锁是否对同步执行相同的操作？

Question

假设我有一个线程安全的银行账户class看起来像这样

class BankAccount {

    private long balance;

    public synchronized long getBalance() {
        return balance;
    }

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

    public synchronized void withdraw(long amount) {
        balance -= amount;
    }
}

使用锁是否有同样的效果？

class BankAccount {

    private long balance;

    private final Lock lock = new ReentrantLock();

    public long getBalance() {
        try {
            lock.lock();
            return balance;
        } finally {
            lock.unlock();
        }
    }

    public void deposit(long amount) {
        try {
            lock.lock();
            balance += amount;
        } finally {
            lock.unlock();
        }
    }

    public void withdraw(long amount) {
        try {
            lock.lock();
            balance -= amount;
        } finally {
            lock.unlock();
        }
    }
}

Answer 1

是的。

ReentrantLock: A reentrant mutual exclusion Lock with the same basic behavior and semantics as the implicit monitor lock accessed using synchronized methods and statements, but with extended capabilities.

From the official documentation for reentrant locks

锁是否对同步执行相同的操作？

Does a lock do the same for synchronized?

java

locking

synchronized

reentrantlock