仅当所有线程在访问该集合前都锁定该对象时，同步才有效。

Synchronization is effective only if all threads lock this object before accessing the collection.

youdao

唯有在存取集合之前，将所有执行绪都锁定物件，同步处理才会有效。

Synchronization is effective only if all threads lock the object before accessing the collection.

youdao

唯有在存取集合之前，将所有执行绪都锁定物件，同步处理才会有效。

Synchronization is effective only if all threads lock the object before accessing the collection.

youdao