[Ch15] Ryan and Monica's bank account statements that throws a concurrentmodificationexception

    BankAccountStatement account = new BankAccountStatement();

    RyanAndMonicaStatementJob ryan = new RyanAndMonicaStatementJob("Ryan", account);

    RyanAndMonicaStatementJob monica = new RyanAndMonicaStatementJob("Monica", account);

    ExecutorService executor = Executors.newFixedThreadPool(2);

    ExecutorService executor = Executors.newFixedThreadPool(4);

    executor.execute(ryan);

    executor.execute(monica);

    executor.execute(new Accountant(account));

    executor.execute(new Accountant(account));

    executor.shutdown();

    executor.awaitTermination(1, TimeUnit.MINUTES);

  }

  }

}

class Accountant implements Runnable {

  private final BankAccountStatement account;

  Accountant(BankAccountStatement account) {

    this.account = account;

  }

  @Override

  public void run() {

      System.out.println(account.getStatement());

  }

}

class BankAccountStatement {

  private final List<Withdrawal> statement = new ArrayList<>();

  public void makeWithdrawal(int amount, String name) {

    if (getBalance() >= amount) {

      System.out.println(name + " is about to withdraw");

      try {

        System.out.println(name + " is going to sleep");

        Thread.sleep(500);

      } catch (InterruptedException ex) {ex.printStackTrace();}

      System.out.println(name + " woke up.");

      withdraw(name, amount);

      System.out.println(name + " completes the withdrawal");

    statement.add(withdrawal);

  }

  public List<Withdrawal> getStatement() {

    return statement;

  }

}

class Withdrawal {

  public int getCurrentBalance() {

    return currentBalance;

  }

  @Override

  public String toString() {

    return "Withdrawal{" +

            "name='" + name + '\'' +

            ", amount=" + amount +

            ", currentBalance=" + currentBalance +

            '}';

  }

}