HW 8 Solution

This homework has 3 problems which deal with sets and maps (Ch 21).







Eclipse Reminder




You will create a Java Project in Eclipse with the name: hw8_FLastname
You will have three packages: prob1, prob2, prob3









Problem 1




Do Programming Exercise 21-1 on page 818 from the text. Create a prob1 package and add a new class named Exercise21_1. Note, the problem says to use LinkedHashSet, you can use HashSet if you like. However, there is absolutely no difference between the two in terms of this problem. The output should look like this:




Original Set 1: [George, Jim, John, Blake, Kevin, Michael]




Original Set 2: [George, Katie, Kevin, Michelle, Ryan]




Union of the two sets: [George, Jim, John, Blake, Kevin, Michael, Katie, Michelle, Ryan]

Difference of the two sets: [Jim, John, Blake, Michael]




Intersection of the two sets: [George, Kevin]










Hint: 1. To clone a Set set1, you may use the following code:




LinkedHashSet<String set1Clone1 = (LinkedHashSet<String)set1.clone();




2. Use the Collection methods: addAll, removeAll and retainAll







Problem 2




A HashMap holds the points scored (value) for each player (key) in game 1. A similar HashMap holds the points scored for each player in game 2. For example:




HashMap<String,Integer game1 = new HashMap<();




game1.put("Chen", 4);

game1.put("Allie", 9);




game1.put("Reece", 4);




game1.put("Skuye", 6);

game1.put("Meshell", 6);




HashMap<String,Integer game2 = new HashMap<();




game2.put("Chen", 8);

game2.put("Zyrene", 4);




game2.put("Skuye", 2);




game2.put("Meshell", 3);




1

Do the following:




Create a package named, “prob2” and a class named, “Games”.



Write a method named getTotals that accepts two HashMaps as described above and returns a TreeMap of all the players that played in both games and the total number of points they got. For the example above, the result is:



Key=Chen, Value=12




Key=Meshell, Value=9

Key=Skuye, Value=8




Write a main with the maps above, call getTotals, and print the resulting TreeMap as shown immediately above.









Problem 3




Do the following:




Create a package named, “prob3” and a class named, “Games2”.
Create a Player class and add this code:



public class Player {

private String name;




private int points;




public Player(String name, int points) {




this.name = name;

this.points = points;




}




public String getName() {

return name;




}




public int getPoints() {

return points;




}




@Override

public String toString() {




return "name=" + name + ", points=" + points;




}

}




3. Define a TreeSet in main to hold Player objects sorted by name, then points. Test with this code:




Player p1 = new Player("Benito", 33);




Player p2 = new Player("Quincy", 14);




Player p3 = new Player("Lean", 22);

Player p4 = new Player("Carly", 41);




Player p5 = new Player("Pepper", 18);







2

// Add your code to define TreeSet named "team" here




team.addAll(Arrays.asList(p1,p2,p3,p4,p5)); System.out.println("\nPlayers sorted by name:"); for(Player p : team) System.out.println(p);




Hint: You need to implement and use a Comparator, NameComparator, to sort players by name, then points, in a TreeSet







Write a method named getPlayersAbove that accepts a TreeSet of Player objects and an integer, val. The method should return a set of Players containing only the players with points at or above val.



Hints:




You need to implement and use a Comparator, PointsComparator, to sort players by points, then name, in a TreeSet



Create a “dummy” player with points val and use the method tailSet on TreeSet to return a set of all players that are larger than or equal to the “dummy” player in terms of points.



Add the code below to the bottom of main to test:



Set<Player big = getPlayersAbove(team,20);




System.out.println("\nPlayers with a lot of points:"); for(Player p : big) System.out.println(p);







The excepted outcome is as follows:




Players sorted by name:

name=Benito, points=33




name=Carly, points=41

name=Lean, points=22




name=Pepper, points=18

name=Quincy, points=14




Players sorted by points:




name=Quincy, points=14




name=Pepper, points=18

name=Lean, points=22




name=Benito, points=33

name=Carly, points=41




Players with a lot of points:

name=Lean, points=22




name=Benito, points=33

name=Carly, points=41













Submission




Make sure you zip the ENTIRE folder hw8_FLastname!! Submit your zip file to Blazeview by the due date. The name of your file should be: hw8_FLastname.zip.







Grading




I will RANDOMLY select one problem for grading. For example, if problem 1 is selected, I will only go to the package/folder prob1 for grading. So make sure all your Java codes are in the correct packages/folders.










Additional Requirements:







No late submission will be accepted.
Please exactly follow the naming rules described above. You will be deducted 10 points for incorrect naming.



Write comments at the beginning of your Java source file(s) to indicate your name, student ID, “CS 1302-A Homework 8”, and the due date.



Make sure that your programs are well-documented, readable, and user friendly. Make sure you document your programs by adding comments to your statements/blocks so that I can understand your code. You will get 0 to 10 points based on the helpfulness of your comments. You will be deducted 10 points for no comments.



It is your responsibility to make sure your programs can compile and run correctly. Please be aware that programs that do not compile may receive ZERO credit.



When grades are returned to you via BlazeView, you have 7 days to meet with the instructor to discuss on grade changes. After 7 days, the grades are written in stone and can't be changed after that point.















































































































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