Lab 7: Arrays
CS 141: Introduction to Programming , Fall 2017

Overview

The goal of this lab is to:

• Give you experience working with 1D and 2D arrays.
• Give you experience with complex code composed of multiple methods.
• Provide another example of a game and how its code is structured.

Part 0: Practice with Arrays (this part will not be collected)

Many of the problems in the Basic Array Problems are similar to the methods you must implement below. Try to do the problems below first but if you have trouble, take a look at the solutions for the Basic Array Problems. Many of these basic problems will be covered in class and are also discussed in your text.

Once you are comfortable working with arrays, try the following exercise which examines temperature data for Salem.

• Create a Netbeans project containing main(). Download the class Temperatures.java and place in your project folder. Note, you may need to rename the package name to match your package name.

• The Temperatures class contains a member variable which is a 1D array of doubles containing the average July temperatures for Salem from 1903 to 2015. It also has a member variable containing the starting year, 1903. Several methods are given, but the code is incomplete.

  Your task is to complete these methods:

  1. calcAverage(): returns the average of all the temperatures
  2. calcMax(): returns the maximum of all the temperatures
  3. calcMin(): returns the minimum of all the temperatures
  4. toString(): returns a string that prints a list of (year, temperature) pairs, for example:

     year: 1903 temperature = 63.6
     year: 1904 temperature = 66.8
     year: 1905 temperature = 68.8
     year: 1906 temperature = 72.0
     ...
     year: 2012 temperature = 66.8
     year: 2013 temperature = 70.5
     year: 2014 temperature = 72.5
     year: 2015 temperature = 72.8
     

  5. graph(): Prints a graph of the data. Each row corresponds to a single year with the number of "*"s corresponding to the value of the temperature. That is, each "*" corresponds to 1 degree.

     The simplest approach to coding this is to round each temperature to an integer (e.g. 64.6 will become 65) and, using a loop, print the number of "*"s equal to this rounded temperature (e.g. draw 65 "*"s). The graph for the first 5 years should look like:

     
     Salem Mean July Temperatures
     1903:  63.6 ****************************************************************
     1904:  66.8 *******************************************************************
     1905:  68.8 *********************************************************************
     1906:  72.0 ************************************************************************
     1907:  67.6 ********************************************************************
      

• To test your program, execute the following code below in main. You can compare your output to output.txt.

  Temperatures t = new Temperatures();
  System.out.println("Average temperature is " + t.calcAverage()); // should be around 67
  System.out.println("Max temperature is " + t.calcMax()); // should be 72.8
  System.out.println("Min temperature is " + t.calcMin());  // should be 61.9
  t.graph();
  

  You are encouraged but not required to demo your completed Temperatures class to the instructor or lab assistant.

Part 2: TicTacToe

In the above program, you worked with an 1D array. In this part of the lab, you will work with a 2D array.

Instructions:

• You are to complete a program that plays TicTacToe where the board is stored as a 2D array of chars. A large part of the code is provided.
• Create an new Netbeans project with main(). In main, add only the code:

  TicTacToe tictactoe = new TicTacToe();
  tictactoe.play();

• Add the class file TicTacToe.java to your project. Netbeans will flag a lot of errors. Ignore these errors for the moment.
• Before beginning to code, carefully read both the comments and the code so you know what is going on! It provides another example of the control structure of a game.
• Most member variables are already included. The only member variable you need to add is for the board. All the code errors should go away once you create the 2D array of chars for the board.
• The output should look very similar to this sample output tictactoeOutput.txt. Note, the computer is not a very good player!
• The game loop in play() is already implemented for you. Note, it continues looping as long as the number of moves is less than 9 and no one has won. Each time through the loop, one of the players (user or computer) takes a turn. An if-statement is used to select the turn method (userTurn vs computerTurn). See the comments in the code.
• Start implementing the methods that don't rely on the other methods, testing thoroughly as you proceed. For example, it makes sense to start with initBoard() and printBoard() methods. Use tabs (\t) as a way to format the columns when printing the board. Test your methods by calling them from play().
• Pick whatever strategy you want to implement the computerTurn() method. It doesn't have to play intelligently. It just has to be sure to play in an empty space. However, try to build a little bit of smarts into it.
• Try generating the Javadoc based on the comments in the code. In Netbeans, go to the menu:

  Tools->Analyze Javadoc

  This will let you know if there are any errors in your Javadoc and also it will generate the Javadoc, placing it in dist/Javadoc folder of the project.

Deliverables

To receive full credit, you need to:

1. Make sure that your Java code:

   • Is well commented, including at the top of each file, your name, lab name, program name, date, brief description of what the class does.
   • Is well formatted, i.e. proper indentation and line returns.

2. Demonstrate:

   • Your TicTacToe game to the instructor or lab assistant.

   • Submit your TicTacToe.java to Wise as an attachment to Lab 7