Added in API level 1

InputStreamReader

open class InputStreamReader : Reader

kotlin.Any
↳	java.io.Reader
	↳	java.io.InputStreamReader

Known Direct Subclasses FileReader FileReader Reads text from character files using a default buffer size.

An InputStreamReader is a bridge from byte streams to character streams: It reads bytes and decodes them into characters using a specified . 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

Public constructors
InputStreamReader(in: InputStream!) Creates an InputStreamReader that uses the default charset.
InputStreamReader(in: InputStream!, charsetName: String!) Creates an InputStreamReader that uses the named charset.
InputStreamReader(in: InputStream!, cs: Charset!) Creates an InputStreamReader that uses the given charset.
InputStreamReader(in: InputStream!, dec: CharsetDecoder!) Creates an InputStreamReader that uses the given charset decoder.

Public methods
open Unit	close()
open String!	getEncoding() Returns the name of the character encoding being used by this stream.
open Int	read() Reads a single character.
open Int	read(cbuf: CharArray!, off: Int, len: Int) Reads characters into a portion of an array.
open Int	read(target: CharBuffer!)
open Boolean	ready() Tells whether this stream is ready to be read.

Inherited functions

From class Reader Unit mark(readAheadLimit: Int) Marks the present position in the stream. Subsequent calls to reset() will attempt to reposition the stream to this point. Not all character-input streams support the mark() operation. Boolean markSupported() Tells whether this stream supports the mark() operation. The default implementation always returns false. Subclasses should override this method. Reader! nullReader() Returns a new Reader that reads no characters. The returned stream is initially open. The stream is closed by calling the close() method. Subsequent calls to close() have no effect. While the stream is open, the read(), read(char[]), read(char[], int, int), read(Charbuffer), ready(), skip(long), and transferTo() methods all behave as if end of stream has been reached. After the stream has been closed, these methods all throw IOException. The markSupported() method returns false. The mark() and reset() methods throw an IOException. The object used to synchronize operations on the returned Reader is not specified. Int read(cbuf: CharArray!) Reads characters into an array. This method will block until some input is available, an I/O error occurs, or the end of the stream is reached. Unit reset() Resets the stream. If the stream has been marked, then attempt to reposition it at the mark. If the stream has not been marked, then attempt to reset it in some way appropriate to the particular stream, for example by repositioning it to its starting point. Not all character-input streams support the reset() operation, and some support reset() without supporting mark(). Long skip(n: Long) Skips characters. This method will block until some characters are available, an I/O error occurs, or the end of the stream is reached. Long transferTo(out: Writer!) Reads all characters from this reader and writes the characters to the given writer in the order that they are read. On return, this reader will be at end of the stream. This method does not close either reader or writer. This method may block indefinitely reading from the reader, or writing to the writer. The behavior for the case where the reader and/or writer is asynchronously closed, or the thread interrupted during the transfer, is highly reader and writer specific, and therefore not specified. If an I/O error occurs reading from the reader or writing to the writer, then it may do so after some characters have been read or written. Consequently the reader may not be at end of the stream and one, or both, streams may be in an inconsistent state. It is strongly recommended that both streams be promptly closed if an I/O error occurs.

Inherited properties
From class Reader Any! lock The object used to synchronize operations on this stream. For efficiency, a character-stream object may use an object other than itself to protect critical sections. A subclass should therefore use the object in this field rather than this or a synchronized method.

Public constructors

InputStreamReader

Added in API level 1

InputStreamReader(in: InputStream!)

Creates an InputStreamReader that uses the default charset.

Parameters
in	InputStream!: An InputStream

See Also

• java.nio.charset.Charset#defaultCharset()

InputStreamReader

Added in API level 1

InputStreamReader(
    in: InputStream!, 
    charsetName: String!)

Creates an InputStreamReader that uses the named charset.

Parameters
in	InputStream!: An InputStream
charsetName	String!: The name of a supported charset

Exceptions
java.io.UnsupportedEncodingException	If the named charset is not supported

InputStreamReader

Added in API level 1

InputStreamReader(
    in: InputStream!, 
    cs: Charset!)

Creates an InputStreamReader that uses the given charset.

Parameters
in	InputStream!: An InputStream
cs	Charset!: A charset

InputStreamReader

Added in API level 1

InputStreamReader(
    in: InputStream!, 
    dec: CharsetDecoder!)

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

open fun close(): Unit

Exceptions
java.lang.Exception	if this resource cannot be closed
java.io.IOException	if an I/O error occurs

getEncoding

Added in API level 1

open fun getEncoding(): String!

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.

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

See Also

• java.nio.charset.Charset

read

Added in API level 1

open fun read(): Int

Reads a single character.

Return
Int	The character read, or -1 if the end of the stream has been reached

Exceptions
java.io.IOException	If an I/O error occurs

read

Added in API level 1

open fun read(
    cbuf: CharArray!, 
    off: Int, 
    len: Int
): Int

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	CharArray!: Destination buffer
off	Int: Offset at which to start storing characters
len	Int: Maximum number of characters to read

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

Exceptions
java.lang.IndexOutOfBoundsException

read

Added in API level 1

open fun read(target: CharBuffer!): Int

Parameters
cb	the buffer to read characters into
target	CharBuffer!: the buffer to read characters into

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

Exceptions
java.io.IOException	if an I/O error occurs
java.lang.NullPointerException	if target is null
java.nio.ReadOnlyBufferException	if target is a read only buffer

ready

Added in API level 1

open fun ready(): Boolean

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.

Return
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.

Exceptions
java.io.IOException	If an I/O error occurs