МЭЙН:

public class Main {

    private static Thread[] tPool;
    static TaskQueue tq;

    public static void main(String[] args) throws InterruptedException {

        tq = new TaskQueue();
        tq.push(new MyTask(1,50));
        tq.push(new MyTask(5,30));
        tq.push(new MyTask(1,4));
        tq.push(new MyTask(2,15));
        tq.push(new MyTask(1,50));
        tq.push(new MyTask(5,30));
        tq.push(new MyTask(1,4));
        tq.push(new MyTask(2,15));


        tPool = new Thread[2];

        for (int i=0; i < 2; i++) {
            tPool[i] = new Thread(){

                @Override
                public void run() {
                    MyTask task;
                    while(!tq.isEndOfQueue()) {
                        synchronized(tq) {
                            if((task = tq.pop()) != null){
                                for(int i = task.getStart(); i <= task.getEnd(); i++)
                                if(isSimple(i))
                                    task.addAnswer(i);
                            task.setDone(true);
                            tq.push(task);
                            }
                        }
                    }
                 }
              };
              tPool[i].start();
              tPool[i].join();
            }

        tq.showResult();
    }

    public static boolean isSimple(final int n) {
        for(int i=2;i<=Math.sqrt(n);i++)
            if(n%i==0)
                return false;
        return true;
    }
}






ОЧЕРЕДЬ:

import java.util.LinkedList;


public class TaskQueue {

    private LinkedList<MyTask> list;

    public TaskQueue() {
        list = new LinkedList<>();
    }

    public MyTask pop() {
        synchronized(list) {
            if(!list.getFirst().isDone())
            return list.removeFirst();
        return null;
        }
    }

    public void push(MyTask task) {
        synchronized(list) {
            list.addLast(task);
        }
    }

    public void showResult() {
        synchronized(list) {
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i).getResult().toString());
            }
        }
    }

    public boolean isEndOfQueue() {
        synchronized(list) {
            return this.list.getFirst().isDone();
        }
    }
}



ЗАДАНИЕ:

import java.util.ArrayList;

public class MyTask {
    private boolean done;
    private int start;
    private int end;
    private ArrayList <Integer> answers;

    public MyTask(int start, int end) {
        this.start = start;
        this.end = end;
        this.answers = new ArrayList<>();
        this.setDone(false);
    }

    public ArrayList<Integer> getResult() {
        return answers;
    }

    public boolean isDone() {
        return done;
    }

    public void setDone(boolean done) {
        this.done = done;
    }

    public int getStart() {
        return this.start;
    }
    public int getEnd() {
        return this.end;
    }

    public void addAnswer(final int val) {
        this.answers.add(val);
    }
}