Java™ How To Program (Early Objects), Tenth Edition

15.1 Introduction

Data stored in variables and arrays is temporary—it’s lost when a local variable goes out of scope or when the program terminates. For long-term retention of data, even after the programs that create the data terminate, computers use files. You use files every day for tasks such as writing a document or creating a spreadsheet. Computers store files on secondary storage devices, including hard disks, flash drives, DVDs and more. Data maintained in files is persistent data—it exists beyond the duration of program execution. In this chapter, we explain how Java programs create, update and process files.

We begin with a discussion of Java’s architecture for handling files programmatically. Next we explain that data can be stored ...