Package: java.io
The java.io package provide support for system input and output through data streams, serialization and the file system. Make a note that if a null value is passes to the constructor of classes under java.io will throw a NullPointException.
Target Audience
This document is intended to served as a reference for Student and IT professionals seeking example usage of each classes and respective methods of java.io package.
Compatibility Version
Since JDK 1.0
java.io Package Classes
The following are the classes under the java.io package. Please master the majority of these classes as these are all helpful.
| Class | Description |
|---|---|
| BufferedInputStream | A BufferedInputStream adds functionality to another input stream-namely, the ability to buffer the input and to support the mark and reset methods. |
| BufferedOutputStream | The class implements a buffered output stream. |
| BufferedReader | Reads text from a character-input stream, buffering characters so as to provide for the efficient reading of characters, arrays, and lines. |
| BufferedWriter | Writes text to a character-output stream, buffering characters so as to provide for the efficient writing of single characters, arrays, and strings. |
| ByteArrayInputStream | A ByteArrayInputStream contains an internal buffer that contains bytes that may be read from the stream. |
| ByteArrayOutputStream | This class implements an output stream in which the data is written into a byte array. |
| CharArrayReader | This class implements a character buffer that can be used as a character-input stream. |
| CharArrayWriter | This class implements a character buffer that can be used as an Writer. |
| Console | Methods to access the character-based console device, if any, associated with the current Java virtual machine. |
| DataInputStream | A data input stream lets an application read primitive Java data types from an underlying input stream in a machine-independent way. |
| DataOutputStream | A data output stream lets an application write primitive Java data types to an output stream in a portable way. |
| File | An abstract representation of file and directory pathnames. |
| FileDescriptor | Instances of the file descriptor class serve as an opaque handle to the underlying machine-specific structure representing an open file, an open socket, or another source or sink of bytes. |
| FileInputStream | A FileInputStream obtains input bytes from a file in a file system. |
| FileOutputStream | A file output stream is an output stream for writing data to a File or to a FileDescriptor. |
| FilePermission | This class represents access to a file or directory. |
| FileReader | Reads text from character files using a default buffer size. |
| FileWriter | Writes text to character files using a default buffer size. |
| FilterInputStream | A FilterInputStream contains some other input stream, which it uses as its basic source of data, possibly transforming the data along the way or providing additional functionality. |
| FilterOutputStream | This class is the superclass of all classes that filter output streams. |
| FilterReader | Abstract class for reading filtered character streams. |
| FilterWriter | Abstract class for writing filtered character streams. |
| InputStream | This abstract class is the superclass of all classes representing an input stream of bytes. |
| InputStreamReader | An InputStreamReader is a bridge from byte streams to character streams: It reads bytes and decodes them into characters using a specified charset. |
| LineNumberInputStream | Deprecated. |
| This class incorrectly assumes that bytes adequately represent characters. | |
| LineNumberReader | A buffered character-input stream that keeps track of line numbers. |
| ObjectInputFilter.Config | A utility class to set and get the process-wide filter or create a filter from a pattern string. |
| ObjectInputStream | An ObjectInputStream deserializes primitive data and objects previously written using an ObjectOutputStream. |
| ObjectInputStream.GetField | Provide access to the persistent fields read from the input stream. |
| ObjectOutputStream | An ObjectOutputStream writes primitive data types and graphs of Java objects to an OutputStream. |
| ObjectOutputStream.PutField | Provide programmatic access to the persistent fields to be written to ObjectOutput. |
| ObjectStreamClass | Serialization’s descriptor for classes. |
| ObjectStreamField | A description of a Serializable field from a Serializable class. |
| OutputStream | This abstract class is the superclass of all classes representing an output stream of bytes. |
| OutputStreamWriter | An OutputStreamWriter is a bridge from character streams to byte streams: Characters written to it are encoded into bytes using a specified charset. |
| PipedInputStream | A piped input stream should be connected to a piped output stream; the piped input stream then provides whatever data bytes are written to the piped output stream. |
| PipedOutputStream | A piped output stream can be connected to a piped input stream to create a communications pipe. |
| PipedReader | Piped character-input streams. |
| PipedWriter | Piped character-output streams. |
| PrintStream | A PrintStream adds functionality to another output stream, namely the ability to print representations of various data values conveniently. |
| PrintWriter | Prints formatted representations of objects to a text-output stream. |
| PushbackInputStream | A PushbackInputStream adds functionality to another input stream, namely the ability to push back or unread bytes, by storing pushed-back bytes in an internal buffer. |
| PushbackReader | A character-stream reader that allows characters to be pushed back into the stream. |
| RandomAccessFile | Instances of this class support both reading and writing to a random access file. |
| Reader | Abstract class for reading character streams. |
| SequenceInputStream | A SequenceInputStream represents the logical concatenation of other input streams. |
| SerializablePermission | This class is for Serializable permissions. |
| StreamTokenizer | The StreamTokenizer class takes an input stream and parses it into tokens, allowing the tokens to be read one at a time. |
| StringBufferInputStream | Deprecated. |
| This class does not properly convert characters into bytes. | |
| StringReader | A character stream whose source is a string. |
| StringWriter | A character stream that collects its output in a string buffer, which can then be used to construct a string. |
| Writer | Abstract class for writing to character streams. |