Java thread synchronization mechanism revealed

Java thread synchronization mechanism includes: synchronized keyword: ensure that only one thread executes the specified method or code block at the same time. ReentrantLock: Reentrant lock, allowing multiple threads to acquire the same lock. Semaphore: Counter, limits the number of threads that can acquire locks at the same time. Atomic variable: A thread-safe variable class that updates variable values ​​synchronously. By using these mechanisms, the integrity of data in a multi-threaded environment can be guaranteed and unpredictable errors can be prevented.

Java thread synchronization mechanism revealed

Introduction

In a multi-threaded environment, concurrent execution of threads may lead to unpredictable errors. In order to ensure data consistency, appropriate thread synchronization mechanisms need to be adopted. This article will delve into the thread synchronization mechanism in Java and provide a practical case.

Thread synchronization mechanism

Java provides a variety of thread synchronization mechanisms, including:

• synchronized keyword: Apply the keyword synchronized For methods or code blocks, it is guaranteed that only one thread executes the method or code block at the same time.
• ReentrantLock: A reentrant lock that allows multiple threads to acquire the same lock, but the same thread can acquire it multiple times.
• Semaphore: A counter that limits the number of threads that acquire the lock at the same time.
• Atomic variable: A thread-safe variable class that can update variable values ​​​​synchronously.

Practical case

Consider the following simple bank account class:

public class BankAccount {
    private int balance;

    public void deposit(int amount) {
        balance += amount;
    }

    public void withdraw(int amount) {
        if (balance >= amount) {
            balance -= amount;
        }
    }
}

Without thread synchronization, it is possible to access this account in a multi-threaded environment Can cause unpredictable errors. To solve this problem, we can use the synchronized keyword to synchronize access to the account balance:

public class BankAccount {
    private int balance;

    public synchronized void deposit(int amount) {
        balance += amount;
    }

    public synchronized void withdraw(int amount) {
        if (balance >= amount) {
            balance -= amount;
        }
    }
}

By using synchronized, we ensure that only one thread can access the account balance at any time, thereby ensuring data integrity.

Conclusion

Thread synchronization mechanism is crucial to multi-threaded programming and helps prevent data races and unpredictable errors. Java provides a wide range of thread synchronization options, allowing developers to choose the mechanism that best suits their specific needs.

The above is the detailed content of Java thread synchronization mechanism revealed. For more information, please follow other related articles on the PHP Chinese website!