File I/O - Absolute Java - page 581

already exists, the old contents of stuff.txt will be lost. If the file stuff.txt does not
exist, then a new, empty file named stuff.txt will be created.
We want to associate the output stream outputStream with the file named stuff.txt .
However, the class PrintWriter has no constructor that takes a file name as its argument.
So we use the class FileOutputStream to create a stream that can be used as an argument
to a PrintWriter constructor. The expression

FileOutput
Stream

new FileOutputStream("stuff.txt")
takes a file name as an argument and creates an anonymous object of the class
FileOutputStream , which is then used as an argument to a constructor for the class
PrintWriter as follows:

new PrintWriter( new FileOutputStream("stuff.txt"))
This produces an object of the class PrintWriter that is connected to the file
stuff.txt . Note that the name of the file, in this case, stuff.txt , is given as a
String value and so is given in quotes.
If you want to read the file name from the keyboard, you could read the name
to a variable of type String and use the String variable as the argument to the
FileOutputStream constructor.
When you open a text file in the way just discussed, a FileNotFoundException
can be thrown, and any such possible exception should be caught in a catch
block. (Actually, it is the FileOutputStream constructor that might throw the
FileNotFoundException , but the net effect is the same.)
Notice that the try block in Display 10.1 encloses only the opening of the file.
That is the only place that an exception might be thrown. Also note that the variable
outputStream is declared outside of the try block—this is so that this variable can be
used outside of the try block. Remember, anything declared in a block (even in a try
block) is local to the block.

file name

reading the
file name

FileNot
Found
Exception

Display 10.1 Sending Output to a Text File (part 1 of 2)

1 import java.io.PrintWriter;
2 import java.io.FileOutputStream;
3 import java.io.FileNotFoundException;

4 public class TextFileOutputDemo
5 {
6 public static void main(String[] args)
7 {
8 PrintWriter outputStream = null ;
9 try
10 {
11 outputStream =
12

new PrintWriter( new FileOutputStream("stuff.txt"));

13 }
14 catch (FileNotFoundException e)

(continued)