public boolean replaceRef(Object oldRef,Object newRef) throws IOException {
  Integer value=(Integer)_refs.remove(oldRef);
  if (value != null) {
    _refs.put(newRef,value);
    return true;
  }
 else   return false;
}

public boolean replaceRef ( Object oldRef , Object newRef ) throws IOException { Integer value = ( Integer ) _refs . remove ( oldRef ) ; if ( value != null ) { _refs . put ( newRef , value ) ; return true ; } else return false ; }
replaces a reference from one object to another .
