bundles/org.tukani.xz/src/org/tukaani/xz/SeekableXZInputStream.java
public void seek(long pos) throws IOException {
        if (in == null)
            throw new XZIOException("Stream closed");

        if (pos < 0)
            throw new XZIOException("Negative seek position: " + pos);

        seekPos = pos;
        seekNeeded = true;
    }
public void seek(long pos) throws IOException {
        if (in == null)
            throw new XZIOException("Stream closed");

        if (pos < 0)
            throw new XZIOException("Negative seek position: " + pos);

        seekPos = pos;
        seekNeeded = true;
    }
Seeks to the specified absolute uncompressed position in the stream.
This only stores the new position, so this function itself is always
very fast. The actual seek is done when <code>read</code> is called
to read at least one byte.
<p>
Seeking past the end of the stream is possible. In that case
<code>read</code> will return <code>-1</code> to indicate
the end of the stream.

@param       pos         new uncompressed read position

@throws      XZIOException
if <code>pos</code> is negative, or
if stream has been closed