5：实现一个ATM模拟类Bank，它使用subtractAmount()方法对账户的余额进行扣除，实现Runabl接口。
具体代码：
1 public class Bank implements Runnable { 2 3 /** 4 * The account affected by the operations 5 */ 6 private Account account; 7 8 /** 9 * Constructor of the class. Initializes the account 10 * @param account The account affected by the operations 11 */ 12 public Bank(Account account) { 13 this.account=account; 14 } 15 16 17 /** 18 * Core method of the Runnable 19 */ 20 public void run() { 21 for (int i=0; i<100; i++){ 22 account.subtractAmount(1000); 23 } 24 } 25 26 } |
6：实现公司模拟类，调用addAmount()方法进行存钱，实现Runabl接口。
具体代码：
1 public class Company implements Runnable { 2 3 /** 4 * The account affected by the operations 5 */ 6 private Account account; 7 8 /** 9 * Constructor of the class. Initializes the account 10 * @param account the account affected by the operations 11 */ 12 public Company(Account account) { 13 this.account=account; 14 } 15 16 /** 17 * Core method of the Runnable 18 */ 19 public void run() { 20 for (int i=0; i<100; i++){ 21 account.addAmount(1000); 22 } 23 } |
7：在主方法中调用测试：通过线程的join方法，在存期那，取钱线程模拟完毕后打印出结构。
1 public class Main { 2 3 /** 4 * Main method of the example 5 * @param args 6 */ 7 public static void main(String[] args) { 8 // Creates a new account ... 9 Account account=new Account(); 10 // an initialize its balance to 1000 11 account.setBalance(1000); 12 13 // Creates a new Company and a Thread to run its task 14 Company company=new Company(account); 15 Thread companyThread=new Thread(company); 16 // Creates a new Bank and a Thread to run its task 17 Bank bank=new Bank(account); 18 Thread bankThread=new Thread(bank); 19 20 // Prints the initial balance 21 System.out.printf("Account : Initial Balance: %f\n",account.getBalance()); 22 23 // Starts the Threads 24 companyThread.start(); 25 bankThread.start(); 26 27 try { 28 // Wait for the finalization of the Threads 29 companyThread.join(); 30 bankThread.join(); 31 // Print the final balance 32 System.out.printf("Account : Final Balance: %f\n",account.getBalance()); 33 } catch (InterruptedException e) { 34 e.printStackTrace(); 35 } 36 } 37 } |
结果,相同时间内，存与取执行后应该是相等的。如果我们在方法中不去使用synchronized关键字，那么得出的结果就不对了。
Account : Initial Balance: 1000.000000
Account : Final Balance: 1000.000000
