代码如下：
[code="java"]
public class SomeObj {
public void print(int i){
System.out.println(Thread.currentThread().getName()+DateHelper.getNow()+ " " + i);
try {
wait(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
public
class ThreadA extends Thread{
private SyncTest st;
public ThreadA(SyncTest syncTest){
this.st=syncTest;
}
public void run(){
st.methodA();
}
}
public class SyncTest {
private volatile int i;
public static void main(String[] args) throws Exception {
new SyncTest().startUp();
}
public void startUp(){
for (int a = 0; a < 10; a++) {
new ThreadA(this).start();
}
}
private SomeObj obj = new SomeObj();
public void methodA() {
synchronized (obj) {
obj.print(i);
System.out.println(Thread.currentThread().getName()+DateHelper.getNow() + " god is a girl");
i++;
}
}
}
[/code]
synchronized (obj) { 运行结果显示，同步代码块并没有被锁住，而把这行代码的obj替换成this或者随便其他的instance对象，都能锁住代码块。求解？
