[Ch15] Modernising the missing update code, it's out of order but I still...

package ch15;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

public class TestSyncTest {

  public static void main(String[] args) {

    TestSync job = new TestSync();

    Thread a = new Thread(job);

    Thread b = new Thread(job);

    a.start();

    b.start();

  }

    ExecutorService pool = Executors.newFixedThreadPool(2);

    Balance balance = new Balance();

    pool.execute(() -> incrementBalance50Times(balance));

    pool.execute(() -> incrementBalance50Times(balance));

    pool.shutdown();

  }

class TestSync implements Runnable {

  private int balance;

  public void run() {

  private static void incrementBalance50Times(Balance balance) {

    for (int i = 0; i < 50; i++) {

      increment();

      System.out.printf("Balance updated by %s. Balance is %d%n", Thread.currentThread().getName(), balance);

      balance.increment();

      System.out.printf("Balance updated by %s. Balance is %d%n", Thread.currentThread().getName(), balance.balance);

    }

  }

}

class Balance {

  int balance;

  public void increment() {

    int i = balance;

    balance = i + 1;

    balance++;

  }

}