Rather than asking the input system about the state of a certain peripheral in every single frame, we can let the input system know that we are interested in certain user-generated events and we can get notified whenever they occur. This is known as event listening, and it is better known in the design patterns world as Observer.
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It is important to know the most common design patters and when to apply them. To learn more about this topic, we recommend that you take a look at the book Design Patterns: Elements of Reusable Object-Oriented Software, Erich Gamma, Addison-Wesley Professional, or the freely available Game Programming Patterns, Robert Nystrom, Apress (http://gameprogrammingpatterns.com).
In this recipe, we will tell Libgdx to notify our sample application of the input events and show them all as a list on the screen. Examples of input events are mouse movements, touch dragging, scrolling, touching/clicking, key presses and releases, and...