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Lesson 3.3: Using boolean Values for On-or-Off Robot State

Technical Context​

Sensors like Touch Sensors or Limit Switches only have two states: pressed or not pressed. Using boolean flags to store these states allows the robot to make binary decisions, such as stopping a lift before it hits a physical hard-stop and causes mechanical failure.

How boolean Values Simplify Robot Decisions​

A boolean is a primitive datatype that can only hold one of two values: true or false. In the FTC environment, digital sensors and gamepad buttons are inherently boolean. When you call getState() on a DigitalChannel (like a touch sensor), the SDK returns a boolean. Storing this result in a variable allows you to "capture" the state at a specific moment in the loop() cycle and use it for logic comparisons.

Annotated Code​

@TeleOp(name="Boolean_Logic")
public class BooleanLogic extends OpMode {

    // Declaring a boolean to track if the safety limit is reached
    boolean isAtLimit;
    DcMotor lift;
    DigitalChannel touch;

    @Override
    public void init() {
        lift  = hardwareMap.get(DcMotor.class, "lift");
        touch = hardwareMap.get(DigitalChannel.class, "limit_switch");
    }

    @Override
    public void loop() {
        // Capturing the current hardware state into the boolean variable
        isAtLimit = touch.getState();
        telemetry.addData("Safe to move?", isAtLimit);
    }
}

Fill-in-the-Blank Practice​

  1. A variable type that can only represent two possible states is a/an __________.
  2. The default value of a boolean variable in Java, if not assigned, is __________.
  3. To invert a boolean value (changing true to false), we use the __________ operator.
Show answers
  1. boolean
  2. false
  3. ! (the logical NOT operator)

Template Challenge​

Robot Scenario: Capture the state of the "A" button on gamepad1 into a boolean variable and send that variable to the Driver Station via telemetry.

Unit 3 simulator
Tracks `String`, `double`, `boolean`, and `int` variables as you edit.
Supports telemetry, `gamepad1`, simple `if` blocks, and basic `setPower()` math.
Does not simulate full hardware behavior or complex Java control flow.
Show answer
@Override
public void loop() {
    boolean buttonState = gamepad1.a;
    telemetry.addData("Button A Pressed", buttonState);
}

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