Chapter 12 Exercise 25, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

12.25 (Process large dataset)
A university posts its employees’ salaries at
http:// cs.armstrong.edu/liang/data/Salary.txt.
Each line in the file consists of a faculty member’s first name, last name,
rank, and salary (see Programming Exercise 12.24). Write a program to display
the total salary for assistant professors, associate professors, full professors,
and all faculty, respectively, and display the average salary for assistant professors,
associate professors, full professors, and all faculty, respectively.

import java.net.URL;
import java.util.ArrayList;
import java.util.Scanner;

public class Exercise_25 {

    private static final int ASSI = 0; // ASSISTANT
    private static final int ASSO = 1; // ASSOCIATE
    private static final int FULL = 2;

    public static void main(String[] args) throws Exception {

        ArrayList<ArrayList<Double>> allRanks = new ArrayList<>(3);
        allRanks.add(ASSI, new ArrayList<>());
        allRanks.add(ASSO, new ArrayList<>());
        allRanks.add(FULL, new ArrayList<>());

        URL url = new URL("http://cs.armstrong.edu/liang/data/Salary.txt");
        Scanner input = new Scanner(url.openStream());


        while (input.hasNext()) {
            String firstName = input.next();
            String lastName = input.next();
            String rank = input.next();
            if (rank.contains("assistant")) {
                allRanks.get(ASSI).add(input.nextDouble());
            } else if (rank.contains("associate")) {
                allRanks.get(ASSO).add(input.nextDouble());
            } else {
                allRanks.get(FULL).add(input.nextDouble());
            }
        }

        long assiTotal = (long)getTotal(allRanks.get(ASSI).toArray());
        long assoTotal = (long)getTotal(allRanks.get(ASSO).toArray());
        long fullTotal = (long)getTotal(allRanks.get(FULL).toArray());
        long total = assiTotal + assoTotal + fullTotal;
        System.out.println("Assistant total = " + assiTotal);
        System.out.println("Associate total = " + assoTotal);
        System.out.println("Full total = " + fullTotal);
        System.out.println("All Total = " + total);
        System.out.printf("Assistant average = %.2f \n", getAverage(assiTotal, allRanks.get(ASSI).size()));
        System.out.printf("Associate average = %.2f \n", getAverage(assoTotal, allRanks.get(ASSO).size()));
        System.out.printf("Full average = %.2f \n", getAverage(fullTotal, allRanks.get(FULL).size()));
        System.out.printf("All average = %.2f \n", getAverage(total, getInternalSize(allRanks)));



    }

    private static double getTotal(Object[] objects) {
        double total = 0;
        for (Object o : objects) {
            total += (double)o;
        }
        return total;
    }

    private static int getInternalSize(ArrayList<ArrayList<Double>> lists) {

        int size = 0;
        for (ArrayList<Double> list : lists) {
            size += list.size();
        }

        return size;
    }

    private static double getAverage(long total, int size) {

        return (double)total / size;
    }
}