Introduction to FRC Programming

What is Java?

  • Released by Sun Microsystems in 1995
  • High-Level, Class-Based, Object Oriented programming language
  • Code runs in a Virtual Machine
    • Java is compiled to ByteCode
    • Virtual machine converts ByteCode at runtime
  • Syntax is based off of C/C++
  • Strongly and Statically Typed

Why do we use Java?

  • Managed Language
    • Memory usage is tracked by Virtual Machine
    • Memory that is no longer used is freed by the Garbage Collector
    • Eliminates some common, and hard to debug, issues that can arise in code
  • Very Well Supported Language
    • Java is one of the most commonly used languages in the world
    • Java is the most commonly used language in FRC
    • Java is commonly taught in schools (including Birmingham)

Prerequisites

Here are links for the standard tool set for FRC programming

WPILib Installer

FRC Game Tools (Optional)

The WPILib Installer will install a number of utilities onto your computer including a specially configured instance of VSCode. This version of VSCode should be used, even if you have another instance installed, since it is configured to correctly build and deploy projects to FRC robots.

The FRC Game Tools are not required to program a robot, but are required if you want to control the robot from your programming computer.

Variables

Variables store information for your program including:

  • Numbers
  • Text
  • References to hardware

Variable Examples

// CAN IDs
public int lfDriveMotorID = 1;
public int lrDriveMotorID = 2;
public int rfDriveMotorID = 3;
public int rrDriveMotorID = 4;
 
// Drivetrain Constants
public Distance wheelDiameter = Inches.of(3);
public double driveRatio = 1.0/8.45;

Variable - Primitives

Type Description
Boolean bool true or false, 0 or 1
Integers byte Whole number from -128 to 127
short Whole number from -32,768 to 32,767
int Whole number from -2,147,483,648 to 2,147,483,647
long Whole number -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
Floating Point float Fractional Number Significant to 6 to 7 decimal places
double Fractional Number Significant to 15 decimal places
Character char Stores a single character/letter or ASCII values

Variable - Object

  • An object is a collection of variables and methods.
  • Used to logically group things together in programs.
    • Example: The Drivetrain object includes all the drive motors
  • Fundamental part of java

All variables in Java, except for primitive types, are an object.