Programming IT 2019-2020
Assessed Exercise 2
Dr. Simon Rogers & Prof. Alice Miller Connect 4
Connect 4 is a popular game played by two players. It consists of a board which is made up of X columns, into which counters can be dropped. When dropped, they come to rest at the bottom of the column (if it is empty), or on top of the last counter to be dropped into that column if it is not empty. Each column can contain a maximum of Y counters.
Each player uses counters of a different colour.
The objective of the game is to place your counters such that they make a line of four. A line can be horizontal, vertical, or diagonal. For example, in the board depicted below (with X = 7 columns numbered 0 to 6, and Y = 6 rows), if it were the red player’s turn, dropping a counter into column 4 would win them the game (creating a diagonal line of 4). If it were the yellow player’s turn, dropping a counter into column 1 would win them the game (creating a vertical line of 4).
Figure 1
In this assessed exercise you will build the objects necessary to create a connect 4 game. The game will be played by two players, each of whom is assigned a character, through the console, with the current state of the board displayed via printing a series of characters like this:
Figure 2
Tasks
As well as the classes listed below, you should create a class that holds a main method (and the static method described in task 4) called ConnectFour.java. Ensure your name and matric are given within comments in every class you submit. Code should be commented.
1. Players and counters [total: 5 marks]
a. Create a class to represent a game player. It should have an attribute to store
the player’s name (String) and an attribute to store their counter symbol
(char), both set via a constructor. [1 mark]
b. Create a class to represent a game counter. It should have only one
attribute: a reference to the player object that it belongs to, set by a
constructor. [1 mark]
c. Both classes should have getters and toString methods such that the
following code would produce the output “Clive, x” [2 marks]:
Player p1 = new Player(”Clive”,’x’);
Counter c = new Counter(p1); System.out.println(c.getPlayer().toString() + ”, “ + c.toString());
d. Define a boolean equals method in your Counter class that returns true if, when it is passed another Object, the other object is a Counter from the same Player. [1 mark]
2. Columns [total: 7 marks]
a. Create a class to represent a column. It should have a numRows attribute
that is set by the constructor. It should have an array with numRows elements that can store Counter objects. Note that the top of the column in the game will be represented by position 0 in your array, and the bottom (i.e. the position the first counter would fall into) will be position numRows-1. [2 marks]
b. Your class should have a boolean method called isFull that returns true if the column is full. [1 mark]
c. Your class should have an add method that takes as its arguments a Counter object and returns a boolean (true or false). If the column is not full, the Counter should be added to the correct position and the method should return true. If the column is full, the method should return false. If you test your Column with the following code it should give the output “true, true, true, true, false”: [2 marks]
Column col = new Column(4); for(int i=0;i<5;i++) {
Boolean result = col.add(new Counter(p1));
System.out.println(result);
}
d. Give your Column class a method called displayRow that takes a row number as an argument. Assume that the row number is always within an acceptable range. The method should return a String consisting of the counter’s character if there is a counter at that position and a String including a space character if there is no counter in that position. [1 mark]
e. Give your Column class a display method that displays each row on a separate line, using the displayRow method. If you test your code with the following example below, it should produce the following output: [1 mark] x
o x o x o
Column col = new Column(6);
Player p1 = new Player("Clive",'o'); Player p2 = new Player("Sharon",'x'); for(int i=0;i<3;i++) {
col.add(new Counter(p1));
col.add(new Counter(p2)); }
col.display();
3. Create a class to represent a Board. The class should [total: 5 marks]:
a. take a number of rows and columns in its constructor (in that order). [1 mark] b. have a boolean add method that takes a reference to a Counter object and a
column number as arguments (in that order) and returns true if the board
successfully adds the counter to that column, and false otherwise. [1 mark] c. Have a toString method that produces a String representation of the board
as shown in Figure 2 (above). [1 mark]
d. You can test your Board c lass using the following code that should give the
output shown in the Figure 2 above. [1 mark]
Board board = new Board(6,7);
Player p1 = new Player("Clive",'o'); Player p2 = new Player("Sharon",'x'); board.add(new Counter(p2),6); board.add(new Counter(p1),3); board.add(new Counter(p2),4); board.add(new Counter(p1),4); board.add(new Counter(p2),5); board.add(new Counter(p1),5); board.add(new Counter(p2),6); board.add(new Counter(p1),5); board.add(new Counter(p2),6); board.add(new Counter(p1),6);
e. Add a method to your Board class (isFull) that returns true if the board is full and false otherwise. [1 mark]
4. Write a static method (in your ConnectFour class) in which two players play randomly (i.e. they randomly choose columns until they find one that isn’t full) until the board is full. [total: 2 marks]
5. Winners (this is more advanced and a good pass can be achieved by skipping this part) [total: 3 marks]
a. Add a method to Board that checks if a player has won. Hint: first write a method that checks if, from a particular position, a line (either horizontal, vertical, or diagonal) of Z counters (where Z will typically equal 4) belonging to the same player exists. Then wrap this in a loop over all positions. Feel free to add methods to other classes as necessary. Code should be clearly commented to describe how it works.
What should you submit?
- A single .zip file containing your .java files. If you’re not sure how to make a .zip file, let us know. Please only use .zip and not .rar, .7z, or any other archiving program.
- This should be uploaded to Moodle by the deadline provided on Moodle.