Summary

This lesson uses file reading and writing as a vehicle to illustrate important data validation concepts when mapping text data to objects and receiving user input. It demonstrates many of the essential elements present in business applications, that is: ingesting data from an external source, enabling users to modify that data, and saving the data back to permanent storage.

Robust and well-designed apps, especially concerning the user interface, need to validate input in terms of data format and applicability and provide feedback when entered data is not appropriate. We round off the lesson by implementing the data access layer design pattern that will enable the code to be easily adapted to other data sources.

Learning Objectives

• Read planet data from a text file into a list of planet objects within a solar system object
• Create a basic command-line user interface with data validation and feedback that writes updated planet data back to file
• Take the file reading and writing functionality and split it out into a class that returns planet objects so you can easily change data sources in the future

Intended Audience

This lesson is ideal for anyone who already has some basic knowledge of C# and is looking to expand on that by learning about lists and files within the programming language.

Prerequisites

The ideal prerequisite for this lesson is our C# Loops Deep Dive lesson, but if you know what the .NET List class is and how to create one, then you’ll be able to follow along with these lectures and demonstrations. 

Resources

Demo source code: https://github.com/cloudacademy/csharp-lists-and-files