OpenJDK 1.22 · java.io.InputStreamReader · APIdia, the JavaDoc alternative

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 default charset may be used.

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));

Field Summary

Modifier and Type	Field and Description
private final StreamDecoder	sd

Inherited from java.io.Reader:: lock

Constructor Summary

Access	Constructor and Description
public	InputStreamReader(InputStream An InputStream in) Creates an InputStreamReader that uses the `default charset`.
public	InputStreamReader(InputStream An InputStream in, String The name of a supported `charset` charsetName) Creates an InputStreamReader that uses the named charset.
public	InputStreamReader(InputStream An InputStream in, Charset A charset cs) Creates an InputStreamReader that uses the given charset.
public	InputStreamReader(InputStream An InputStream in, CharsetDecoder A charset decoder dec) Creates an InputStreamReader that uses the given charset decoder.

Method Summary

Modifier and Type	Method and Description
public void	close() Implements abstract java.io.Reader.close. Implements java.io.Closeable.close. Closes the stream and releases any system resources associated with it.
public String	Returns: The historical name of this encoding, or `null` if the stream has been closed getEncoding() Returns the name of the character encoding being used by this stream.
private static Object	lockFor(InputStreamReader reader) Return the lock object for the given reader's stream decoder.
public int	read(CharBuffer the buffer to read characters into target) Overrides java.io.Reader.read. Implements java.lang.Readable.read. Attempts to read characters into the specified character buffer.
public int	Returns: The character read, or -1 if the end of the stream has been reached read() Overrides java.io.Reader.read. Reads a single character.
public int	read(char[] Destination buffer cbuf, int Offset at which to start storing characters off, int Maximum number of characters to read len) Implements abstract java.io.Reader.read. Reads characters into a portion of an array.
public boolean	ready() Overrides java.io.Reader.ready. Tells whether this stream is ready to be read.

Inherited from java.io.Reader:: mark markSupported nullReader read reset skip transferTo

Field Detail

sd	back to summary
private final StreamDecoder sd

Constructor Detail

InputStreamReader back to summary

InputStreamReader	back to summary
public InputStreamReader(InputStream in) Creates an InputStreamReader that uses the `default charset`. Parameters in:InputStream An InputStream See Also `Charset#defaultCharset()`

public InputStreamReader(InputStream in)

Creates an InputStreamReader that uses the default charset.

Parameters

in:InputStream: An InputStream

See Also

Charset#defaultCharset()

InputStreamReader back to summary

InputStreamReader	back to summary
public InputStreamReader(InputStream in, String charsetName) throws UnsupportedEncodingException Creates an InputStreamReader that uses the named charset. Parameters in:InputStream An InputStream charsetName:String The name of a supported `charset` Exceptions UnsupportedEncodingException: If the named charset is not supported

public InputStreamReader(InputStream in, String charsetName) throws UnsupportedEncodingException

Creates an InputStreamReader that uses the named charset.

Parameters

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

Exceptions

UnsupportedEncodingException:: If the named charset is not supported

InputStreamReader	back to summary
public InputStreamReader(InputStream in, Charset cs) Creates an InputStreamReader that uses the given charset. Parameters in:InputStream An InputStream cs:Charset A charset Since 1.4

InputStreamReader

back to summary

public InputStreamReader(InputStream in, Charset cs)

Creates an InputStreamReader that uses the given charset.

Parameters

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

Since

1.4

InputStreamReader	back to summary
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 Since 1.4

InputStreamReader

back to summary

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

Since

1.4

Method Detail

close	back to summary
public void close() throws IOException Implements abstract java.io.Reader.close. Implements java.io.Closeable.close. Doc from java.io.Reader.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. Exceptions IOException: If an I/O error occurs

back to summary

public void close() throws IOException

Implements abstract java.io.Reader.close.

Implements java.io.Closeable.close.

Doc from java.io.Reader.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.

Exceptions

IOException:: If an I/O error occurs

getEncoding back to summary

getEncoding	back to summary
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:String The historical name of this encoding, or `null` if the stream has been closed See Also `Charset`

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:String: The historical name of this encoding, or null if the stream has been closed
See Also: Charset

lockFor	back to summary
private static Object lockFor(InputStreamReader reader) Return the lock object for the given reader's stream decoder. If the reader type is trusted then an internal lock can be used. If the reader type is not trusted then the reader object is the lock.

read	back to summary
public int read(CharBuffer target) throws IOException Overrides java.io.Reader.read. Implements java.lang.Readable.read. Doc from java.io.Reader.read. 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. If the length of the specified character buffer is zero, then no characters will be read and zero will be returned. Parameters target:CharBuffer the buffer to read characters into Returns:int The number of characters added to the buffer, possibly zero, or -1 if this source of characters is at its end Exceptions IOException: if an I/O error occurs

read

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public int read(CharBuffer target) throws IOException

Overrides java.io.Reader.read.

Implements java.lang.Readable.read.

Doc from java.io.Reader.read.

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. If the length of the specified character buffer is zero, then no characters will be read and zero will be returned.

Parameters

target:CharBuffer: the buffer to read characters into

Returns:int

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

Exceptions

IOException:: if an I/O error occurs

read	back to summary
public int read() throws IOException Overrides java.io.Reader.read. Reads a single character. Returns:int The character read, or -1 if the end of the stream has been reached Exceptions IOException: If an I/O error occurs

read

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public int read() throws IOException

Overrides java.io.Reader.read.

Reads a single character.

Returns:int

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

Exceptions

IOException:: If an I/O error occurs

read back to summary

read	back to summary
public int read(char[] cbuf, int off, int len) throws IOException Implements abstract java.io.Reader.read. Doc from java.io.Reader.read. 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. If `len` is zero, then no characters are read and `0` is returned; otherwise, there is an attempt to read at least one character. If no character is available because the stream is at its end, the value `-1` is returned; otherwise, at least one character is read and stored into `cbuf`. 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 Exceptions IOException: If an I/O error occurs IndexOutOfBoundsException: If `off` is negative, or `len` is negative, or `len` is greater than `cbuf.length - off`

public int read(char[] cbuf, int off, int len) throws IOException

Implements abstract java.io.Reader.read.

Doc from java.io.Reader.read.

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.

If len is zero, then no characters are read and 0 is returned; otherwise, there is an attempt to read at least one character. If no character is available because the stream is at its end, the value -1 is returned; otherwise, at least one character is read and stored into cbuf.

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

Exceptions

IOException:: If an I/O error occurs
IndexOutOfBoundsException:: If off is negative, or len is negative, or len is greater than cbuf.length - off

ready	back to summary
public boolean ready() throws IOException Overrides java.io.Reader.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 Doc from java.io.Reader.ready. 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 IOException: If an I/O error occurs

ready

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public boolean ready() throws IOException

Overrides java.io.Reader.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

Doc from java.io.Reader.ready.

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

IOException:: If an I/O error occurs

public Class InputStreamReader

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail