Java IO.pdf - Nguyen Dang Binh

15.4 The InputStreamReader Class
The most basic concrete subclass of Reader is InputStreamReader:
public class InputStreamReader extends Reader
The constructor connects a character reader to an underlying input stream:
public InputStreamReader(InputStream in)
public InputStreamReader(InputStream in, String encoding)
throws UnsupportedEncodingException
Java I/O
The first constructor uses the platform's default encoding, as given by the system property
file.encoding. The second one uses the specified encoding. For example, to attach an
InputStreamReader to System.in with the default encoding (generally ISO Latin-1):
InputStreamReader isr = new InputStreamReader(System.in);
If you want to read a file encoded in Latin-5 (ASCII plus Turkish, as specified by ISO 8859-
9), you might do this:
FileInputStream fin = new FileInputStream("symbol.txt");
InputStreamReader isr = new InputStreamReader(fin, "8859_9");
There's no easy way to determine which encodings are supported, but the ones listed in Table
B.4 are supported by most VMs.
The read() methods read bytes from an underlying input stream and convert those bytes to
characters according to the specified encoding:
public int read() throws IOException
public int read(char c[], int off, int length) throws IOException
The getEncoding() method returns a string containing the name of the encoding used by this
reader:
public String getEncoding()
The remaining two methods just override methods from java.io.Reader but behave
identically from the perspective of the programmer:
public boolean ready() throws IOException
public void close() throws IOException
Example 15.2 uses an InputStreamReader to read a file in a user-specified encoding. The
FileConverter reads the name of the input file, the name of the of the output file, the input
encoding, and the output encoding. Characters that are not available in the output character set
are replaced by the substitution character, generally the question mark.
365