如图，java 在判断的时候，既然不等于null，为什么还要判断size大于0？不等于null肯定大于0呀？

Question

if (passengerList!=null&&passengerList.size()>0) {

} else {

}

Answer 1

When list==null, the system reports a null pointer exception when list.size()>0 is executed.