Extra Data Types

Beyond the basic data types (int, double, boolean, String), Java has specialized types for specific situations.

Enums

An enum represents a fixed set of named constants:

public enum ClawState {
    OPEN,
    CLOSED,
    CLOSED_PARTIAL,
    INTAKE_CLOSE
}

Using Enums

public class Claw {
    public enum State {
        CLOSED, OPEN, CLOSED_PARTIAL, INTAKE_CLOSE, CLOSED_WALL
    }
    
    public static State state;
    
    public void setState(State newState) {
        state = newState;
        switch(state) {
            case OPEN:
                claw.setPosition(OUTTAKE_CLAW_OPEN);
                break;
            case CLOSED:
                claw.setPosition(OUTTAKE_CLAW_CLOSED);
                break;
            case CLOSED_PARTIAL:
                claw.setPosition(OUTTAKE_CLAW_CLOSED_PARTIAL);
                break;
        }
    }
}

// Usage
robotClaw.setState(Claw.State.OPEN);

Arrays

Arrays store multiple values of the same type:

// Declaration and initialization
double[] motorPowers = new double[4];
String[] teamNames = {"Team A", "Team B", "Team C"};

// Access by index (starts at 0)
motorPowers[0] = 0.5;
String firstTeam = teamNames[0];

// Get length
int arraySize = motorPowers.length;

ArrayLists

ArrayLists are resizable arrays that can grow and shrink:

import java.util.ArrayList;

ArrayList<String> teamMembers = new ArrayList<>();

// Add elements
teamMembers.add("Alice");
teamMembers.add("Bob");

// Access elements
String member = teamMembers.get(0);

// Remove elements
teamMembers.remove("Bob");

// Get size
int size = teamMembers.size();

Generic Types

ArrayLists use generic types to specify what they contain:

ArrayList<Integer> scores = new ArrayList<>();
ArrayList<Double> distances = new ArrayList<>();
ArrayList<Boolean> states = new ArrayList<>();

Quick Reference

Type	What It Stores	Example
enum	Fixed set of named constants	ClawState.OPEN
array[]	Fixed-size list of same type	int[] numbers = {1,2,3}
ArrayList	Resizable list of same type	ArrayList<String> names