Java中的并发控制问题案例研究

原创分手后的思念是犯贱 2024-10-07 19:21 66阅读 0赞

在Java中，由于多线程的存在，很容易出现并发控制的问题。以下将通过几个案例进行深入研究：

1. **死锁**：当两个或更多的线程因争夺资源而造成的一种互相等待的现象时，就可能出现死锁。

例如：
   ```java
   class BankAccount {
       Lock lock;
       int balance;

BankAccount() {
           lock = new Lock();
           balance = 0;
       }

void deposit(int amount) throws InterruptedException {
           lock.lock();
           try {
               balance += amount;
               System.out.println("Deposit successful, balance: " + balance);
           } finally {
               lock.unlock();
           }
       }

void withdraw(int amount) throws InterruptedException {
           lock.lock();
           try {
               if (amount > balance) {
                   throw new IllegalArgumentException("Withdrawal exceeds current balance.");
                 }
               balance -= amount;
               System.out.println("Withdrawal successful, balance: " + balance);
           } finally {
               lock.unlock();
           }
       }
   }
   ```

2. ****线程安全的类****：在Java中，设计线程安全的类需要通过锁机制来控制并发。

例如：
   ```java
   class SafeCounter {
       private int count;
       private Lock lock;

SafeCounter() {
           count = 0;
           lock = new Lock();
       }

synchronized int getCount() {
           return count;
       }

synchronized void increment() throws InterruptedException {
           lock.lock();
           try {
               count++;
               System.out.println("Increment successful, count: " + count);
           } finally {
               lock.unlock();
           }
       }

synchronized void decrement() throws InterruptedException {
           lock.lock();
           try {
               if (count > 0) {
                   count--;
                   System.out.println("Decrement successful, count: " + count);
                 } else {
                   throw new IllegalArgumentException("Cannot decrement count to zero.");
                 }
           } finally {
               lock.unlock();
           }
       }
   }
   ```

以上案例都是Java中常见的并发控制问题，理解和解决这些问题对于编写高效并发程序至关重要。