java - Using an interface and dependency injection -

i have program needs read data number of sources. have several objects, each containing list of students , test scores. have class must extract information each object.

the problem must operate through interface. i.e.

public class total{       hashmap<string, integer> results;        scoresinterface si;       ...       void addscores(){          results.putall( si.getscores());       }  }  public interface scoresinterface{        public hashmap getscores(); }  public class scores implements scoresinterface{      hashmap<string, integer> results;      ...      public hashmap getscores(){             return results;       } } 

i hope code makes sense. total class needs access number of scores objects , collect information.

my question basically, how can let total class know objects of scores class? have thought adding function in total called setsource(scoresinterface a) , passing each new object of scores in. however, seems bit long winded. if there 100 objects.

thanks help

i pass in list<scoresinterface>.

that way use total class iterate through , calculate total.

the type of list implementation (arraylist, linkedlist etc..) you.