多线程访问同一个变量，不进行同步，会造成结果不一致。这里解决方案有很多，使用原子变量。加锁同步，使用synchronized同步。下面是一个lock demo，后面会分析lock实现原理。lock使用的是公平锁还是非公平锁等
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* Created by GuanXF on 2017/11/26.
*/
public class TestLock {
private static Lock lock = new ReentrantLock();
private static int count = 0 ;
// private static AtomicInteger count = new AtomicInteger(0);
public static void main(String[] args) throws InterruptedException {
Thread t1 = new Thread(task);
Thread t2 = new Thread(task1);
t1.start();
t2.start();
t1.join();
t2.join();
System.out.println("count = " + count);
}
static Runnable task1 = new Runnable() {
@Override
public void run() {
int index = 10000;
while(index > 0){
lock.lock();
count++;
lock.unlock();
// count.incrementAndGet();
index --;
}
}
};
static Runnable task = new Runnable() {
@Override
public void run() {
int index = 10000;
while(index > 0){
lock.lock();
count++;
lock.unlock();
// count.incrementAndGet();
index --;
}
}
};
}
