Now I can code the behavior for the pop method, which ensures that if the stack is logically empty, an exception will be thrown.

现在我可以为pop方法编写行为，即确保当栈在逻辑上为空时，抛出一个异常。

youdao

In this case, ensuring that pop throws an exception if push hasn't been called (or logically, if the stack is empty) means that the stack has a state.

在这种情况下，如果push没有被调用(或者从逻辑上讲，栈为空)的情况下确保pop抛出一个异常，则意味着栈有一个状态。

youdao