Java is everywhere

The core Java fundamentals that we are about to learn apply to classes that we inherit from (such as Activity), as well as classes that we write ourselves (as we will start to do in Chapter 9, Object-Oriented Programming). As it is more logical to learn the basics before we write our own classes, we will be using the extended Activity class in a whole bunch of mini-projects in this chapter to learn and practice Java, and we will use Log and Toast again to observe the results of our coding. In addition, we will use more methods that we will write ourselves (called from buttons), as well as the overridden methods of the Activity class to trigger the execution of our code.

However, when we move onto Chapter 9, Object-Oriented Programming and start to write our own classes, as well as understand more about how classes written by others work, everything we have learned here will apply then too. In fact, all the Java that you learn in this chapter will work in the following Java...