public String toString(){
        String ch=null;
        ch="la case "+abs+" "+ord+",";
        
        if (stock.size()==0 && habitant.size()==0)
        	ch+=" vide ";
        
        else{
        	ch+=" contient :"; 
        	if (stock.size()!=0 )
        	for(int i=0;i<stock.size();i++){
        		ch+=stock.get(i).toString();
        	}
        	if(habitant.size()!=0)
        	for(int j=0;j<habitant.size();j++){
        		ch+=habitant.get(j).toString();       
        	}
        }
        return ch;
    }