Debouncing

There are many cases where a mechanical switch such as a button or a limit switch literally bounces when you change its position. The process of ignoring the bouncing so you don't repeatedly act on the switch unintentionally is called de-bouncing. There are several ways to do this; one is to start a timer when the switch change is detected and then ignore any subsequent switch changes until the timer expires. The code looks like this:

package frc.robot;

import edu.wpi.first.wpilibj.TimedRobot;

import edu.wpi.first.wpilibj.XboxController;

import edu.wpi.first.wpilibj.Timer;

public class Robot extends TimedRobot {

  XboxController xbox;

  Timer debounce;

  @Override

  public void robotInit() {

     xbox = new XboxController(0);

     debounce = new Timer();

     debounce.start();

  }

  @Override

  public void robotPeriodic() {

     if (xbox.getAButton()) {

         // A button pressed

         if (debounce.hasPeriodPassed(0.5)) {

             // more than half-second since last press

             System.out.println("A button pressed!");

             // restart debounce timer so we ignore presses in next half second

             debounce.reset();

         }

     }

  }

}

Try commenting out the if statement (and its closing brace) and see what happens when you press the A button