JavaTM 2 Platform
Std. Ed. v1.3.1

java.io
Class InputStreamReader

java.lang.Object
  |
  +--java.io.Reader
        |
        +--java.io.InputStreamReader
Direct Known Subclasses:
FileReader

public class InputStreamReader
extends Reader

An InputStreamReader is a bridge from byte streams to character streams: It reads bytes and translates them into characters according to a specified character encoding. The encoding that it uses may be specified by name, or the platform's default encoding may be accepted.

Each invocation of one of an InputStreamReader's read() methods may cause one or more bytes to be read from the underlying byte-input stream. To enable the efficient conversion of bytes to characters, more bytes may be read ahead from the underlying stream than are necessary to satisfy the current read operation.

For top efficiency, consider wrapping an InputStreamReader within a BufferedReader. For example:

 BufferedReader in
   = new BufferedReader(new InputStreamReader(System.in));
 

Since:
JDK1.1
See Also:
BufferedReader, InputStream, Character encodings

Fields inherited from class java.io.Reader
lock
 
Constructor Summary
InputStreamReader(InputStream in)
          Create an InputStreamReader that uses the default character encoding.
InputStreamReader(InputStream in, String enc)
          Create an InputStreamReader that uses the named character encoding.
 
Method Summary
 void close()
          Close the stream.
 String getEncoding()
          Returns the canonical name of the character encoding being used by this stream.
 int read()
          Read a single character.
 int read(char[] cbuf, int off, int len)
          Read characters into a portion of an array.
 boolean ready()
          Tell whether this stream is ready to be read.
 
Methods inherited from class java.io.Reader
mark, markSupported, read, reset, skip
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

InputStreamReader

public InputStreamReader(InputStream in)
Create an InputStreamReader that uses the default character encoding.
Parameters:
in - An InputStream

InputStreamReader

public InputStreamReader(InputStream in,
                         String enc)
                  throws UnsupportedEncodingException
Create an InputStreamReader that uses the named character encoding.
Parameters:
in - An InputStream
enc - The name of a supported character encoding
Throws:
UnsupportedEncodingException - If the named encoding is not supported
Method Detail

getEncoding

public String getEncoding()
Returns the canonical name of the character encoding being used by this stream. If this InputStreamReader was created with the InputStreamReader(InputStream, String) constructor then the returned encoding name, being canonical, may differ from the encoding name passed to the constructor. May return null if the stream has been closed.
Returns:
a String representing the encoding name, or possibly null if the stream has been closed
See Also:
Character encodings

read

public int read()
         throws IOException
Read a single character.
Overrides:
read in class Reader
Returns:
The character read, or -1 if the end of the stream has been reached
Throws:
IOException - If an I/O error occurs

read

public int read(char[] cbuf,
                int off,
                int len)
         throws IOException
Read characters into a portion of an array.
Overrides:
read in class Reader
Parameters:
cbuf - Destination buffer
off - Offset at which to start storing characters
len - Maximum number of characters to read
Returns:
The number of characters read, or -1 if the end of the stream has been reached
Throws:
IOException - If an I/O error occurs

ready

public boolean ready()
              throws IOException
Tell whether this stream is ready to be read. An InputStreamReader is ready if its input buffer is not empty, or if bytes are available to be read from the underlying byte stream.
Overrides:
ready in class Reader
Throws:
IOException - If an I/O error occurs

close

public void close()
           throws IOException
Close the stream.
Overrides:
close in class Reader
Throws:
IOException - If an I/O error occurs

JavaTM 2 Platform
Std. Ed. v1.3.1

Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

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