InputStreamReader

public class InputStreamReader
extends Reader

java.lang.Object
   ↳ java.io.Reader
     ↳ java.io.InputStreamReader


An InputStreamReader is a bridge from byte streams to character streams: It reads bytes and decodes them into characters using a specified charset. The charset that it uses may be specified by name or may be given explicitly, or the platform's default charset 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(anInputStream));
 

Summary

Inherited fields

Public constructors

InputStreamReader(InputStream in)

Creates an InputStreamReader that uses the default charset.

InputStreamReader(InputStream in, String charsetName)

Creates an InputStreamReader that uses the named charset.

InputStreamReader(InputStream in, Charset cs)

Creates an InputStreamReader that uses the given charset.

InputStreamReader(InputStream in, CharsetDecoder dec)

Creates an InputStreamReader that uses the given charset decoder.

Public methods

void close()

Closes the stream and releases any system resources associated with it.

String getEncoding()

Returns the name of the character encoding being used by this stream.

int read()

Reads a single character.

int read(char[] cbuf, int off, int len)

Reads characters into a portion of an array.

int read(CharBuffer target)

Attempts to read characters into the specified character buffer.

boolean ready()

Tells whether this stream is ready to be read.

Inherited methods

Public constructors

InputStreamReader

Added in API level 1
public InputStreamReader (InputStream in)

Creates an InputStreamReader that uses the default charset.

Parameters
in InputStream: An InputStream

InputStreamReader

Added in API level 1
public InputStreamReader (InputStream in, 
                String charsetName)

Creates an InputStreamReader that uses the named charset.

Parameters
in InputStream: An InputStream

charsetName String: The name of a supported charset

Throws
UnsupportedEncodingException If the named charset is not supported

InputStreamReader

Added in API level 1
public InputStreamReader (InputStream in, 
                Charset cs)

Creates an InputStreamReader that uses the given charset.

Parameters
in InputStream: An InputStream

cs Charset: A charset

InputStreamReader

Added in API level 1
public InputStreamReader (InputStream in, 
                CharsetDecoder dec)

Creates an InputStreamReader that uses the given charset decoder.

Parameters
in InputStream: An InputStream

dec CharsetDecoder: A charset decoder

Public methods

close

Added in API level 1
public void close ()

Closes the stream and releases any system resources associated with it. Once the stream has been closed, further read(), ready(), mark(), reset(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect.

Throws
IOException

getEncoding

Added in API level 1
public String getEncoding ()

Returns the name of the character encoding being used by this stream.

If the encoding has an historical name then that name is returned; otherwise the encoding's canonical name is returned.

If this instance was created with the InputStreamReader(java.io.InputStream, java.lang.String) constructor then the returned name, being unique for the encoding, may differ from the name passed to the constructor. This method will return null if the stream has been closed.

Returns
String The historical name of this encoding, or null if the stream has been closed

See also:

read

Added in API level 1
public int read ()

Reads a single character.

Returns
int The character read, or -1 if the end of the stream has been reached

Throws
IOException If an I/O error occurs

read

Added in API level 1
public int read (char[] cbuf, 
                int off, 
                int len)

Reads characters into a portion of an array. This method will block until some input is available, an I/O error occurs, or the end of the stream is reached.

Parameters
cbuf char: Destination buffer

off int: Offset at which to start storing characters

len int: Maximum number of characters to read

Returns
int The number of characters read, or -1 if the end of the stream has been reached

Throws
IndexOutOfBoundsException
IOException

read

Added in API level 1
public int read (CharBuffer target)

Attempts to read characters into the specified character buffer. The buffer is used as a repository of characters as-is: the only changes made are the results of a put operation. No flipping or rewinding of the buffer is performed.

Parameters
target CharBuffer: the buffer to read characters into

Returns
int The number of characters added to the buffer, or -1 if this source of characters is at its end

Throws
IOException

ready

Added in API level 1
public boolean ready ()

Tells 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.

Returns
boolean True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.

Throws
IOException If an I/O error occurs