[Ch15] Adding AtomicInteger

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.atomic.AtomicInteger;

public class LostUpdate {

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

    ExecutorService pool = Executors.newFixedThreadPool(30);

    Balance balance = new Balance();

    AtomicBalance balance = new AtomicBalance();

    for (int i = 0; i < 1000; i++) {

      pool.execute(() -> balance.increment());

    }

class Balance {

  int balance = 0;

  // add synchronized here to see it work properly

  public void increment() {

    balance++;

  }

}

class AtomicBalance {

  AtomicInteger balance = new AtomicInteger(0);

  public void increment() {

    balance.incrementAndGet();

  }

}