Java并发编程：线程同步和互斥问题实例

原创素颜马尾好姑娘i 2024-09-11 14:09 94阅读 0赞

在Java并发编程中，线程同步和互斥问题是常见的挑战。以下是一些实例：

1. **synchronized块/方法**：
   ```java
   // 示例1：synchronized修饰整个类
   class Counter {
       private int count = 0;
       
       public synchronized void increment() {
           count++;
       }
       
       public synchronized int value() {
           return count;
       }
   }
   
   // 示例2：synchronized修饰方法
   class BankAccount {
       private double balance = 0.0;
       
       public synchronized void deposit(double amount) {
           balance += amount;
       }
       
       public synchronized double withdraw(double amount) {
           if (amount > balance) {
               throw new InsufficientFundsException();
           }
           balance -= amount;
           return amount;
       }
   }
   ```

2. **使用wait()和notifyAll()**：
   ```java
   class Restaurant {
       private int tableCount = 10; // 初始化桌子数量
       
       public synchronized void reserveTable(int customerNum) { // 同步方法，防止多个线程同时进入
           if (tableCount > 0) { // 检查是否有空位
               System.out.println("Customer " + customerNum + " reserves table number " + tableCount);
               tableCount--; // 减少桌子数量
               notifyAll(); // 唤醒所有等待的线程
           } else {
               System.out.println("No tables available, customer " + customerNum + " cannot reserve a table.");
           }
       }
   }
   
   class Customer {
       public void visitRestaurant(Restaurant restaurant) {
           Restaurant.restaurant.reserveTable(1); // 顾客尝试预订
           try {
               Thread.sleep(2000); // 模拟耗时操作
           } catch (InterruptedException e) {
               e.printStackTrace();
           }
           System.out.println("Customer 1 leaves the restaurant.");
       }
   }
   
   public class RestaurantReservationExample {
       public static void main(String[] args) {
           Restaurant restaurant = new Restaurant();
           Customer customer = new Customer();

Thread customerThread = new Thread(customer::visitRestaurant, restaurant)); // 创建客户线程
           customerThread.start(); // 启动线程

// 这里可以添加更多的同步操作，以模拟更复杂的场景
       }
   }
   ```

这些实例展示了Java中如何通过synchronized关键字来实现线程同步和互斥。