<<java并发编程实践>>之复合操作加锁策略

public class UnSafeOperation {   //直接使用this加锁public synchronized String get(Vector<String> vector) {if (vector.isEmpty()) {return null;}int index = vector.size() - 1;return vector.get(index);}   //对vector加锁public String get1(Vector<String> vector) {synchronized (vector) {if (vector.isEmpty()) {return null;}int index = vector.size() - 1;return vector.get(index);}}public synchronized void delete(Vector<String> vector) {int index = vector.size() - 1;vector.remove(index);}public synchronized void delete1(Vector<String> vector) {synchronized (vector) {int index = vector.size() - 1;vector.remove(index);}}public static void main(String[] args) {final Vector<String> vector = new Vector<String>();vector.add("chneliang");final UnSafeOperation unSafe = new UnSafeOperation();new Thread() {public void run() {unSafe.get(vector);}}.start();unSafe.delete(vector);}}

实现对Vector的修改,如果不使用加锁控制,这样的复合操作，会导致发生错误。但是如果加锁,是直接像get()方法这样，还是对修改的对象加锁,其实很明显,如果我们直接对this加锁,会导致该类中的其他同步方法受到阻塞,锁的粒度太大,如果我们仅仅只是对要修改的对象加锁,就不会有这样的问题。
初次学习并发,发现涉及锁的策略,也并不是那么简单的直接用一个synchronized关键字就能搞定的。