Java Only Benefits

Java has some unique features in it’s language base and one of those features is Static Factory Methods. This allows a simplar way to declare command groups.

sequence()

The sequence() static method allows for a sequential command group.

parallel()

The parallel() static method allows for a parallel command group

race()

The race() static method allows for a parallel race group.

Example code

Java

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import edu.wpi.first.wpilibj2.command.SequentialCommandGroup;

public class Example extends SequentialCommandGroup
{
    public Example()
    {
        addCommands(
            race(new DriveForward(), new ElevatorUP()),
            parallel(new ShootObject(), new LineupGoal()),
            sequence(new DriveReverse(), new StrafeRight()));
    }
}

If we analyze this command group we can break down what is happening.

  1. We have race(new DriveForward(), new ElevatorUP()) this will create a ParallelRaceGroup that has the two commands DriveForward() and ElevatorUP() run at the same time in a race. When one finishes it will stop the other.

  2. As the main command group is the SequentialCommandGroup we then move on to the next command which is a ParallelCommandGroup.

  3. The ParallelCommandGroup of parallel(new ShootObject(), new LineupGoal()) tells us that ShootObject() and LineupGoal() happen at the same time. When both are complete it will pass to the next command group.

  4. The last command group here is the sequence(new DriveReverse(), new StrafeRight()) which is also a SequentialCommandGroup. This group is telling the robot to DriveReverse() and when that is done to StrafeRight().