File I/O - Absolute Java - page 580

Text Files versus Binary Files
Files that you write and read using an editor are called text files . Binary files represent data
in a way that is not convenient to read with a text editor, but that can be written to and read
from a program very efficiently.

Self-Test Exercises

1. A stream is a flow of data. From where and to where does the data flow in an
input stream? From where and to where does the data flow in an output stream?

2. What is the difference between a binary file and a text file?

10.2 Text Files

Polonius: What do you read, my lord?
Hamlet: Words, words, words.

WILLIAM SHAKESPEARE, Hamlet

In this section, we describe the most common ways to do text file I/O in Java.

Writing to a Text File
The class PrintWriter is the preferred stream class for writing to a text file. An object
of the class PrintWriter has the methods print and println , which are like the
methods System.out.print and System.out.println that you can use for screen
output. However, with an object of the class PrintWriter , the output goes to a text
file. Display 10.1 contains a simple program that uses PrintWriter to send output to
a text file. Let's look at the details of that program.
All the file I/O-related classes we introduce in this chapter are in the package java.io ,
so all our program files begin with import statements similar to the ones in Display 10.1.
The program in Display 10.1 creates a text file named stuff.txt that a person can
read using an editor, or that another Java program can read. The program creates an
object of the class PrintWriter as follows:

PrintWriter

java.io

outputStream =
new PrintWriter( new FileOutputStream("stuff.txt"));
The variable outputStream is of type PrintWriter and is declared outside the try
block. The preceding two lines of code connect the stream named outputStream to
the file named stuff.txt . This is called opening the file . When you connect a file to a
stream in this way, your program always starts with an empty file. If the file stuff.txt

opening a file