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));
See also:
Summary
Public constructors | |
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InputStreamReader(InputStream in)
Creates an InputStreamReader that uses the
|
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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 | |
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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. |
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Public constructors
InputStreamReader
public InputStreamReader (InputStream in)
Creates an InputStreamReader that uses the
default charset
.
Parameters | |
---|---|
in |
InputStream : An InputStream |
See also:
InputStreamReader
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
public InputStreamReader (InputStream in, Charset cs)
Creates an InputStreamReader that uses the given charset.
Parameters | |
---|---|
in |
InputStream : An InputStream |
cs |
Charset : A charset |
InputStreamReader
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
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
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
public int read ()
Reads a single character.
Returns | |
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int |
The character read, or -1 if the end of the stream has been reached |
Throws | |
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IOException |
If an I/O error occurs |
read
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 | |
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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 |
read
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 | |
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target |
CharBuffer : the buffer to read characters into |
Returns | |
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int |
The number of characters added to the buffer, or -1 if this source of characters is at its end |
Throws | |
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IOException |
ready
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 | |
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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 | |
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IOException |
If an I/O error occurs |