Java IO Tutorial

Java Io 

1	Java IO Tutorial
2	Java IO Overview
3	Java IO: Files
4	Java IO: Pipes
5	Java IO: Networking
6	Java IO: Byte & Char Arrays
7	Java IO: System.in, System.out, and System.error
8	Java IO: Streams
9	Java IO: Input Parsing
10	Java IO: Readers and Writers
11	Java IO: Concurrent IO
12	Java IO: Exception Handling
13	Java IO: InputStream
14	Java IO: OutputStream
15	Java IO: FileInputStream
16	Java IO: FileOutputStream
17	Java IO: RandomAccessFile
18	Java IO: File
19	Java IO: PipedInputStream
20	Java IO: PipedOutputStream
21	Java IO: ByteArrayInputStream
22	Java IO: ByteArrayOutputStream
23	Java IO: FilterInputStream
24	Java IO: FilterOutputStream
25	Java IO: BufferedInputStream
26	Java IO: BufferedOutputStream
27	Java IO: PushbackInputStream
28	Java IO: SequenceInputStream
29	Java IO: DataInputStream
30	Java IO: DataOutputStream
31	Java IO: PrintStream
32	Java IO: ObjectInputStream
33	Java IO: ObjectOutputStream
34	Java IO: Serializable
35	Java IO: Reader
36	Java IO: Writer
37	Java IO: InputStreamReader
38	Java IO: OutputStreamWriter
39	Java IO: FileReader
40	Java IO: FileWriter
41	Java IO: PipedReader
42	Java IO: PipedWriter
43	Java IO: CharArrayReader
44	Java IO: CharArrayWriter
45	Java IO: BufferedReader
46	Java IO: BufferedWriter
47	Java IO: FilterReader
48	Java IO: FilterWriter
49	Java IO: PushbackReader
50	Java IO: LineNumberReader
51	Java IO: StreamTokenizer
52	Java IO: PrintWriter
53	Java IO: StringReader
54	Java IO: StringWriter

Java IO Tutorial

 
By Jakob Jenkov

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Java IO is an API that comes with Java which is targeted at reading and writing data (input and output). Most applications need to process some input and produce some output based on that input. For instance, read data from a file or over network, and write to a file or write a response back over the network.

The Java IO API is located in the Java IO package (java.io). If you look at the Java IO classes in the java.iopackage the vast amount of choices can be rather confusing. What is the purpose of all these classes? Which one should you choose for a given task? How do you create your own classes to plugin? etc. The purpose of this tutorial is to try to give you an overview of how all these classes are grouped, and the purpose behind them, so you don't have to wonder whether you chose the right class, or whether a class already exists for your purpose.

The Scope of the Java IO (java.io) Package

The java.io package doesn't actually address all types of input and output. For instance, input from and output to a GUI or web page is not covered in the Java IO package. Those types of input are covered elsewhere, for instance by the JFC classes in the Swing project, or the Servlet and HTTP packages in the Java Enterprise Edition.

The Java IO package is primarily focused on input and output to files, network streams, internal memory buffers etc. However, the Java IO package does not contain classes to open network sockets which are necessary for network communication. For that purpose you need to use the Java Networking API. Once you have opened a socket (network connection) though, you read and write data to and from it via Java IO's InputStream and OutputStream classes.

Java NIO - The Alternative IO API

Java also contains another IO API called Java NIO. It contains classes that does much of the same as the Java IO and Java Networking APIs, but Java NIO can work in non-blocking mode. Non-blocking IO can in some situations give a big performance boost over blocking IO.

More Java IO Tools, Tips etc.

The tutorial trail called Java How To's and Utilities also contain a few Java IO utilities - e.g. replacing strings in streams, iterating streams using buffers etc.

The Scope of this Java IO Tutorial

The tutorial starts by giving you a solid overview of how the Java IO APIs work, and how you are supposed to use them. After that the tutorial switches to covering the core classes in the Java IO API.

The coverage of the classes in this tutorial is not just an API listing. It's more than just a class listing (you can get that from Sun's official Java Doc's). Rather each text is a short introduction to the class, its purpose, and a few examples of how to use it. In other words, some of the stuff you don't find in Sun's official Java Doc's.

Java 5 to Java 8

The first version of this Java IO tutorial was written based on Java 5, but the classes work pretty much the same all the way up to Java 8 which is the latest version of Java at the time of writing.

Next:   Java IO Overview