Understanding Streams - Beginning Java 2 SDK - page 329

Stream Readers and Writers

Stream readers and writers are objects that can read and write byte streams as character streams. So a
character stream is essentially a byte stream fronted by a reader or a writer. The base classes for stream
readers and writers are:

Class Description

Reader The base class for reading a character stream.

Writer The base class for writing a character stream.

Reader and Writer are both abstract classes. The Reader and Writer classes and their subclasses
are not really streams themselves, but provide the methods you can use for reading and writing binary
streams as character streams. Thus, a Reader or Writer object is typically created using an underlying
InputStream or OutputStream object that encapsulates the connection to the external device,
which is the ultimate source or destination of the data.

Using Readers
The Reader class has the direct subclasses shown in the diagram below:

Reader

InputStreamReader PipedReader

For Reading a Character Stream For Reading from a PipedWriter

BufferedReader CharArrayReader

For Buffering other Readers For Reading from a Char Array

StringReader

FilterReader

For Reading Filtered Streams For Reading from a String

The concrete class that you would use to read a binary input stream as a character stream is
InputStreamReader . You could create an InputStreamReader object like this:

InputStreamReader keyboard = new InputStreamReader(System.in);

The parameter to the InputStreamReader constructor is of type InputStream , so you can pass an
object of any class derived from InputStream to it. The sample above creates an
InputStreamReader object, keyboard , from the object System.in , the keyboard input stream.