The previous sections of this paper have described the contents of the first 20 lectures. This is a turning point in the course. Although there are a few important aspects of the Java language that are still to come, most of the important ones have now been introduced. The remaining lectures of the course are mainly concerned with introducing two important APIs: the Swing API and the Collections API.

Although both of these APIs came into being when Java 2 was released, they are both considered by Sun to be part of the Core APIs of Java.

One of the main aims of the second half of the course is to become familiar with these two APIs. They are both quite large: the course's aim is to introduce the basic ideas giving the students sufficient knowledge to look at the other parts of the API on their own.

Note the emphasis in this part of the course is on using the code of existing libraries: by taking a ride on the work of others, Java gives even the beginner the possibility of easily building reasonably powerful pieces of code.