package jet.util;

import java.io.*;
// written by zhangk
public interface RandomAccessable{
    /**
     * Sets the offset from the beginning at which the next 
     * read or write occurs. 
     *
     * @param      pos   the absolute position.
     * @exception  IOException  if an I/O error occurs.
    */
    public void seek(long pos) throws IOException;
    
    /**
     * Returns the current offset
     *
     * @return     the offset from the beginning, in bytes,
     *             at which the next read or write occurs.
     * @exception  IOException  if an I/O error occurs.
    */
    public long getPosition() throws IOException;

    /**
     * Skips exactly n bytes of input from current pos to pos+n.
     * return to skip 
     * @param      n   the number of bytes to be skipped.
     * @return     the number of bytes skipped, which is always <code>n</code>.
     * @exception  EOFException  if this file reaches the end before skipping
     *               all the bytes.
     * @exception  IOException  if an I/O error occurs.
    */
    public int skipBytes(int n) throws IOException;
    
    /**
     * Returns the length
     *
     * @return     the length
     * @exception  IOException  if an I/O error occurs.
     */
    public long length()throws IOException;
}