Java in a Nutshell, 9th Edition

Chapter 11. File Handling and I/O

Java has had input/output (I/O) support since the very first version. However, due to Java’s strong desire for platform independence, the earlier versions of I/O emphasized portability over functionality. As a result, these systems have undergone multiple significant revisions over the platform’s history.

In this chapter we will introduce modern, recommended approaches to file I/O. After that, we’ll touch on the “classic” APIs that you still may encounter in some code. Finally, we’ll cover network communication.

Path

When working with files, you have to know the location of the file you want to access. The Path interface in the java.nio.file package can be thought of as representing this file location whether it exists or not. A path is:

• System dependent

• Hierarchical

• Composed of a sequence of path elements

• Hypothetical (may not exist yet or may have been deleted)

Path is an interface, which enables different filesystem providers to each implement system-specific features while retaining the overall abstraction. As opposed to the legacy File class we’ll see later, Path has no notion of the contents of a file and purely represents a file’s location within the filesystem (which itself may be abstracted or virtualized).

Note

What’s that NIO in the package name? As mentioned in the introduction, File I/O has seen several large revisions across Java’s history. NIO stands for “New I/O.” Java 7 in particular brought in a brand-new I/O API—usually ...