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File I/O

File I/O is a tricky topic for beginners. There are several built-in classes for reading and writing to files, so which one is best?

Well, it's not so easy. They all have their own purposes. Let's first learn some fundamental File I/O knowledge, then we'll look at examples of File I/O in Java in the next lesson.

Introduction​

File I/O, or file input/output, is the process of reading from or writing to a file on a computer's disk or other storage device. This is a fundamental operation in computer programming and is used in many applications to store and retrieve data.

When working with File I/O, it is important to understand the different modes of access that are available. These modes include reading, writing, and appending to a file. In addition, it is important to understand the different file formats and the tools that are available for working with these files.

File Formats​

There are many file formats that are used for storing data. Some of the most common file formats include text files, binary files, XML files, and JSON files.

Text files are simple files that contain plain text. They can be opened and edited with any text editor, and are often used for storing data that is meant to be read by humans.

Binary files are more complex than text files, and are used for storing data in a format that is optimized for processing by a computer. Binary files are typically used for storing data that is not meant to be read by humans, such as executable files or images. For example, .jpg or .png files are binary files. You cannot open them in a text editor and make sense of their contents. Rather, they need to be opened by a program that understands how to decode the binary data.

XML files are used for storing data in a structured format. They are often used for storing data that needs to be exchanged between different applications, and can represent complex data structures.

JSON is the modern version of XML, and is much more popular today. JavaScript Object Notation (JSON) files store data in key-value pairs, similar to what object syntax looks like in Javascript. We won't be covering JSON syntax in this series. Just know that it's a common way to store and send data.

Modes of Access​

When working with File I/O, it is important to understand the different modes of access that are available. These modes include reading, writing, and appending to a file.

Reading from a file involves opening the file and reading its contents. This can be useful for retrieving data that has been previously stored in a file.

Writing to a file involves opening the file and writing new data to it. This can be useful for storing data that has been generated by a program, or for creating new files.

Appending to a file involves opening the file and adding new data to the end of the file. This can be useful for adding new data to an existing file, without overwriting any existing data.

Summary​

File I/O is a fundamental operation in computer programming, and is used in many applications to store and retrieve data. When working with File I/O, it is important to understand the different modes of access that are available, as well as the different file formats and tools that are available for working with these files. With a solid understanding of File I/O theory, programmers can effectively work with files and use them to store and retrieve data in their applications.

Common Questions​

Why should I store data in files, instead of databases?​

While databases are an excellent way to store and manage data, learning File I/O still has its benefits. Here are a few reasons why learning File I/O is still important:

  1. Flexibility: File I/O provides a flexible and lightweight way of storing data, and can be used in situations where a database might not be feasible. For example, if you are working on a small project with limited resources, a database might be too complex and resource-intensive. In this case, File I/O can be a more practical solution.
  2. Portability: Files can be easily moved and shared between different systems and platforms, making them a portable solution for data storage. Databases, on the other hand, can be more difficult to move and share between systems.
  3. Legacy code: Many legacy systems and applications still use File I/O for data storage, and understanding how to work with files can be important for maintaining and updating these systems.
  4. Performance: In some cases, File I/O can be faster than database operations, especially for small datasets. If performance is a critical factor for your application, File I/O might be a better choice than a database. For example, storing settings in an application locally. Local settings for an application can be easily stored and read using a text file, JSON file, or similar type of file.
  5. Learning: Learning File I/O can help you better understand how data is stored and managed, which can be helpful when working with databases and other data storage systems. It can also help you better understand the tradeoffs between different data storage solutions.
  6. Interview Questions: File I/O questions are very common in interviews, so you should safely prepare your knowledge on the topic. In an interview for a Java job, this might entail describing different built-in classes that are used in File I/O, and their intended uses. File I/O is considered core knowledge of any programming language, and it's very worthwhile to learn.

In summary, while databases are an excellent way to store and manage data, learning File I/O is still important for many reasons. It can provide flexibility, portability, and performance advantages, and can be helpful for maintaining and updating legacy systems. Understanding File I/O can help you better understand how data is stored and managed, which can be helpful in many different contexts. Lastly, File I/O is an important topic when learning any programming language, and you should at least understand how to work with basic files, like text files.