Class InputStreamReader
- 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 specifiedcharset. 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(System.in));
- Since:
- JDK1.1
- See Also:
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BufferedReader,InputStream,Charset
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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
All Methods Instance Methods Concrete Methods Modifier and Type Method and Description voidclose()Closes the stream and releases any system resources associated with it.StringgetEncoding()Returns the name of the character encoding being used by this stream.intread()Reads a single character.intread(char[] cbuf, int offset, int length)Reads characters into a portion of an array.booleanready()Tells whether this stream is ready to be read.
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Constructor Detail
InputStreamReader
public InputStreamReader(InputStream in)
Creates an InputStreamReader that uses the default charset.- Parameters:
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in- An InputStream
InputStreamReader
public InputStreamReader(InputStream in, String charsetName) throws UnsupportedEncodingException
Creates an InputStreamReader that uses the named charset.- Parameters:
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in- An InputStream -
charsetName- The name of a supportedcharset - Throws:
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UnsupportedEncodingException- If the named charset is not supported
InputStreamReader
public InputStreamReader(InputStream in, Charset cs)
Creates an InputStreamReader that uses the given charset.- Parameters:
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in- An InputStream -
cs- A charset - Since:
- 1.4
InputStreamReader
public InputStreamReader(InputStream in, CharsetDecoder dec)
Creates an InputStreamReader that uses the given charset decoder.- Parameters:
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in- An InputStream -
dec- A charset decoder - Since:
- 1.4
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Method Detail
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 returnnullif the stream has been closed.- Returns:
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The historical name of this encoding, or
nullif the stream has been closed - See Also:
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Charset
read
public int read() throws IOExceptionReads a single character.- Overrides:
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readin classReader - Returns:
- 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 offset, int length) throws IOExceptionReads characters into a portion of an array.- Specified by:
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readin classReader - Parameters:
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cbuf- Destination buffer -
offset- Offset at which to start storing characters -
length- Maximum number of characters to read - Returns:
- The number of characters read, or -1 if the end of the stream has been reached
- Throws:
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IOException- If an I/O error occurs
ready
public boolean ready() throws IOExceptionTells 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:
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readyin 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:
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IOException- If an I/O error occurs
close
public void close() throws IOExceptionDescription copied from class:ReaderCloses 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:
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closein interfaceCloseable - Specified by:
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closein interfaceAutoCloseable - Specified by:
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closein classReader - Throws:
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IOException- If an I/O error occurs
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Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
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