Java中带有线程的计时器

Question

I want to print this line:

System.out.println(Runtime.getRuntime().freeMemory());

every second. How to do it?

public class Hilo implements Runnable{    

    Thread t;
    String nombre;
    public  Hilo() {
         t = new Thread(this,"Hilo1");
         t.start();
    }

    @Override
    public void run() {
        System.out.println(Runtime.getRuntime().freeMemory());
    }
}

Answer 1

Use a java.util.Timer object.

A facility for threads to schedule tasks for future execution in a background thread. Tasks may be scheduled for one-time execution, or for repeated execution at regular intervals.

timer.schedule(new TimerTask() {
    @Override
    public void run() {
        System.out.println(Runtime.getRuntime().freeMemory());
    }
}, 0, 1000);

Answer 2

Another way to do it

ScheduledExecutorService ses = Executors.newSingleThreadScheduledExecutor();

ses.scheduleAtFixedRate(new Runnable() {
    @Override
    public void run() {
        System.out.println(Runtime.getRuntime().freeMemory());
    }
}, 0, 1, TimeUnit.SECONDS);

ses.shutdown();

Differences between java.util.timer and ScheduledExecutorService

1. ScheduledThreadPoolExecutor are not sensitive to changes in the system clock but Timer is.

2. Timer has only one execution thread, so long-running task can delay other tasks. ScheduledThreadPoolExecutor can be configured with any number of threads

Answer 3

By using below code you can print that want after every second

        timer.schedule(new TimerTask() {
           @Override
           public void run() {
                System.out.println(Runtime.getRuntime().freeMemory());
               }
              }, 0, 1000);

    }