Creating a custom component

As we have seen in previous recipes, the Android SDK provides a wide range of components. But what happens when you can't find a prebuilt component that fits your unique needs? You can always create your own!

In this recipe, we will walk through creating a custom component that derives from the View class, just like the built-in widgets. Here's a high-level overview:

1. Create a new class that extends View.
2. Create custom constructor(s).
3. Override onMeasure(), as the default implementation returns a size of 100 x 100.
4. Override onDraw(), as the default implementation draws nothing.
5. Define custom methods and listeners (such as the onClick() event).
6. Implement custom functionality.

Note

Overriding onMeasure() and onDraw() is not strictly required, but the default behavior is likely not what you would want.

Getting ready

Start a new project in Android Studio and call it CustomView. Use the default wizard options, including the Phone & Tablet SDK and select Empty Activity when...