Here's my following code:
ExecutorService executor = Executors.newFixedThreadPool(5);
executor.submit(new Runnable() {
public void run() {
for (int i = 0; i < 5; i++) {
System.out.println("Start"+" "+Thread.currentThread().getName());
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("End!"+" "+Thread.currentThread().getName());
}
}
});
executor.shutdown();
executor.awaitTermination(1, TimeUnit.SECONDS);
Here's my output:
Start pool-1-thread-1
End! pool-1-thread-1
Start pool-1-thread-1
End! pool-1-thread-1
Start pool-1-thread-1
End! pool-1-thread-1
Start pool-1-thread-1
End! pool-1-thread-1
Start pool-1-thread-1
End! pool-1-thread-1
My understanding is that in my code there're 5
threads in FixedThreadPool
. So when I run my code, it's supposed to output all 5
threads, right? Or Am I misunderstanding something?
In my output thread-1
starts and end everytime but isn't it supposed to output all 5
threads when it loops in for
loop? Cause if only 1 thread
is doing the task
then why do we even need 5 threads
? Is there any way all 5
threads can output on the console?(I'm a newbie)
You are posting only one Runnable
so your ExecutorService
runs one task. It will use only one thread. To use multiple threads you must call submit
multiple times or you can call invokeAll
with a Collection
of runnables.
EDIT
Something like this:
public void test() {
int numberOfThreads = 5;
ExecutorService executorService = Executors.newFixedThreadPool(numberOfThreads);
for(int i=0; i<numberOfThreads; i++){
executorService.submit(createRunnable());
}
}
private Runnable createRunnable() {
return new Runnable() {
@Override
public void run() {
for (int i = 0; i < 5; i++) {
System.out.println("Start" + " " + Thread.currentThread().getName());
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("End!" + " " + Thread.currentThread().getName());
}
}
};
}
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