Name: apC94908 Date: 02/25/2000



Spec for java.io.Reader says:
---------------
public void mark(int readAheadLimit)
          throws IOException

     Mark the present position in the stream. Subsequent calls to reset() will attempt to
     reposition the stream to this point. Not all character-input streams support the mark()
     operation.
     Parameters:
          readAheadLimit - Limit on the number of characters that may be read while
          still preserving the mark. After reading this many characters, attempting to reset
          the stream may fail.
     Throws:
          IOException - If the stream does not support mark(), or if some other I/O error
                                      _______________________
          occurs
---------------

But it throws IOException on mark operation even if underlying
InputStream support mark - ByteArrayInputStream, for example

----- Test.java
import java.io.*;
public class Test {

    public static void main(String[] args) throws IOException {
        byte[] ba = new byte[10];
// InputStreamReader inherits mark from Reader
        InputStreamReader isr = new InputStreamReader(new
                ByteArrayInputStream(ba));
        isr.mark(5);
    }
}
----- Output
Exception in thread "main" java.io.IOException: mark() not supported
at java.io.Reader.mark(Reader.java:194)
at Test.main(Test.java:8)
-----

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