static final int SIZE = 10000000;

public static void main(String[] args) {

System.out.println("Time of serial method: " + countArraySerial());

System.out.println("Time of parallel method: " + countArrayParallel());

}

private static long countArraySerial() {

float[] arr = new float[SIZE];

for (int i=0; i<SIZE; i++)

arr[i] = 1;

long beginTiming = System.currentTimeMillis();

for (int i=0; i<SIZE; i++) {

arr[i] = (float)(arr[i] * sin(0.2f+i/5.0f) * cos(0.2f+i/5.0f) * cos(0.4f+i/2.0f));

}

return System.currentTimeMillis() - beginTiming;

}

private static long countArrayParallel() {

float[] arr = new float[SIZE];

float[] a1 = new float[SIZE/2];

float[] a2 = new float[SIZE/2];

int h = SIZE/2;

for (int i=0; i<SIZE; i++)

arr[i] = 1;

long beginTiming = System.currentTimeMillis();

System.arraycopy(arr,0,a1,0,h);

System.arraycopy(arr,h,a2,0,h);

//создаем пул с двумя потоками

ExecutorService executor = Executors.newFixedThreadPool(2);

List<Future<float[]>> list = new ArrayList<>();

CallableCounter thread1 = new CallableCounter(a1,0);

CallableCounter thread2 = new CallableCounter(a2,1);

//вычисляем результаты свободными потоками

list.add(executor.submit(thread1));

list.add(executor.submit(thread2));

//соединяем результаты

try {

System.arraycopy(list.get(0).get(),0,arr,0,h);

System.arraycopy(list.get(1).get(),0,arr,h,h);

} catch (InterruptedException | ExecutionException e) {

e.printStackTrace();

}

executor.shutdown();

return System.currentTimeMillis() - beginTiming;

}