notsobad.java

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * Average Expense Calculator
 */
public class Average_Expense_Calculator {

    public Integer average(Map<String, List<Integer>> expenses) { //Using more strict types 

        Integer expenseSum = 0;
        //for (int i = 0; i < expenses.size(); i++) { // counter i should be incremented
        for(Map.Entry<String,List<Integer>> person:expenses.entrySet()) {

            //Map.Entry<String,Object> person = new ArrayList<>(expenses.entrySet()).get(i);

            int personalExpense = sum(person.getValue()); // sum up values for personal Expense

            System.out.println("Employee: " + person.getKey() + " Expense: " + personalExpense);

            expenseSum += personalExpense;
        }

        Integer average = expenseSum / expenses.size();

        return average;
    }

    public Integer sum(List<Integer> n) {
        int result = 0;
        for (Integer x : n) {
            result = result + x;
        }
        return result;
    }
}