private void unshareMain(){
  int[] old=_mainHash;
  int len=_mainHash.length;
  _mainHash=new int[len];
  System.arraycopy(old,0,_mainHash,0,len);
  _mainHashShared=false;
}

private void unshareMain ( ) { int [ ] old = _mainHash ; int len = _mainHash . length ; _mainHash = new int [ len ] ; System . arraycopy ( old , 0 , _mainHash , 0 , len ) ; _mainHashShared = false ; }
method that needs to be called , if the main hash structure is ( may be ) shared . this happens every time something is added , even if addition is to the collision list ( since collision list index comes from lowest 8 bits of the primary hash entry )
