public int reactionsUpdate(Reaction A){
  
    int index=-1;
    int i=0;
    
    while( index==-1 && i<reactions.size() ){
    
      index = ( A.getID().equals( reactions.get(i).getID() ) )? i:-1;
      i++;
      
    }
    
    if(index==-1){
      reactions.add(A);
      index = reactions.size()-1;
    }
    
    A.setIntID(index);
    
    return index;
    
    
  }