一个读写锁的例子

用的比较少, 做一个参考. 原文在 这里

public class Calculator {
    private int calculatedValue;
    private int value;
    private ReadWriteLock lock = new ReentrantReadWriteLock();
 
    public void calculate(int value) {
        lock.writeLock().lock();
        try {
            this.value = value;
            this.calculatedValue = doMySlowCalculation(value);
        } finally {
            lock.writeLock().unlock();
        }
    }
 
    public int getCalculatedValue() {
        lock.readLock().lock();
        try {
            return calculatedValue;
        } finally {
            lock.readLock().unlock();
        }
    }
 
    public int getValue() {
        lock.readLock().lock();
        try {
            return value;
        } finally {
            lock.readLock().unlock();
        }
    }
}