如何知道我是在 Java 中使用外部库还是内部库？

Question

So, I have to write this code and it must use only internal Java libraries.

I have to read the HTML content of a URL page and I have managed to do so, but I'm not sure if I have only used internal libraries because I'm not so familiar with Java, can some explain to me please?

I read that if it starts with "Java" it means that is a internal library, but Im not sure.

Below there is a image of what I have used. Thank you.

First pic: used in the main class Second pic: used in the reader class

Answer 1

If you are not pulling any external dependancies, as external jar's, maven or gradle dependancies, just using what ever JDK provides, then you are using internal Java libraries.

In both of your images imports are from JDK (internal Java libraries).

For other import if it starts with java or javax most likely it is internal library as well.