Learner

You have seen the access control modifier public used extensively in our Java examples. The access control modifier is applied to classes and class members (variables and methods) and determines what access code in other classes have to the class members.

In our first unit on objects we learned how objects can encapsulate fields and methods creating a custom data type we can use to model the actual objects in the problem we are trying to solve. These objects make it easy to describe and work with our data and facilitate reuse of code. In this unit we are going to explore some of the more powerful features of Java's object oriented design.

The FTC SDK Library is a library of classes that allow your programs to access and control all aspects of the Tetrix robot control system and the hardware devices attached to it. This library is the API for the control system and robot hardware. The library is included in the FTC SDK. You can access the library with the following import statement in an OpMode class:

The regular OpMode type that you would write extends the OpMode class in the FTC SDK. To add functionality, your code will override one or more of the following methods that exist in the base OpMode class:

• init()
• init_loop()
• start()
• stop()
• loop()

These methods are called at the appropriate time in response to button presses on the driver station (DS).

The term OpMode or Operational Mode (also Op Mode and opmode) refers to a class located within the FTC SDK (robot controller app source code). You create this class to add your code to the controller app. Your code is really just a part of the controller app, with the rest of the app supplied by the FTC source code. We don't modify that other part of the code, we just create the custom robot behavior we want by adding our own OpModes. Here is a quick video overview of OpModes.