CS125: Introduction to Programming Principles

What You Should Know

• Board Class -- This class is not part of JAVA, but has been created by the CS department in order to help young programmers understand certain concepts. Since it is not a part of JAVA, in order to use it you must either have the class files reference in Dr.Java's path, OR you must have a copy of the Board.class and Coordinate.class files in the directory the rest of your files that you are currently working on are located. A class file is essentially a .java file, such as the ones you have created, but is compiled. Once you are finished your java files and compile them you will also notice that your files have .class files. These are what Dr. Java runs. Therefore, if you make a change to your java file, but forget to recompile it, then when you run it Dr. Java will be using the old class file that you make have compiled previously. After you make a change you must click 'Compile' again so that Dr. Java makes a new class file which represents your current java file code. If the Board/Coordinate classes are properly setup (see these instructions if not done yet), then you can use the Board object much like you used the Scanner object. You would first declare and initialize it like we did above:
  

  
               Board aBoard;
  
  	     aBoard = new Board(4, 5);
  
  	     

  or, alternatively, a more short hand version is
  

  
               Board aBoard = new Board(4, 5);
  
  	     

  Notice that the parameters accepted when making a Board are different then those of the Scanner class. The Board class either accepts one integer value, or two integer values. Accepting one integer value creates a Board of height 1, but with a width of the specified integer. When you give it two integers, it creates a board using the two different integers. Now that the board is created, much like the Scanner object you can use a variety of methods on it, such as removePeg(int row, int col). An example of using the remove peg would be:
  

   
  
               aBoard.removePeg(3,2); // removes a peg from row 3, and column 2	     
  
  	     

  For a list of methods that can be used with Board objects please see the Board Documentation. This documentation is located under the Resources Page.


• System Output -- Java makes outputting content to the screen very easy. All you need to do is use the command System.out.println("A Message goes here"); This would output A Message goes here to the screen and then drop the cursor down a line. You can alternatively place variables (int, char, String, boolean, etc) that you have declared in place of the message. An example is given below:
  

  	     
  	     System.out.print("Hello"); // notice I am not using println, but rather print. What does this do?
  	     
  	     String aMessage = "World";
  	     
  	     System.out.println(aMessage);
  	     
  	     System.out.println(2); // outputing a number
  	     
  	     

  The above code would output:

  
  	     HelloWorld
  
  	     2