Code:
isOpen = false;
buttonValue = mainStick.getTrigger();
if(buttonValue)
{
if(!isOpen)
{
gearDropper.set(true);
}
else
{
gearDropper.set(false);
}
isOpen = !isOpen;
}
isOpen will be always false, you have to put the variable global.
Check if your joystick is really in port 0 in driverStation.