Package edu.wpi.first.wpilibj2.command.button

Class Trigger

java.lang.Object
edu.wpi.first.wpilibj2.command.button.Trigger
All Implemented Interfaces:
BooleanSupplier
Direct Known Subclasses:
Button
public class Trigger
extends Object
implements BooleanSupplier
This class provides an easy way to link commands to conditions.

It is very easy to link a button to a command. For instance, you could link the trigger button of a joystick to a "score" command.

Triggers can easily be composed for advanced functionality using the and(BooleanSupplier), or(BooleanSupplier), negate() operators.

This class is provided by the NewCommands VendorDep

  • Constructor Details

    • Trigger

      public Trigger​(EventLoop loop, BooleanSupplier condition)
      Creates a new trigger based on the given condition.
      Parameters:
      loop - The loop instance that polls this trigger.
      condition - the condition represented by this trigger

    • Trigger

      public Trigger​(BooleanSupplier condition)
      Creates a new trigger based on the given condition.

      Polled by the default scheduler button loop.

      Parameters:
      condition - the condition represented by this trigger

    • Trigger

      @Deprecated public Trigger()
      Deprecated.
      Creates a new trigger that is always `false`.

  • Method Details

    • onTrue

      public Trigger onTrue​(Command command)
      Starts the given command whenever the condition changes from `false` to `true`.
      Parameters:
      command - the command to start
      Returns:
      this trigger, so calls can be chained

    • onFalse

      public Trigger onFalse​(Command command)
      Starts the given command whenever the condition changes from `true` to `false`.
      Parameters:
      command - the command to start
      Returns:
      this trigger, so calls can be chained

    • whileTrue

      public Trigger whileTrue​(Command command)
      Starts the given command when the condition changes to `true` and cancels it when the condition changes to `false`.

      Doesn't re-start the command if it ends while the condition is still `true`. If the command should restart, see RepeatCommand.

      Parameters:
      command - the command to start
      Returns:
      this trigger, so calls can be chained

    • whileFalse

      public Trigger whileFalse​(Command command)
      Starts the given command when the condition changes to `false` and cancels it when the condition changes to `true`.

      Doesn't re-start the command if it ends while the condition is still `false`. If the command should restart, see RepeatCommand.

      Parameters:
      command - the command to start
      Returns:
      this trigger, so calls can be chained

    • toggleOnTrue

      public Trigger toggleOnTrue​(Command command)
      Toggles a command when the condition changes from `false` to `true`.
      Parameters:
      command - the command to toggle
      Returns:
      this trigger, so calls can be chained

    • toggleOnFalse

      public Trigger toggleOnFalse​(Command command)
      Toggles a command when the condition changes from `true` to the low state.
      Parameters:
      command - the command to toggle
      Returns:
      this trigger, so calls can be chained

    • whenActive

      @Deprecated public Trigger whenActive​(Command command)
      Deprecated.
      Use onTrue(Command) instead.
      Starts the given command whenever the trigger just becomes active.
      Parameters:
      command - the command to start
      Returns:
      this trigger, so calls can be chained

    • whenActive

      @Deprecated public Trigger whenActive​(Runnable toRun, Subsystem... requirements)
      Deprecated.
      Replace with onTrue(Command), creating the InstantCommand manually
      Runs the given runnable whenever the trigger just becomes active.
      Parameters:
      toRun - the runnable to run
      requirements - the required subsystems
      Returns:
      this trigger, so calls can be chained

    • whileActiveContinuous

      @Deprecated public Trigger whileActiveContinuous​(Command command)
      Deprecated.
      Use whileTrue(Command) with RepeatCommand, or bind command::schedule to BooleanEvent.ifHigh(Runnable) (passing no requirements).
      Constantly starts the given command while the button is held.

      Command.schedule() will be called repeatedly while the trigger is active, and will be canceled when the trigger becomes inactive.

      Parameters:
      command - the command to start
      Returns:
      this trigger, so calls can be chained

    • whileActiveContinuous

      @Deprecated public Trigger whileActiveContinuous​(Runnable toRun, Subsystem... requirements)
      Deprecated.
      Use whileTrue(Command) and construct a RunCommand manually
      Constantly runs the given runnable while the button is held.
      Parameters:
      toRun - the runnable to run
      requirements - the required subsystems
      Returns:
      this trigger, so calls can be chained

    • whileActiveOnce

      @Deprecated public Trigger whileActiveOnce​(Command command)
      Deprecated.
      Use whileTrue(Command) instead.
      Starts the given command when the trigger initially becomes active, and ends it when it becomes inactive, but does not re-start it in-between.
      Parameters:
      command - the command to start
      Returns:
      this trigger, so calls can be chained

    • whenInactive

      @Deprecated public Trigger whenInactive​(Command command)
      Deprecated.
      Use onFalse(Command) instead.
      Starts the command when the trigger becomes inactive.
      Parameters:
      command - the command to start
      Returns:
      this trigger, so calls can be chained

    • whenInactive

      @Deprecated public Trigger whenInactive​(Runnable toRun, Subsystem... requirements)
      Deprecated.
      Construct the InstantCommand manually and replace with onFalse(Command)
      Runs the given runnable when the trigger becomes inactive.
      Parameters:
      toRun - the runnable to run
      requirements - the required subsystems
      Returns:
      this trigger, so calls can be chained

    • toggleWhenActive

      @Deprecated public Trigger toggleWhenActive​(Command command)
      Deprecated.
      Use toggleOnTrue(Command) instead.
      Toggles a command when the trigger becomes active.
      Parameters:
      command - the command to toggle
      Returns:
      this trigger, so calls can be chained

    • cancelWhenActive

      @Deprecated public Trigger cancelWhenActive​(Command command)
      Deprecated.
      Instead, pass this as an end condition to Command.until(BooleanSupplier).
      Cancels a command when the trigger becomes active.
      Parameters:
      command - the command to cancel
      Returns:
      this trigger, so calls can be chained

    • getAsBoolean

      public boolean getAsBoolean()
      Specified by:
      getAsBoolean in interface BooleanSupplier

    • and

      public Trigger and​(BooleanSupplier trigger)
      Composes two triggers with logical AND.
      Parameters:
      trigger - the condition to compose with
      Returns:
      A trigger which is active when both component triggers are active.

    • or

      public Trigger or​(BooleanSupplier trigger)
      Composes two triggers with logical OR.
      Parameters:
      trigger - the condition to compose with
      Returns:
      A trigger which is active when either component trigger is active.

    • negate

      public Trigger negate()
      Creates a new trigger that is active when this trigger is inactive, i.e. that acts as the negation of this trigger.
      Returns:
      the negated trigger

    • debounce

      public Trigger debounce​(double seconds)
      Creates a new debounced trigger from this trigger - it will become active when this trigger has been active for longer than the specified period.
      Parameters:
      seconds - The debounce period.
      Returns:
      The debounced trigger (rising edges debounced only)

    • debounce

      public Trigger debounce​(double seconds, Debouncer.DebounceType type)
      Creates a new debounced trigger from this trigger - it will become active when this trigger has been active for longer than the specified period.
      Parameters:
      seconds - The debounce period.
      type - The debounce type.
      Returns:
      The debounced trigger.