One time task execution example, using schedule(TimerTask task, long delay)
public class OneTimeTask {
public static void main (String[] args) {
System.out.println("Main thread: " + Thread.currentThread());
Timer timer = new Timer();
final long start = System.currentTimeMillis();
timer.schedule(new TimerTask() {
@Override
public void run () {
System.out.print("Task invoked: " +
(System.currentTimeMillis() - start) + " ms");
System.out.println(" - " + Thread.currentThread());
timer.cancel();
}
}, 1000);
}
}
Fixed rate task example , using schedule(TimerTask task, long delay, long period)
public class FixedDelayTask {
private static int count;
public static void main (String[] args) {
System.out.println("Main thread: " + Thread.currentThread());
Timer timer = new Timer();
final long start = System.currentTimeMillis();
timer.schedule(new TimerTask() {
@Override
public void run () {
System.out.print("Task invoked: - " + (++count) + " - " +
(System.currentTimeMillis()
- start) + " ms");
System.out.println(" - " + Thread.currentThread());
}
}, 1000, 500);
}
}
Fixed Rate task example using method, scheduleAtFixedRate(TimerTask task, long delay, long period)
public class FixedRateTask {
private static int count;
public static void main (String[] args) {
System.out.println("Main thread: " + Thread.currentThread());
Timer timer = new Timer();
final long start = System.currentTimeMillis();
timer.scheduleAtFixedRate(new TimerTask() {
@Override
public void run () {
System.out.print("Task invoked - " + (++count) + " - " +
(System.currentTimeMillis()
- start) + " ms");
System.out.println(" - " + Thread.currentThread());
}
}, 1000, 500);
}
}
Using schedule(TimerTask task, long delay), submitting multiple tasks.
public class OneTimeMultipleTasks {
public static void main (String[] args) {
System.out.println("Main thread: " + Thread.currentThread());
Timer timer = new Timer();
final long start = System.currentTimeMillis();
final TimerTask timerTask1 = new TimerTask() {
@Override
public void run () {
System.out.print("Task1 invoked: " +
(System.currentTimeMillis()
- start) + " ms");
System.out.println(" - " + Thread.currentThread());
try {
/*The task should finish quickly, otherwise it will delay other tasks, here
we are simulating a long running task to see the issue, if you remove this
the second task will run at its provided initial delay*/
Thread.sleep(1500);
} catch (InterruptedException e) {
e.printStackTrace();
}
/*don't call cancel here cause it will
terminate timer and second task won't run.*/
//timer.cancel();
}
};
final TimerTask timerTask2 = new TimerTask() {
@Override
public void run () {
System.out.print("Task2 invoked : " +
(System.currentTimeMillis()
- start) + " ms");
System.out.println(" - " + Thread.currentThread());
timer.cancel();
}
};
timer.schedule(timerTask1, 1000);
/*
second submission of the same task will cause
java.lang.IllegalStateException: Task already scheduled or cancelled
timer.schedule(timerTask1, 2000);
*/
timer.schedule(timerTask2, 2000);
}
}
