Homework 10

Due: 11:59 pm on Sunday, November 7, 2004 (M/T sections)
or 11:59 pm on Monday, November 8, 2004 (W/Th sections)

Reading: CS 5 notes, week 10

2 problems, 20 points for #1 and 30 points for #2

Problem 1 Connect Four [topics: practice with Classes and Objects]

Connect four is a variation of tic-tac-toe played on a rectangular board:

The game is played by two players, alternating turns, with each trying to place four checkers in a row vertically, horizontally, or diagonally. One constraint in the game is that because the board stands vertically, the checkers can not be placed in any position. A checker may only be placed at the top of one of the currently existing columns (or it may start a new column).

The Board class -- a preview

In this problem, you will need to create a class named Board that implements some of the features of the Connect Four game. The Board class will have three data members: there will be a 2d array of chars to represent the game area, an int holding the number of rows, and an int holding the number of columns. The details of the Board class appear after a description of what main in the CS5App class should do.

The CS5App class

The main method of the CS5App class will allow two people to play the game. (Next week's assignment will ask you to write an automated player that will take on human -- or computer -- opponents.)

The players will be represented by characters -- the player to go first will be represented by 'X' (a capital X) and the player to go second will be 'O' (a capital O).

Your main method inside the CS5App class should do the following:

First, welcome the user(s) to your Connect Four program.

Second, enter the height and width of the board the user would like to use. You should make sure the height and width are each greater than or equal to 4 and each less than or equal to 15.

Third, you should create a Board object of the requested size (using the constructor from the Board class).

Then, enter a loop that alternates between the players' turns:
- printing the board
- prompting the correct player for a move
- checking that the move is valid -- when it is, you should
- make that move for the player
- check if the game is over
- continue or stop, as appropriate
- switch players if you are continuing

There are no additional required methods to write in the CS5App class

Required Data Members to have in the Board class

Your Board class should have three data members:
- private char[ ][ ] data;
- private int nrows;
- private int ncols;

private

Board

data

characters

Methods required for the Board class Some are provided in the zip file... .

public Board(int rows, int cols) (provided)

This is a constructor for Board objects that takes two input arguments: the number of rows (rows) and the number of columns (cols). Inside this constructor, you should set the values of all three data members of the Boardobject, including the definition of data as a new 2d array of the appropriate size. Also, you should go through this 2d char array and initialize each element to ' ', the space character.

public void print() (provided)

This method prints the Board object that calls it. Here is an example from a 6-row, 7-column Board: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |O| |O| | | | |X|X|X|O| | | --------------- 0 1 2 3 4 5 6 Basically, each "checker" takes up one space and all columns are separated by vertical bars (|). The columns are labeled at the bottom. When the label numbers reach double digits, you should only print the final digit (the user will be able to tell which column in which). For example, here is a 6-row, 15-column board: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ------------------------------- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 See the example run for more examples of what the board should look like as a game is played.

public boolean allowsMove(int c)

This method should return true if the calling Board object can allow a move into column c (because there is space available). It returns false if c does not have space available or if it is not a valid column. Thus, this method should check to be sure that c is within the range from 0 to the last column and make sure that there is still room left in that column!

public void addMove(int c, char player) (provided)

This method should add a player's checker into column c. Note that the code will have to find the highest row number available in column c and put the checker in that row. The highest row number available is the first row with a space character ' ' in column c. Notice that the hoghest row number corresponds to the lowest physical row on the board.

public boolean winsFor(char player)

This method should return true if the calling Board is a winner for the character player. It should return false otherwise. You may assume that player will be an 'X' or an 'O'. Important Note: you need to check if the player has won horizontally, vertically, or diagonally. There are two directions for a diagonal win: from NW to SE and from NE to SW.

public boolean isFull()

This method should return true if the calling Board is completely full, tha is, if there are no spaces left for additional moves. Otherwise, it should return false.

Sample Run

Welcome to Connect Four!

Please enter the number of rows and columns you would 
like the game board to have (between 4 and 15 inclusive):  6 6


| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
-------------
 0 1 2 3 4 5

X's choice:  3

| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | |X| | |
-------------
 0 1 2 3 4 5

O's choice:  4

| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | |X|O| |
-------------
 0 1 2 3 4 5

X's choice:  2

| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | |X|X|O| |
-------------
 0 1 2 3 4 5

O's choice:  4

| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | |O| |
| | |X|X|O| |
-------------
 0 1 2 3 4 5

X's choice:  1

| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | | | |O| |
| |X|X|X|O| |
-------------
 0 1 2 3 4 5

O's choice:  2

| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | |O| |O| |
| |X|X|X|O| |
-------------
 0 1 2 3 4 5

X's choice:  0


X wins -- Congratulations!

| | | | | | |
| | | | | | |
| | | | | | |
| | | | | | |
| | |O| |O| |
|X|X|X|X|O| |
-------------
 0 1 2 3 4 5

Submission Be sure to submit your CS5App.java file under homework 10, problem 1.

Problem 2 Virtual Art! [topics: Writing a class and using objects]

For this problem, you'll be implementing Professor Art Benjamin (of HMC's math department). Among Prof. Benjamin's many talents is the ability to compute in his head facts about the calendar. (You should ask him what day of the week you were born some time...). In this problem, you'll write a program that will be able to stand in for Prof. Benjamin -- at least in terms of calendar computations -- during this year's sabbatical.

The Date class -- just a warning

This problem is the first in which you will need to write your own Java class. It should be named Date. This class should be placed in your CS5App.java file, outside of the CS5App.java class. The Date class should contain three data members and a few methods. All of the details are explained below, after an explanation of what should go in the CS5App class:

The CS5App class

Your main method inside the CS5App class should do the following:

First, welcome the user to your date-analysis program.

Second, enter the month, day, and year of a date the user is interested in. Create an object of the Date class representing that date. You may assume here and throughout that the user will input a valid date!

Then, enter a loop that always
(1) prints the date currently under consideration
(2) presents the user with the following menu:

      (0) Enter a new date of interest
      (1) Print the current date of interest
      (2) Move one day forward in time
      (3) Move one day backward in time
      (4) Day difference finder
      (5) Find the day of the week

      (9) Quit

      Which choice would you like?

Of course, you will need to implement the different options on this menu. In doing so you will need to use the following methods.

Additional required methods to write in the CS5App class

public static void printMenu()

This method should simply print out the above menu. The loop around this menu and inputting the user's choice should be handled in the main method.

The Date class -- data members

Your Date class should have three data members:
- private int month;
- private int day;
- private int year;
The private keyword in Java indicates that no other class will be able to access these data members directly.

The Date class -- required method to write

public Date(int m, int d, int y) (provided in class)

This is a constructor for Date objects that takes three input arguments: the month m, the day d, and the year y.

public void print() (provided in class)

This method should print out the Date object that calls it in the following familiar (month/day/year) format: 11/14/2001
public boolean isLeapYear() (provided in class)
public void yesterday()

This method should change the Date object that called it by moving it one day back in time. It should not prompt the user or print out anything (that will be done elsewhere). It should, however, take leap years into account. (See Notes #1 and #2 below.)

public void tomorrow()

This method should change the Date object that called it by moving it one day forward in time. It should not prompt the user or print out anything (that will be done elsewhere). Again, it should take leap years into account.

public boolean isBefore(Date d2)

This method should return true if the calling Date is earlier in time than the input argument d. It should return false otherwise.

public int diff(Date d2)

This method should return the number of days between the Date object that calls the method and the Date object d2 that is input. If d2 is later than the calling object, the result should be positive. If d2 is earlier than the calling object, the result should be negative.

Important Requirement: Your code MUST print out all of the intermediate days that you encounter when using diff as d2 gets closer and closer to "this." Printing the intermediate days and checking against the dates below will thoroughly check your code for correctness!

public int diffNoPrinting(Date d2)

This method does the same thing as diff, but does NOT print the intermediate dates. One way to write this is to simply remove the print statements from a copy of diff AFTER you've thoroughly debugged it!

public String dayOfWeek()

This method should return a String that indicates the day of the week of the Date object that calls it. That is, this method returns one of the following Strings: "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", or "Sunday". This method should work by creating a new Date whose day of the week you already know. Then, it should call diffNoPrinting and take the result modulo 7 (% 7) to obtain the day of the week in question.

Sample Run

Here is an exmple run. Notice that the date is always printed out before the menu -- as a result, you don't have to print out the date an additional time after choosing options 1, 2, or 3. (Yes, this makes option #1 quite easy to implement!)

To save space, the menu has been replaced by <Menu Here> after the first couple of times:

Welcome to the date calculator...

Enter a date you're interested in.
  Enter a month (1-12): 10
  Enter a legal day (of that month): 28
  Enter a year: 1929

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

The date under consideration is  10/28/1929


(0) Enter a new date of interest
(1) Print the current date of interest
(2) Move one day forward in time
(3) Move one day backward in time
(4) Day difference finder
(5) Find the day of the week

(9) Quit

   Your choice:  1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

The date under consideration is  10/28/1929

<Menu Here>

   Your choice:  2

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

The date under consideration is  10/29/1929

<Menu Here>

   Your choice:  3

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

The date under consideration is  10/28/1929

<Menu Here>

   Your choice:  4

Enter another valid date:
  Enter a month (1-12): 11
  Enter a legal day (of that month): 1
  Enter a year: 2004

10/31/2004
10/30/2004
10/29/2004
... lots of dates omitted ...
10/30/1929
10/29/1929

Between 10/28/1929 and 11/1/2004 there are  27398  days.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

The date under consideration is  10/28/1929

<Menu Here>

   Your choice:  5

The date 10/28/1929 is a Monday.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

The date under consideration is  10/28/1929

<Menu Here>

   Your choice:  0

Enter a new date of interest:
  Enter a month (1-12): 7
  Enter a legal day (of that month): 4
  Enter a year: 2076

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

The date under consideration is  7/4/2076

<Menu Here>

   Your choice:  5

The date 7/4/2076 is a Saturday.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

The date under consideration is  7/4/2076

<Menu Here>

   Your choice:  4

Enter another valid date:
  Enter a month (1-12): 11
  Enter a legal day (of that month): 1
  Enter a year: 2004

11/2/2004
11/3/2004
... lots of dates omitted ...
7/3/2076
7/4/2076

Between 7/4/2076 and 11/1/2004 there are -26178 days.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

The date under consideration is  7/4/2076

<Menu Here>

   Your choice: 9

NOTE: Recall the rules for whether or not a year is a leap year:

If a year is divisible by 400, it is a leap year.
If a year is divisible by 100 (but not 400), it is NOT a leap year.
If a year is divisible by 4 (but not 100), it is a leap year.
If a year is not divisible by 4, it is NOT a leap year.

Submission Be sure to submit your CS5App.java file under homework 10, problem 2.

Extra Credit Mouse input for connect-four [topics: event-handling with graphical interfaces]

For extra credit this week, you may augment problem 1 so that the user can input a checker by clicking anywhere in the appropriate column with the mouse. Also, consider adding an animation that shows the "checker drop," as well as the "clear the board" effect that makes the physical game as appealing as it is... . Any other additions or capabilities are also welcome.

Important Note If you do this extra credit, do not submit it in place of Hw10 Pr1 -- instead, complete the regular connect-four problem and submit it, then work on this problem. Be sure to start from the third zip file, Hw10ExCr.zip, which has a hook so that you can access mouse information from the CS5App class.

Hints The Hw10ExCr.zip code has an extra method named handleMousePressed in CS5App. It is called whenever the mouse button is pressed, and it print the row and column coordinates of the mouse location -- note that they are doubles. Here is one way you might approach this:

Create three data members in the CS5App class. I made a boolean named madeAMove, a Board named b and an int named uc (user's choice). Only madeAMove was a new variable from the ordinary program -- the other two I simply pulled out of main to make them data members of the CS5App class.
When it is time to make a move inside main, instead go into a loop that simply waits for madeAMove to become true. Back in handleMousePressed, that variable should be set to true only if a valid move is made. You should have a short pause in your waiting-loop inside main, or it will hog the whole processor doing nothing... .
Then, then the waiting-loop stops (because madeAMove became true, proceed to add the checker to the Board b in main in the usual way.

There are a couple of other things to worry about, but that's why it's extra credit after all! - Good luck!