Java Fundamentals — Space Academy 3.0

You do not need all of Java to write great robot code. You need classes, fields, methods, control flow, and a working mental model of references.

Classes and objectsLink to this section

A subsystem is a class. Its fields hold hardware references and state; its methods expose intent to the rest of the robot.

java

public class Intake {
    private final DcMotor motor;
    private static final double COLLECT_POWER = 0.85;

    public Intake(HardwareMap hardwareMap) {
        motor = hardwareMap.get(DcMotor.class, "intake");
        motor.setZeroPowerBehavior(DcMotor.ZeroPowerBehavior.BRAKE);
    }

    public void collect() { motor.setPower(COLLECT_POWER); }
    public void eject()   { motor.setPower(-COLLECT_POWER); }
    public void stop()    { motor.setPower(0); }
}

Types you will use constantlyLink to this section

Type	Use	Note
double	Motor power, angles, distances	Default for all math
int	Encoder ticks, counters	Ticks are integers, never floats
boolean	Sensor states, toggles	Debounce gamepad reads
enum	Robot states	Far safer than magic ints

Enums for state machinesLink to this section

java

private enum LiftState { IDLE, RAISING, HOLDING, LOWERING }
private LiftState state = LiftState.IDLE;