Class InputStreamReader
- All Implemented Interfaces:
Closeable
,AutoCloseable
,Readable
- Direct Known Subclasses:
FileReader
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));
- Since:
- 1.1
- See Also:
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Field Summary
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Constructor Summary
ConstructorDescriptionCreates an InputStreamReader that uses thedefault 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. -
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Closes the stream and releases any system resources associated with it.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.boolean
ready()
Tells whether this stream is ready to be read.Methods declared in class java.io.Reader
mark, markSupported, nullReader, read, read, reset, skip, transferTo
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Constructor Details
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InputStreamReader
Creates an InputStreamReader that uses thedefault charset
.- Parameters:
in
- An InputStream- See Also:
-
InputStreamReader
Creates an InputStreamReader that uses the named charset.- Parameters:
in
- An InputStreamcharsetName
- The name of a supportedcharset
- Throws:
UnsupportedEncodingException
- If the named charset is not supported
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InputStreamReader
Creates an InputStreamReader that uses the given charset.- Parameters:
in
- An InputStreamcs
- A charset- Since:
- 1.4
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InputStreamReader
Creates an InputStreamReader that uses the given charset decoder.- Parameters:
in
- An InputStreamdec
- A charset decoder- Since:
- 1.4
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Method Details
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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 returnnull
if the stream has been closed.- Returns:
- The historical name of this encoding, or
null
if the stream has been closed - See Also:
-
read
Reads a single character.- Overrides:
read
in classReader
- Returns:
- The character read, or -1 if the end of the stream has been reached
- Throws:
IOException
- If an I/O error occurs
-
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 and0
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 intocbuf
.- Specified by:
read
in classReader
- Parameters:
cbuf
- Destination bufferoff
- Offset at which to start storing characterslen
- Maximum number of characters to read- Returns:
- The number of characters read, or -1 if the end of the stream has been reached
- Throws:
IndexOutOfBoundsException
- Ifoff
is negative, orlen
is negative, orlen
is greater thancbuf.length - off
IOException
- If an I/O error occurs
-
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.- Overrides:
ready
in classReader
- 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
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close
Description copied from class:Reader
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.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Specified by:
close
in classReader
- Throws:
IOException
- If an I/O error occurs
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