java.io: public class: InputStreamReader

java.io
public class: InputStreamReader [javadoc | source]

java.lang.Object
   java.io.Reader
      java.io.InputStreamReader

All Implemented Interfaces:
Closeable, Readable

Direct Known Subclasses:
FileReader

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));

Also see:

BufferedReader

InputStream

java.nio.charset.Charset

author: Mark - Reinhold

since: JDK1.1 -

Fields inherited from java.io.Reader:
lock

Constructor:

Constructor:
public InputStreamReader(InputStream in) { super(in); try { sd = StreamDecoder.forInputStreamReader(in, this, (String)null); // ## check lock object } catch (UnsupportedEncodingException e) { // The default encoding should always be available throw new Error(e); } } Creates an InputStreamReader that uses the default charset. Parameters: `in` - An InputStream
public InputStreamReader(InputStream in, String charsetName) throws UnsupportedEncodingException { super(in); if (charsetName == null) throw new NullPointerException("charsetName"); sd = StreamDecoder.forInputStreamReader(in, this, charsetName); } Creates an InputStreamReader that uses the named charset. Parameters: `in` - An InputStream `charsetName` - The name of a supported charset `Throws: UnsupportedEncodingException - If the named charset is not supported exception: UnsupportedEncodingException - If the named charset is not supported`
public InputStreamReader(InputStream in, Charset cs) { super(in); if (cs == null) throw new NullPointerException("charset"); sd = StreamDecoder.forInputStreamReader(in, this, cs); } Creates an InputStreamReader that uses the given charset. Parameters: `in` - An InputStream `cs` - A charset since: `1.4` - spec: `JSR-51` -
public InputStreamReader(InputStream in, CharsetDecoder dec) { super(in); if (dec == null) throw new NullPointerException("charset decoder"); sd = StreamDecoder.forInputStreamReader(in, this, dec); } Creates an InputStreamReader that uses the given charset decoder. Parameters: `in` - An InputStream `dec` - A charset decoder since: `1.4` - spec: `JSR-51` -

 public InputStreamReader(InputStream in) {
        super(in);
        try {
            sd = StreamDecoder.forInputStreamReader(in, this, (String)null); // ## check lock object
        } catch (UnsupportedEncodingException e) {
            // The default encoding should always be available
            throw new Error(e);
        }
}

Creates an InputStreamReader that uses the default charset.

Parameters:

in - An InputStream

 public InputStreamReader(InputStream in,
    String charsetName) throws UnsupportedEncodingException {
        super(in);
        if (charsetName == null)
            throw new NullPointerException("charsetName");
        sd = StreamDecoder.forInputStreamReader(in, this, charsetName);
}

Creates an InputStreamReader that uses the named charset.

Parameters:

in - An InputStream

charsetName - The name of a supported charset

Throws:
UnsupportedEncodingException - 
If the named charset is not supported
exception: UnsupportedEncodingException - 
If the named charset is not supported

 public InputStreamReader(InputStream in,
    Charset cs) {
        super(in);
        if (cs == null)
            throw new NullPointerException("charset");
        sd = StreamDecoder.forInputStreamReader(in, this, cs);
}

Parameters:

in - An InputStream

cs - A charset

since: 1.4 -

spec: JSR-51 -

 public InputStreamReader(InputStream in,
    CharsetDecoder dec) {
        super(in);
        if (dec == null)
            throw new NullPointerException("charset decoder");
        sd = StreamDecoder.forInputStreamReader(in, this, dec);
}

Parameters:

in - An InputStream

dec - A charset decoder

since: 1.4 -

spec: JSR-51 -

Method from java.io.InputStreamReader Summary:
close, getEncoding, read, read, ready

Methods from java.io.Reader:
close, mark, markSupported, read, read, read, read, ready, reset, skip

Methods from java.lang.Object:
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from java.io.InputStreamReader Detail:
public void close() throws IOException { sd.close(); }
public String getEncoding() { return sd.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 return `null` if the stream has been closed.
public int read() throws IOException { return sd.read(); } Reads a single character.
public int read(char[] cbuf, int offset, int length) throws IOException { return sd.read(cbuf, offset, length); } Reads characters into a portion of an array.
public boolean ready() throws IOException { return sd.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.

Method from java.io.InputStreamReader Detail:

 public  void close() throws IOException {
        sd.close();
}

 public String getEncoding() {
        return sd.getEncoding();
}

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 return null if the stream has been closed.

 public int read() throws IOException {
        return sd.read();
}

Reads a single character.

 public int read(char[] cbuf,
    int offset,
    int length) throws IOException {
        return sd.read(cbuf, offset, length);
}

Reads characters into a portion of an array.

 public boolean ready() throws IOException {
        return sd.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.