Expressing yourself demo app

Let's try using some declarations, assignments, and operators. When we bundle these elements together into some meaningful syntax, we call it an expression. So let's write a quick app to try some out. We will then use Toast and Log to check our results.

Create a new project called Expressing Yourself, use a Blank Activity, and leave all the other settings at their defaults. The completed code that we will write in this project can be found in the Chapter 7/Expressing Yourself folder of the download bundle.

Switch to the MainActivity tab in the editor and we will write some code. In the onCreate method, just before the closing curly brace }, add this code:

int numMessages;

Directly below the previous line of code we will assign a value to numMessages. But as you begin to type nu notice we get a little pop-up message like this:

If you look at the first option in the pop-up message it is in fact numMessages. Android Studio is offering to complete our typing for us. We...