public boolean isUsed(long pos,int length){
  int start=getBlock(pos);
  int blocks=getBlockCount(length);
  for (int i=start; i < start + blocks; i++) {
    if (!set.get(i)) {
      return false;
    }
  }
  return true;
}

public boolean isUsed ( long pos , int length ) { int start = getBlock ( pos ) ; int blocks = getBlockCount ( length ) ; for ( int i = start ; i < start + blocks ; i ++ ) { if ( ! set . get ( i ) ) { return false ; } } return true ; }
check whether one of the blocks is in use .
