Revised assessment test for AccessCode -- now converted into a solution.

Unit0Exercises.java

package nyc.c4q;

import java.io.FileReader;
import java.util.HashMap;

public class Unit0Exercises {
    /*
     * Name of the method implies what the method should do.
     * Some of these methods require that the method return signature change.
     * For example, `returnPrimitiveBooleanTrue()` should return `boolean`, not `Object`.
     * additional information in the comments of each method
     */
    public static void main (String args[]) {
        // Use main to test your methods
        print();
    }

    public static void print() {
        // print out "I'm sorry Dave, I'm afraid I can't let you do that."
        System.out.println("I'm sorry Dave, I'm afraid I can't let you do that.");
    }

    public static boolean returnPrimitiveBooleanFalse() {
        return false;
    }

    public static int returnPrimitiveInt55Plus44() {
        return 55+44;
    }

    public static double returnPrimitiveDouble2Point718() {
        // This is the start of a famous mathematical constant.
        // What's that constant?
        return 2.718;
    }

    public static char returnPrimitiveCharASCII35() {
        // What's the character for the ASCII number 35?
        // Look at an ASCII table and return that character.
        // You can look at the ASCII table at http://www.asciitable.com/
        return (char) 35;
    }

    public static boolean isEven(int n) {
        return n % 2 == 0;
    }

    public static boolean isMultipleOfX(int n, int x) {
        // 0 is a multiple of every number (except 0)
        // For example:
        //      isMultipleOfX(0, 3) == true
        //      isMultipleOfX(1, 3) == false
        //      isMultipleOfX(3, 3) == true
        //      isMultipleOfX(10, 3) == false
        //      isMultipleOfX(28, 7) == true
        //      isMultipleOfX(-14, 7) == true
        // Don't worry about when x==0

        return n % x == 0;
    }

    public static int returnSumOfOddNumbersBetween1And100() {
        // Starts with [1, 3, 5, ...]
        // Ends with   [..., 95, 97, 99]

        int total = 0;
        int current = 1;
        while (current < 100) {
            total += current;
            current += 2;
        }

        return total;
    }

    public static int returnSumOfTheFirst200MultiplesOf3() {
        // Starts with [0, 3, 6, ...]
        // Ends with   [..., 591, 594, 597]

        int total = 0;
        int current = 0;
        while (current < 200) {
            total += current * 3;
            current += 1;
        }

        return total;
    }

    public static boolean isEmptyString(String s) {
        return s.equals("");
    }

    public static String alternateS1AndS2Xtimes(String s1, String s2, int x) {
        // Given string `s1`, `s2` and a positive integer `x`,
        // return a string that is equal to s1 + s2 repeated x times.
        // If x is 0 or negative negative, return an empty string `""`.
        // For example:
        //      alternateS1AndS2Xtimes("abra", "cadabra", 0).equals("") == true
        //      alternateS1AndS2Xtimes("abra", "cadabra", 1).equals("abracadabra") == true
        //      alternateS1AndS2Xtimes("abra", "cadabra", 2).equals("abracadabraabracadabra") == true
        //      alternateS1AndS2Xtimes("abra", "cadabra", 3).equals("abracadabraabracadabraabracadabra") == true

        String newString = "";
        for (int i=0; i<x; i++){
            newString += s1;
            newString += s2;
        }
        return newString;
    }

    public static String stringSplit(String s, String splitOn) {
        // Given string s, return a string that stops at the first occurrence of "split".
        // For example:
        //      stringSplit("ubiquitous", "q").equals("ubi") == true
        //      stringSplit("hellogoodbye", "good").equals("hello") == true
        //      stringSplit("fancy seeing you", "there").equals("") == true
        // If the string does not contain split, then return the empty string "".
        String[] results = s.split(splitOn);
        if (results.length == 1) // couldn't split, so keeps the original string
            return "";
        else
            return results[0];
    }

    public static HashMap<String, Singer> returnSingers() {
        // should return a HashMap of the following singers:
        //      key="Beyonce",  Singer(name="Beyonce", location="USA")
        //      key="Jay-Z",    Singer(name="Jay-Z",   location="USA")
        //      key="Bieber",   Singer(name="Bieber",  location="Canada")
        //      key="Drake",    Singer(name="Drake",   location="Canada")
        //      key="Jepsen",   Singer(name="Jepsen",  location="Canada")
        HashMap<String, Singer> people = new HashMap<>();
        people.put("Beyonce", new Singer("Beyonce", "USA"));
        people.put("Jay-Z", new Singer("Jay-Z", "USA"));
        people.put("Bieber", new Singer("Bieber", "Canada"));
        people.put("Drake", new Singer("Drake", "Canada"));
        people.put("Jepsen", new Singer("Jepsen", "Canada"));

        return people;
    }

    public static boolean isFromCanada(Singer person) {
        return person.getLocation().equals("Canada");
    }

    public static void changeJayZsLocationToLosAngeles(HashMap<String, Singer> people) {
        // people will have the values of the `returnSingers()` method you filled in previously.
        // the city should be set to "Los Angeles"
        // old value of Jay-Z:
        //      Singer(name="Jay-Z",   location="USA")
        // new value of Jay-Z:
        //      Singer(name="Jay-Z",   location="Los Angeles")

        people.get("Jay-Z").setLocation("Los Angeles");
    }

    public static void removeJepsenFromSingers(HashMap<String, Singer> people){
        // people will have the values of the `returnSingers()` method you filled in previously.
        // old keys in `people`:
        //  ["Beyonce", "Jay-Z", "Bieber", "Drake", "Jepsen"]
        // new keys in `people`:
        //  ["Beyonce", "Jay-Z", "Bieber", "Drake"]

        people.remove("Jepsen");

    }

    // Bonus Problems
    public static void readFileAndOnlyPrintCanadianCelebrities() throws Exception {
        // TODO Use Apache Commons CSV and provide boilerplate for reading the file
        // https://commons.apache.org/proper/commons-csv/
        FileReader fr = new FileReader("celebrities.csv");
    }

    public static void readFileAndPrintCelebrityAges(){
        // TODO similar as above
    }
}