Operators Lesson

Making Your Data Work

Operators are the special symbols that perform operations on your variables and values. They are the verbs of programming, allowing you to do everything from basic math to complex logical comparisons.

Categories of Operators

In Java, operators are the building blocks for any computation or decision-making in your code. They can be grouped into several key categories, each with a specific purpose. Let's explore the most common ones you'll use in FRC.

Arithmetic Operators

These are the operators used for basic mathematical calculations. They work just like they do in algebra.

+ : Addition
- : Subtraction
* : Multiplication
/ : Division
% : Modulus (gives the remainder of a division)

// FRC Example: Calculating total points
int autoPoints = 15;
int teleopPoints = 30;
int totalScore = autoPoints + teleopPoints; // totalScore is 45

// FRC Example: Finding the remainder
int totalGamePieces = 10;
int piecesPerCycle = 3;
int piecesLeftOver = totalGamePieces % piecesPerCycle; // piecesLeftOver is 1

Integer Division

Be careful when dividing two integers. Java performs integer division, which truncates (chops off) any decimal part. For example, 10 / 3 will result in 3, not 3.333. To get a decimal result, at least one of the numbers must be a double: 10.0 / 3.

Assignment Operators

Assignment operators are used to assign values to variables. The basic assignment operator is =. Java also provides compound assignment operators that combine an arithmetic operation with assignment for more concise code.

= : Assign value (e.g., `x = 5;`)
+= : Add and assign (e.g., `x += 5;` is the same as `x = x + 5;`)
-= : Subtract and assign
*= : Multiply and assign
/= : Divide and assign

// FRC Example: Incrementing a score counter
int score = 0;
score += 5; // score is now 5
score += 10; // score is now 15

// FRC Example: Reducing motor power
double motorSpeed = 1.0;
motorSpeed -= 0.25; // motorSpeed is now 0.75

Comparison (Relational) Operators

These operators compare two values and return a boolean result (either true or false). They are the foundation of all `if` statements and conditional logic.

== : Equal to
!= : Not equal to
> : Greater than
< : Less than
>= : Greater than or equal to
<= : Less than or equal to

// FRC Example: Checking if an arm has reached its target
double targetAngle = 90.0;
double currentAngle = 90.1;
boolean atTarget = (currentAngle >= targetAngle); // atTarget is true

// FRC Example: Checking if we are on the red alliance
String alliance = "Red";
boolean isRed = (alliance == "Red"); // isRed is true

Logical Operators

Logical operators are used to combine multiple boolean expressions into a single result. They are essential for creating complex conditions in your code.

&& : Logical AND (returns `true` only if both expressions are true)
|| : Logical OR (returns `true` if at least one expression is true)
! : Logical NOT (inverts the boolean value; `true` becomes `false`)

// FRC Example: Checking if it's safe to shoot
boolean shooterAtSpeed = true;
boolean turretIsAimed = false;

// Using AND: both must be true
boolean readyToShoot = shooterAtSpeed && turretIsAimed; // readyToShoot is false

// Using OR: only one needs to be true
boolean isEnabled = true;
boolean inAuto = false;
boolean isRobotActive = isEnabled || inAuto; // isRobotActive is true

// Using NOT
boolean hasGamePiece = false;
boolean needsToRunIntake = !hasGamePiece; // needsToRunIntake is true

Test Your Knowledge

Question: You want to run the intake motor only if the robot is enabled AND the driver is pressing the 'A' button. Which logical operator would you use to combine these two conditions?