Java Timer/TimerTask was used for scheduling tasks which requires to be executed at certain interval, frequency etc. Java 5 introduced the concept of thread pool for limiting number of threads executing at a particular point of time. Creating a thread consumes a significant amount of memory and hence limiting the number of threads via thread pool will give better performance and saves memory.
Java 5 documentation recommends to use ScheduledExecutorService for creating scheduler jobs. This is further simpler implementation and doesn't require subclassing as was required in case of a TimerTask.
Example scheduler using ScheduledExecutorService is as follows:
package
com.prasune.test.concurrent;
import java.util.Date;
import
java.util.concurrent.Executors;
import
java.util.concurrent.ScheduledExecutorService;
import
java.util.concurrent.ScheduledFuture;
import
java.util.concurrent.TimeUnit;
public class SchedulerService {
public static void main(String[] args) {
ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(5);
Runnable command = new Runnable() {
@Override
public void run() {
System.out.println("Executing
the scheduler " + new Date());
}
};
// Creates and executes a periodic action
that becomes enabled first
// after the given initial delay, and
subsequently with the given period
final ScheduledFuture
timerHandle =
scheduler.scheduleAtFixedRate(command, 5, 60, TimeUnit.SECONDS);
// Stop command execution after one hour
Runnable cancelTimerCommand = new Runnable() {
public void run() {
timerHandle.cancel(true);
}
};
scheduler.schedule(cancelTimerCommand, 60 * 60,
TimeUnit.SECONDS);
}
}
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