Fix your Delivery Drone Fleet

Amazon Fresh is adding a new service that offers fresh fruit delivery. A drone picks fruit fresh from the tree or vine and flies it straight from the orchard to the hungry customer who ordered it.

You are working on the system that manages the fleet of drones used for this service. Every drone in the fleet is assigned a registration number by a local jurisdiction. You are going to try to address three different issues your team is facing:

Issue 1 - Performance

As the fleet has expanded to tens of thousands of drones, there have been performance issues adding and removing drones from the fleet system.

Issue 2 - Duplicate Drones

There have been bugs related to duplicate drone information in the fleet.

Issue 3 - Checking for Drones from a specific location

You are also adding a feature that checks whether the fleet contains any drone from a particular location. This will help enable features that the legal team needs to deal with drone licensing audits from various cities and countries.

Getting familiar with DroneFleet and DeliveryDrone code

Let's start by reading through the DroneFleet and DeliveryDrone source code.

You'll note that the DeliveryDrone class includes a registrationNumber attribute representing the registration id for this drone. It also includes a locationCode which is a code identifying the jurisdiction where this drone is registered. Every combination of locationCode and registrationNumber are globally unique -- they identify a single drone.

The DroneFleet contains any number of DeliveryDrone objects. Later our team will be adding more business logic to this class, but right now it is basically a wrapper around a collection of DeliveryDrone objects, supporting simple operations such as addDrone().

Tackling performance and duplicate drones

Let's focus on the first two issues - performance and duplicate drones. Modify the DroneFleet and DeliveryDrone classes so that our drone fleet can't contain drones with the same registrationNumber from the same locationCode. The changes you make should also address the performance issue we are experiencing. We should be able to add and remove drones from the fleet in constant time. That means we'll be testing your implementation of addDrone and removeDrone. You shouldn't yet touch containsDroneFromLocation, but the rest of the code is free game!

Once you're ready to see if your addDrone and removeDrone methods are working as expected, run the tests in DroneFleetTest

HINT: I changed the type of drones but my remove and add tests are still failing.

HINT: I can't find DeliveryDrones implementation of equals to fix.

HINT: I made sure to define equivalency rules for DeliveryDrones but my remove and add tests are STILL failing.

Checking for Drones from a specific location

Now let's work on issue 3, implementing the new functionality! The method header has already been created for this functionality in DroneFleet. Read through the containsDroneFromLocation JavaDoc in DroneFleet and fill in the implementation for the method.

Once you're ready to see if your containsDroneFromLocation method os working as expected, run the tests in DroneFleetContainsTest

HINT:

• containsDroneFromLocation tests fail