metodo newSingleThreadExecutor
È possibile ottenere un singolo pool di thread chiamando il metodo statico newSingleThreadExecutor () della classe Executors.
Sintassi
ExecutorService executor = Executors.newSingleThreadExecutor();
Dove il metodo newSingleThreadExecutor crea un esecutore che esegue una singola attività alla volta.
Esempio
Il seguente programma TestThread mostra l'utilizzo del metodo newSingleThreadExecutor in un ambiente basato su thread.
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
public class TestThread {
public static void main(final String[] arguments) throws InterruptedException {
ExecutorService executor = Executors.newSingleThreadExecutor();
try {
executor.submit(new Task());
System.out.println("Shutdown executor");
executor.shutdown();
executor.awaitTermination(5, TimeUnit.SECONDS);
} catch (InterruptedException e) {
System.err.println("tasks interrupted");
} finally {
if (!executor.isTerminated()) {
System.err.println("cancel non-finished tasks");
}
executor.shutdownNow();
System.out.println("shutdown finished");
}
}
static class Task implements Runnable {
public void run() {
try {
Long duration = (long) (Math.random() * 20);
System.out.println("Running Task!");
TimeUnit.SECONDS.sleep(duration);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
Questo produrrà il seguente risultato.
Produzione
Shutdown executor
Running Task!
shutdown finished
cancel non-finished tasks
java.lang.InterruptedException: sleep interrupted
at java.lang.Thread.sleep(Native Method)
at java.lang.Thread.sleep(Thread.java:302)
at java.util.concurrent.TimeUnit.sleep(TimeUnit.java:328)
at TestThread$Task.run(TestThread.java:39)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:662)