java.io

  • The java.io package provides a set of interfaces and classes for handling input and output operations in Java.

  • It includes classes for reading and writing data to files, streams, and other data sources.

  • The package supports various data types, including primitive types, objects, and characters.

  • It also provides functionalities such as buffering, filtering, and serialization of data.

  • Several exceptions and errors are defined to handle potential I/O issues.

Interfaces

Closeable A Closeable is a source or destination of data that can be closed. 
DataInput The DataInput interface provides for reading bytes from a binary stream and reconstructing from them data in any of the Java primitive types. 
DataOutput The DataOutput interface provides for converting data from any of the Java primitive types to a series of bytes and writing these bytes to a binary stream. 
Externalizable Only the identity of the class of an Externalizable instance is written in the serialization stream and it is the responsibility of the class to save and restore the contents of its instances. 
FileFilter A filter for abstract pathnames. 
FilenameFilter Instances of classes that implement this interface are used to filter filenames. 
Flushable A Flushable is a destination of data that can be flushed. 
ObjectInput Defines an interface for classes that allow reading serialized objects. 
ObjectInputValidation A callback interface for post-deserialization checks on objects. 
ObjectOutput Defines an interface for classes that allow reading serialized objects. 
ObjectStreamConstants A helper interface with constants used by the serialization implementation. 
Serializable Serializability of a class is enabled by the class implementing the java.io.Serializable interface. 

Classes

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 Provides access to the console, if available. 
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 Legacy security code; do not use. 
FileReader Convenience class for reading character files. 
FileWriter Convenience class for writing character files. 
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 This class is deprecated. This class incorrectly assumes that bytes adequately represent characters. As of JDK 1.1, the preferred way to operate on character streams is via the new character-stream classes, which include a class for counting line numbers.  
LineNumberReader A buffered character-input stream that keeps track of line numbers. 
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 A class for turning a character stream into a byte stream. 
PipedInputStream Receives information from a communications pipe. 
PipedOutputStream Places information on 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" one byte. 
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 legacy security is not supported on Android. 
SerialVersionUIDDigest Dynamically loaded implementation for computing serialVersionUID hashes. 
StreamTokenizer Parses a stream into a set of defined tokens, one at a time. 
StringBufferInputStream This class is deprecated. This class does not properly convert characters into bytes. As of JDK 1.1, the preferred way to create a stream from a string is via the StringReader class.  
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. 

Exceptions

CharConversionException Base class for character conversion exceptions. 
EOFException Signals that an end of file or end of stream has been reached unexpectedly during input. 
FileNotFoundException Signals that an attempt to open the file denoted by a specified pathname has failed. 
InterruptedIOException Signals that an I/O operation has been interrupted. 
InvalidClassException Thrown when the Serialization runtime detects one of the following problems with a Class. 
InvalidObjectException Indicates that one or more deserialized objects failed validation tests. 
IOException Signals that an I/O exception of some sort has occurred. 
NotActiveException Thrown when serialization or deserialization is not active. 
NotSerializableException Thrown when an instance is required to have a Serializable interface. 
ObjectStreamException Superclass of all exceptions specific to Object Stream classes. 
OptionalDataException Exception indicating the failure of an object read operation due to unread primitive data, or the end of data belonging to a serialized object in the stream. 
StreamCorruptedException Thrown when control information that was read from an object stream violates internal consistency checks. 
SyncFailedException Signals that a sync operation has failed. 
UncheckedIOException Wraps an IOException with an unchecked exception. 
UnsupportedEncodingException The Character Encoding is not supported. 
UTFDataFormatException Signals that a malformed string in modified UTF-8 format has been read in a data input stream or by any class that implements the data input interface. 
WriteAbortedException Signals that one of the ObjectStreamExceptions was thrown during a write operation. 

Errors

IOError Thrown when a serious I/O error has occurred.