有一种简单的方法可以保护变量只能由一个线程同时加入？

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class ThreadSafe {
    private int sharedVariable;

    private Lock lock = new ReentrantLock();
    private Condition condition = lock.newCondition();

    public void setValue(int value) {
        lock.lock();
        try {
            this.sharedVariable = value;
            condition.signalAll();
        } finally {
            lock.unlock();
        }
    }

    public int getValue() {
        lock.lock();
        try {
            while (sharedVariable == 0) {
                condition.await();
            }
            return sharedVariable;
        } catch (InterruptedException e) {
            e.printStackTrace();
            return -1;
        } finally {
            lock.unlock();
        }
    }
}