Thread Producer and Consumer

Question

Hi
I have an array that keeps Integer into it. what is wrong with this problem i cant fix it. Thread Consumer never start.
Producer class: Putting nr 1 to 50 int into array eg. 1-2-3-4-5-6-7-8-9-10.....
Consumer class : removing 50 down to nr 10 from array 50-49-48-47...
Main Class : Threads creator and starter.
How can i let Thread P start before C. and when P is finnish it call C, and then C when its done it wakes up P and running like that for life. HOWWW Plz help
MAIN CLASS:
import java.util.ArrayList;
public class Main {
static ArrayList<Integer> list = new ArrayList<>();
public static void main(String[] args) {
Thread p = new Thread(new Producer());
Thread c = new Thread(new Consumer());
p.start();
c.start();
PRODUCER CLASS:
public class Producer extends Main implements Runnable{
@Override
public void run() {
while (true) {
// Tilføjer cornflakes til arrayListen hvis < 10
if (list.size() <= 10) {
for (int i = list.size(); i < 50; i++) {
list.add(i);
System.out.println("p : " + list.size());
try {
Thread.sleep(100);
} catch (InterruptedException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}// end Forloop
}// end if
}// end while
Consumer CLASS
public class Consumer extends Main implements Runnable {
@Override
public synchronized void run() {
while (true) {
// Tilføjer cornflakes til arrayListen hvis < 10
for (int i = list.size(); i > 10; i--) {
list.remove(i);
System.out.println("c : " + i);
try {
Thread.sleep(100);
} catch (InterruptedException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}// end Forloop
}// end while
}

Answer 1

That's a reason for failure in general by the way - trying to do stuff without understanding stuff. Its best avoided in the future - first learn and learn well, then code. Then when you have problem with said code, come here and ask for help. Not before that, a forum is not a personal information service or substitute teacher.