public InputStream() 
{
        /* empty */
}

This constructor does nothing. It is provided for signature compatibility.

 public int available() throws IOException 
{
        return 0;
}

Returns the number of bytes that are available before this stream will block. This implementation always returns 0. Subclasses should override and indicate the correct number of bytes available.

 public  void close() throws IOException 
{
        /* empty */
}

Closes this stream. Concrete implementations of this class should free any resources during close. This implementation does nothing.

 public  void mark(int readlimit) 
{
        /* empty */
}

Sets a mark position in this InputStream. The parameter {@code readlimit} indicates how many bytes can be read before the mark is invalidated. Sending {@code reset()} will reposition the stream back to the marked position provided {@code readLimit} has not been surpassed.

This default implementation does nothing and concrete subclasses must provide their own implementation.

 public boolean markSupported() 
{
        return false;
}

Indicates whether this stream supports the {@code mark()} and {@code reset()} methods. The default implementation returns {@code false}.

 abstract public int read() throws IOException
Reads a single byte from this stream and returns it as an integer in the
range from 0 to 255. Returns -1 if the end of the stream has been
reached. Blocks until one byte has been read, the end of the source
stream is detected or an exception is thrown.

 public int read(byte[] b) throws IOException 
{
        return read(b, 0, b.length);
}

Reads bytes from this stream and stores them in the byte array {@code b}.

 public int read(byte[] b,
    int offset,
    int length) throws IOException 
{
        // Force null check for b first!
        if (offset  > b.length || offset <  0) {
            // luni.12=Offset out of bounds \: {0}
            throw new ArrayIndexOutOfBoundsException(Messages.getString("luni.12", offset)); //$NON-NLS-1$
        } 
        if (length <  0 || length  > b.length - offset) {
            // luni.18=Length out of bounds \: {0}
            throw new ArrayIndexOutOfBoundsException(Messages.getString("luni.18", length)); //$NON-NLS-1$
        }
        for (int i = 0; i <  length; i++) {
            int c;
            try {
                if ((c = read()) == -1) {
                    return i == 0 ? -1 : i;
                }
            } catch (IOException e) {
                if (i != 0) {
                    return i;
                }
                throw e;
            }
            b[offset + i] = (byte) c;
        }
        return length;
}

Reads at most {@code length} bytes from this stream and stores them in the byte array {@code b} starting at {@code offset}.

 public synchronized  void reset() throws IOException 
{
        throw new IOException();
}

Resets this stream to the last marked location. Throws an {@code IOException} if the number of bytes read since the mark has been set is greater than the limit provided to {@code mark}, or if no mark has been set.

This implementation always throws an {@code IOException} and concrete subclasses should provide the proper implementation.

 public long skip(long n) throws IOException 
{
        if (n < = 0) {
            return 0;
        }
        long skipped = 0;
        int toRead = n <  4096 ? (int) n : 4096;
        // We are unsynchronized, so take a local copy of the skipBuf at some
        // point in time.
        byte[] localBuf = skipBuf;
        if (localBuf == null || localBuf.length <  toRead) {
            // May be lazily written back to the static. No matter if it
            // overwrites somebody else's store.
            skipBuf = localBuf = new byte[toRead];
        }
        while (skipped <  n) {
            int read = read(localBuf, 0, toRead);
            if (read == -1) {
                return skipped;
            }
            skipped += read;
            if (read <  toRead) {
                return skipped;
            }
            if (n - skipped <  toRead) {
                toRead = (int) (n - skipped);
            }
        }
        return skipped;
}

Skips at most {@code n} bytes in this stream. It does nothing and returns 0 if {@code n} is negative. Less than {@code n} characters are skipped if the end of this stream is reached before the operation completes.

This default implementation reads {@code n} bytes into a temporary buffer. Concrete subclasses should provide their own implementation.