- java.lang.Object
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- java.io.Reader
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- java.io.InputStreamReader
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- All Implemented Interfaces:
- Closeable, AutoCloseable, Readable
- Direct Known Subclasses:
- FileReader
public class InputStreamReader extends Reader
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.charset
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));
- Since:
- JDK1.1
- See Also:
BufferedReader
,InputStream
,Charset
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Field Summary
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Fields inherited from class java.io.Reader
lock
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Constructor Summary
Constructors Constructor and Description InputStreamReader(InputStream in)
Creates an InputStreamReader that uses the default 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.InputStreamReader(InputStream in, String charsetName)
Creates an InputStreamReader that uses the named charset.
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Method Summary
Methods Modifier and Type Method and Description 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.
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Constructor Detail
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InputStreamReader
public InputStreamReader(InputStream in)
Creates an InputStreamReader that uses the default charset.- Parameters:
in
- An InputStream
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InputStreamReader
public InputStreamReader(InputStream in, String charsetName) throws UnsupportedEncodingException
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
public InputStreamReader(InputStream in, Charset cs)
Creates an InputStreamReader that uses the given charset.- Parameters:
in
- An InputStreamcs
- A charset- Since:
- 1.4
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InputStreamReader
public InputStreamReader(InputStream in, CharsetDecoder dec)
Creates an InputStreamReader that uses the given charset decoder.- Parameters:
in
- An InputStreamdec
- A charset decoder- Since:
- 1.4
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Method Detail
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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(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:
Charset
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read
public int read() throws IOException
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
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read
public int read(char[] cbuf, int offset, int length) throws IOException
Reads characters into a portion of an array.- Specified by:
read
in classReader
- Parameters:
cbuf
- Destination bufferoffset
- Offset at which to start storing characterslength
- 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
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ready
public boolean ready() throws IOException
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
public void close() throws IOException
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 interfaceCloseable
- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in classReader
- Throws:
IOException
- If an I/O error occurs
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Document created the 11/06/2005, last modified the 04/03/2020
Source of the printed document:https://www.gaudry.be/en/java-api-rf-java/io/InputStreamReader.html
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