PriemGetallenRunnable.java

package hfdst4;
import java.util.*;
import java.util.concurrent.*;

class PriemZoekerRunnable implements Runnable {
    protected int start,einde;
    protected ArrayList<Integer> r;
    public PriemZoekerRunnable(int start, int einde, ArrayList<Integer> r) {
        this.start = start;
        this.einde = einde;
        this.r = r;
        System.out.println("Priemdraad: #"+start+" -> "+ einde+" aangemaakt !");
    }
    @Override
    public void run() {
        for (int n = start; n <= einde; n++) {
            if (n >= 2) {
                boolean flag = true;
                for (int i = 2; i <= Math.sqrt(n); i++) {
                    if (n%i == 0) {
                        flag = false;
                        break;
                    }
                }
                if (flag == true) {
                    // System.out.println("Priemgetal: " + n);
                    r.add(n);
                }
            }
        }
    }
}

class TestPriemRunnable {
    public static void main(String[] args) {
        int N = 1000;
        int nTaken = 10;
        int interval = N/nTaken;
        ArrayList[] list = new ArrayList[nTaken];
        ExecutorService e = Executors.newFixedThreadPool(nTaken);

        for (int i = 0; i < nTaken; i++) {
            list[i] = new ArrayList();
            e.execute(new PriemZoekerRunnable(i*interval, (i+1)*interval, list[i]));
        }
        e.shutdown();

        try {
            e.awaitTermination(100, TimeUnit.SECONDS);
        } catch(InterruptedException ex) {
            ex.printStackTrace();
        }

        for (ArrayList l : list)
            System.out.println(l);

    }
}