InputStreamReader

public class InputStreamReader extends Reader
Known Direct Subclasses

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(System.in));
 

Inherited Field Summary

Public Constructor Summary

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 Method Summary

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 offset, int length)
Reads characters into a portion of an array.
boolean
ready()
Tells whether this stream is ready to be read.

Inherited Method Summary

Public Constructors

public InputStreamReader (InputStream in)

Creates an InputStreamReader that uses the default charset.

Parameters
in An InputStream

public InputStreamReader (InputStream in, String charsetName)

Creates an InputStreamReader that uses the named charset.

Parameters
in An InputStream
charsetName The name of a supported charset
Throws
UnsupportedEncodingException If the named charset is not supported

public InputStreamReader (InputStream in, Charset cs)

Creates an InputStreamReader that uses the given charset.

Parameters
in An InputStream
cs A charset

public InputStreamReader (InputStream in, CharsetDecoder dec)

Creates an InputStreamReader that uses the given charset decoder.

Parameters
in An InputStream
dec A charset decoder

Public Methods

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

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(InputStream, 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
  • The historical name of this encoding, or null if the stream has been closed
See Also

public int read ()

Reads a single character.

Returns
  • The character read, or -1 if the end of the stream has been reached
Throws
IOException If an I/O error occurs

public int read (char[] cbuf, int offset, int length)

Reads characters into a portion of an array.

Parameters
cbuf Destination buffer
offset Offset at which to start storing characters
length 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

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
  • 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