Chapter 30 Exercise 8, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

30.8 (Account synchronization) Rewrite Listing 30.6, ThreadCooperation.java,
using the object’s wait() and notifyAll() methods.

import java.util.concurrent.*;

public class Exercise08 {
 private static Account account = new Account();

 public static void main(String[] args) {
  // Create a thread pool with two threads
  ExecutorService executor = Executors.newFixedThreadPool(2);
  executor.execute(new DepositTask());
  executor.execute(new WithdrawTask());
  executor.shutdown();

  System.out.println("Thread 1\t\tThread 2\t\tBalance");
 }

 public static class DepositTask implements Runnable {
  @Override
  // Keep adding an amount to the account
  public void run() {
   try { // Purposely delay it to let the withdraw method proceed
    while (true) {
     account.deposit((int) (Math.random() * 10) + 1);
     Thread.sleep(1000);
    }
   } catch (InterruptedException ex) {
    ex.printStackTrace();
   }
  }
 }

 public static class WithdrawTask implements Runnable {
  @Override
  // Keep subtracting an amount from the account
  public void run() {
   while (true) {
    account.withdraw((int) (Math.random() * 10) + 1);
   }
  }
 }

 // An inner class for account
 private static class Account {

  private int balance = 0;

  public int getBalance() {
   return balance;
  }

  public synchronized void withdraw(int amount) {
   try {
    while (balance < amount) {
     System.out.println("\t\t\tWait for a deposit");
     this.wait();
    }

    balance -= amount;
    System.out.println("\t\t\tWithdraw " + amount + "\t\t" + getBalance());
   } catch (InterruptedException ex) {
    ex.printStackTrace();
   }
  }

  public synchronized void deposit(int amount) {
   balance += amount;
   System.out.println("Deposit " + amount + "\t\t\t\t\t" + getBalance());
   notifyAll();
  }
 }
}