Android 9 Development Cookbook - Third Edition

How to do it...

We will create a new class for our custom component to derive from the Android View class. Our custom component could be a subclass of an existing class, such as the activity, but we will create it in a separate file to make it easier to maintain. Here are the steps:

1. Start by creating a new Java class and calling it CustomView. This is where we will implement our custom component, as described in the Introduction.
2. Change the class constructor so it extends View. It should look as follows:

public class CustomView extends View {

3. Define a Paint object for the class, which will be used in onDraw():

final Paint mPaint = new Paint();

4. Create a default constructor, which requires the activity Context, so we can inflate the view. ...