Working with Input and Output in Java

Several exceptions in the java.io package may occur when you are working with files and streams.

A FileNotFound exception occurs when you try to create a stream or file object using a file that couldn't be located.

An EOFException indicates that the end of a file has been reached unexpectedly as data was being read from the file through an input stream.

These exceptions are subclasses of IOException. One way to deal with all of them is to enclose all input and output statements in a try-catch block that catches IOException objects. Call the exception's toString() or getMessage() methods in the catch block to find out more about the problem.

All byte streams are either a subclass of InputStream or OutputStream. These classes are abstract, so you cannot create a stream by creating objects of these classes directly. Instead, you create streams through one of their subclasses, such as the following:

• FileInputStream and FileOutputStream—Byte streams stored in files on disk, CD-ROM, or other storage devices

• DataInputStream and DataOutputStream—A filtered byte stream from which data such as integers and floating-point numbers can be read

InputStream is the superclass of all input streams.

The byte streams you will work with most often are likely to be file streams, which are used to exchange data with files on your disk drives, CD-ROMs, or other storage devices you can refer to by using a folder path and filename.

You can send bytes to a file output stream and receive bytes from a file input stream.