InputStreamReader (Java SE 10 & JDK 10 ) (original) (raw)
- java.io.Reader
- java.io.InputStreamReader
All Implemented Interfaces:
[Closeable](../../java/io/Closeable.html "interface in java.io"),[AutoCloseable](../../java/lang/AutoCloseable.html "interface in java.lang"),[Readable](../../java/lang/Readable.html "interface in java.lang")
Direct Known Subclasses:[FileReader](../../java/io/FileReader.html "class in java.io")
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 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(System.in));
Since:
1.1
See Also:
BufferedReader, InputStream, Charset
Field Summary
* ### Fields declared in class java.io.[Reader](../../java/io/Reader.html "class in java.io") `[lock](../../java/io/Reader.html#lock)`Constructor Summary
Constructors
Constructor Description InputStreamReader(InputStream in) Creates an InputStreamReader that uses the default 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
All Methods Instance Methods Concrete Methods
Modifier and Type Method Description 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. * ### Methods declared in class java.lang.[Object](../../java/lang/Object.html "class in java.lang") `[clone](../../java/lang/Object.html#clone%28%29), [equals](../../java/lang/Object.html#equals%28java.lang.Object%29), [finalize](../../java/lang/Object.html#finalize%28%29), [getClass](../../java/lang/Object.html#getClass%28%29), [hashCode](../../java/lang/Object.html#hashCode%28%29), [notify](../../java/lang/Object.html#notify%28%29), [notifyAll](../../java/lang/Object.html#notifyAll%28%29), [toString](../../java/lang/Object.html#toString%28%29), [wait](../../java/lang/Object.html#wait%28%29), [wait](../../java/lang/Object.html#wait%28long%29), [wait](../../java/lang/Object.html#wait%28long,int%29)` * ### Methods declared in class java.io.[Reader](../../java/io/Reader.html "class in java.io") `[close](../../java/io/Reader.html#close%28%29), [mark](../../java/io/Reader.html#mark%28int%29), [markSupported](../../java/io/Reader.html#markSupported%28%29), [read](../../java/io/Reader.html#read%28char%5B%5D%29), [read](../../java/io/Reader.html#read%28java.nio.CharBuffer%29), [reset](../../java/io/Reader.html#reset%28%29), [skip](../../java/io/Reader.html#skip%28long%29), [transferTo](../../java/io/Reader.html#transferTo%28java.io.Writer%29)`Constructor Detail
* #### InputStreamReader public InputStreamReader([InputStream](../../java/io/InputStream.html "class in java.io") in) Creates an InputStreamReader that uses the default charset. Parameters: `in` \- An InputStream * #### InputStreamReader public InputStreamReader([InputStream](../../java/io/InputStream.html "class in java.io") in, [String](../../java/lang/String.html "class in java.lang") charsetName) throws [UnsupportedEncodingException](../../java/io/UnsupportedEncodingException.html "class in java.io") Creates an InputStreamReader that uses the named charset. Parameters: `in` \- An InputStream `charsetName` \- The name of a supported[charset](../../java/nio/charset/Charset.html "class in java.nio.charset") Throws: `[UnsupportedEncodingException](../../java/io/UnsupportedEncodingException.html "class in java.io")` \- If the named charset is not supported * #### InputStreamReader public InputStreamReader([InputStream](../../java/io/InputStream.html "class in java.io") in, [Charset](../../java/nio/charset/Charset.html "class in java.nio.charset") cs) Creates an InputStreamReader that uses the given charset. Parameters: `in` \- An InputStream `cs` \- A charset Since: 1.4 * #### InputStreamReader public InputStreamReader([InputStream](../../java/io/InputStream.html "class in java.io") in, [CharsetDecoder](../../java/nio/charset/CharsetDecoder.html "class in java.nio.charset") dec) Creates an InputStreamReader that uses the given charset decoder. Parameters: `in` \- An InputStream `dec` \- A charset decoder Since: 1.4Method Detail
* #### getEncoding public [String](../../java/lang/String.html "class in java.lang") 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)](../../java/io/InputStreamReader.html#%3Cinit%3E%28java.io.InputStream,java.lang.String%29) 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: The historical name of this encoding, or`null` if the stream has been closed See Also: [Charset](../../java/nio/charset/Charset.html "class in java.nio.charset") * #### read public int read() throws [IOException](../../java/io/IOException.html "class in java.io") Reads a single character. Overrides: `[read](../../java/io/Reader.html#read%28%29)` in class `[Reader](../../java/io/Reader.html "class in java.io")` Returns: The character read, or -1 if the end of the stream has been reached Throws: `[IOException](../../java/io/IOException.html "class in java.io")` \- If an I/O error occurs * #### read public int read(char[] cbuf, int offset, int length) throws [IOException](../../java/io/IOException.html "class in java.io") Reads characters into a portion of an array. Specified by: `[read](../../java/io/Reader.html#read%28char%5B%5D,int,int%29)` in class `[Reader](../../java/io/Reader.html "class in java.io")` Parameters: `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: `[IOException](../../java/io/IOException.html "class in java.io")` \- If an I/O error occurs `[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang")` \- If an I/O error occurs * #### ready public boolean ready() throws [IOException](../../java/io/IOException.html "class in java.io") 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](../../java/io/Reader.html#ready%28%29)` in class `[Reader](../../java/io/Reader.html "class in java.io")` 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](../../java/io/IOException.html "class in java.io")` \- If an I/O error occurs
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