Test to show how iterating on a synchronized collection causes exception if another thread modifies it

gistfile1.java

package com.foo;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CountDownLatch;

public class SynchronizedCollectionIteration {
    public static void main(String[] args) {
        final CountDownLatch latch = new CountDownLatch(1);
        List<Integer> list = new ArrayList<Integer>();

        for (int i = 0; i < 1_000_000; i++) {
            list.add(i);
        }

        final List<Integer> synchronizedList = Collections.synchronizedList(list);
        Runnable iteration = new Runnable() {
            @Override
            public void run() {
                try {
                    latch.await();
                    for (Integer i : synchronizedList) {
                        System.out.println("i = " + i);
                    }
                }
                catch (InterruptedException e) {
                    // stop running
                }
            }
        };

        Runnable modification = new Runnable() {
            @Override
            public void run() {
                try {
                    latch.await();
                    while (!synchronizedList.isEmpty()) {
                        synchronizedList.remove(0);
                    }
                }
                catch (InterruptedException e) {
                    // stop running
                }
            }
        };

        Thread t1 = new Thread(iteration);
        Thread t2 = new Thread(modification);

        t1.start();
        t2.start();

        latch.countDown();
    }
}