I read the guideline and requirement for the assignment. However, I am not sure about separating classes into different java files. I notice that we need to have several classes according to the assignment's guideline. In this case, do I split classes into different java files to submit even if it is on the same assignment?

Thanks,

Cheuk Kit Yu 

So for this assignment you are to choose two objects from real life that you would like to model using Object Oriented Programming.  For example I might pick a Cat and a Tree. So in the end, you would turn in 3 .java files, Cat.java Tree.java and Tester.java which would demonstrate that your other two classes are working. 

Take a look at the examples from the book and on the course GitHub for some inspiration