.println(counter + ". Hello World!");     counter++; } 

I understand that this is a very silly way to do it, but I've never used any timer libraries in Java yet. How would one modify the above to print every say 3 seconds?

Answer 1

If you want to do a periodic task, use a ScheduledExecutorService. Specifically ScheduledExecutorService.scheduleAtFixedRate

The code:

Runnable helloRunnable = new Runnable() {     public void run() {         System.out.println("Hello world");     } };  ScheduledExecutorService executor = Executors.newScheduledThreadPool(1); executor.scheduleAtFixedRate(helloRunnable, 0, 3, TimeUnit.SECONDS); 

Answer 2

You can also take a look at Timer and TimerTask classes which you can use to schedule your task to run every n seconds.

You need a class that extends TimerTask and override the public void run() method, which will be executed everytime you pass an instance of that class to timer.schedule() method..

Here's an example, which prints Hello World every 5 seconds: -

class SayHello extends TimerTask {     public void run() {        System.out.println("Hello World!");      } }  // And From your main() method or any other method Timer timer = new Timer(); timer.schedule(new SayHello(), 0, 5000);