Interview: Design an iterator for a collection of collections

Question

Design an iterator for a collection of collections in java. The iterator should hide the nesting, allowing you to iterate all of the elements belonging to all of the collect

Answer 1

if all you have to work with is the java Iterator: which just have hasNext(), next() and remove(), i figured you have to go around it.

Process it as you will process a 2D array, that is, with an outer and inner loop, because they have same "arrangement" but different datatype. As you process, you transfer them to a new collection.

so maybe a private method:

    private void convertToSingleCollection()
    {


         while("column")
         {
            //convert the "column" to an arra


           for( "Row")
           {
            //add to newCollection here
           }

          //remove the processed column from CollectionOFcollection
         } 
    }
    //call the above method in your constructor


    public iterator Iterator()
    {
       newCollection.iterator();
    }

    public boolean hasNext()
    {
       return Iterator().hasNext()
    }

    public T next()
    {
       if(!hasNext())
       {
        //exception message or message
       }
       else
           //return "next"
    }

end

I hope this helps. There should be other ways to solve it i guess.