Java Dev Exercises

Table of contents

• Exercise 1 - Abstraction
• Exercise 2 - Geolocation
• Exercise 3 - Stripe API invoices

Exercise 1 - Abstraction

OOP - Coniferous and Deciduous trees abstraction

Table of contents

• General info
• Abstraction

Ex 1 General info

Simple Java application implementing abstraction based on trees.

Abstraction

Main abstract class is Tree.
Tree has two subclasses - ConiferousTree and DeciduousTree.
For exercise implementation purposes there were created two classes:

• ConiferousTree - PineTree and SpruceTree
• DeciduousTree - AppleTree and ChestnutTree

And also a Main class which includes main() method to present differences between mentioned implemented classes and subclasses.

Exercise 2 - Geolocation

Spring Boot application for geolocating devices

Table of contents

• General info
• Device
• Location

Ex-2-General info

Application uses local MySQL database to store devices and locations data.

Device

Devices consist of id and name.

DeviceController has four endpoints for api/device:

• get all devices GET
• get device by ID GET /{deviceId}
• create device POST
• delete device DELETE /{deviceId}

Location

Location consists of id, deviceId, longitude, latitute and date. For application purposes latitute and longitude is generated randomly everytime methods for getting or saving current location are called. Each device has its own Location history. Every Location saved in database has a date, when it was saved, and a flag if it's the last checked device location. Each time we save new current location it becomes a new last checked location, and flag of previous one is set to false.

LocationControllerr has four endpoints for api/location:

• get current device location GET /{deviceId}/current
• get last device location GET /{deviceId}/last
• get device locations history GET /{deviceId}/history
• save current device location POST /{deviceId}

Exercise 3 - Stripe API invoices

Application using Stripe API for creating and retrieving invoices

Table of contents

• General info
• Authentication
• Stripe API
• Invoices

Ex 3 General info

Application uses Stripe API and local MySQL database.

Authentication

Application uses Spring Boot Security. Authentication is done as basic authentication, using email (username) and a password. Every created user is saved to local MySQL database and also created as Customer in Stripe API.

RegistrationController class provides /register endpoint to register user and create customer. While registering, application checks if email is taken/invalid.

After successfully creating user, every resource can be accessed by providing login credentials

Stripe API

Application provide endpoints /api/invoice to:

• create invoice POST
• retrieve all customer's invoices GET /list
• retrieve invoice by ID GET /{invoiceId}

InvoiceController has all mentioned endpoints in itself.

Invoices

For creating invoices, application needs a List of CreateInvoiceDTO objects. Every CreateInvoiceDTO object is used to create Product object which consists of a name given by user in CreateInvoiceDTO.productName field.

Product object is used to create Price object. Price consists of Product.id, Long UnitAmount and String currency fields.

Finally, Price object is used to create InvoiceItem objects, which are added automatically, when Invoice is created.