Article: Tell Don't Ask: Raised Bed

RaisedBed.java

public class RaisedBed {
    private final RaisedBedId id;
    private final List<Plant> plants;

    public RaisedBed(RaisedBedId id, List<Plant> plants) {
        this.id = id;
        this.plants = plants;
    }

    public WateringResult waterWith(WaterValve waterValve) {
        for (Plant plant : plants) {
            WateringResult result = plant.waterWith(waterValve);
            if (!(result instanceof WateringResult.SuccessfullyWatered)) {
                return result;
            }
        }
        return WateringResult.success();
    }

    // truncated other methods
}