边遍历边删除，if判断里面size--，i--
public void finishOne(ClassactivityClass){
int size =mActivities.size();
for (int i =0; i < size; i++) {
Activity activity =mActivities.get(i);
if (activity.getClass().getCanonicalName().equals(activityClass.getCanonicalName())) {
mActivities.remove(i);
activity.finish();
i--;
size--;
}
}
}
