CS 206 - Introduction to Data Structures

Lab 1

Unix and Visual Studio Code

Thursday, Jan 23

Part 1 Using Visual Studio Code to write Java programs

1. Start VSC
   1. Applications Menu / Programming / Code - OSS
   2. or Applications Menu / System Tools / Mate Terminal then in the terminal window enter the command "code &"
2. Check to confirms that the correct extension packs are installed
   1. Java Extension Pack
   2. PrintCode
3. In the window that appears (it should say "Welcome") tap on "Add Workspace folder" under "Start". (You will likely never need to do this step again.)
   1. In the list in on the left side of the popup, tap on "Home"
   2. In the upper right tap on the folder icon
   3. In the small popup, enter "cs206"
   4. Tap on "create"
   5. Tap on "Add"
4. Right click on "cs206" and select "Add Folder to Workspace". In the popup, tap on the folder with star icon in the upper right. In the little popup that appears name the folder "Lab1" then tap on "create". Finally, tap on "add"
5. Right click on "Lab1" and select "New File". Name the file "Hello World.java"
6. Tap on the HelloWorld.java tab
7. Write a complete java implementation of a "hello world" program.
8. Run your program (to run do the following).
   1. Tap on the insect on the left edge of the screen
   2. Tap on "Run with Java"

Part 2: UNIX

• cd
  Change directory
  Example: cd cs206 (change to the directory cs206)
  Example: cd .. (change to the directory one above where you are, for instance is you are in /home/xena/cs206, then cd .. would put you in /home/xena
  Example: cd with no argument. This returns you to your home directory
• ls
  Display all the files in the directory.
  Example: ls cs206 list the files in the directory cs206 (if it exists)
  Example: ls list the files in the current directory
• pwd
  Displays the current working directory

More Java

1. Modify your hello world program to print out "hello World" and the count (ie "Hello World 1", "Hello World 2") a lot for times. (At least 610). Do not do this using 610 print statements.
2. Run your program

Write a program to count the number of lines in a file.

1. Start a new Program in VSC
   1. Return to the document view by clicking on the overlapping rectangles (upper left)
   2. Ctrl-click (left click) on "Lab1" and select "new File". Name the file "EchoCount.java"
2. Tap on the EchoCount.java tab (you should already be on that tab).
3. Enter the following program:

   	public class EchoCount
   	{
   	    public static void main(String[] args) {
   	        new EchoCount().echo();
   	    }
   
   	    public EchoCount()
   	    {
   	    }
   
   	    public void echo()
   	    {
   	        try (BufferedReader br = new BufferedReader(new FileReader("/home/gtowell/Public206/lab01/descent.txt"));) {
   	            int lineCount=0;
   	            while (null!=br.readLine())
   	                lineCount++;
   	            System.out.println("Lines read " + lineCount);
   	        } catch (FileNotFoundException fnf) {
   	            System.err.println("Could not open the file" + fnf);
   			} catch (IOException ioe)
   	        {
   	            System.err.println("Reading problem" + ioe);
   	        }
   	    }
   	}	
   

4. After entering all of this, you should see many items with a squiggly red underscore; BufferedReader, FileReader, etc. The underscores indicate problems in your code. At each
   1. Position the cursor over the underscored text.
   2. A popup will appear, on the bottom line of the popup, tap on "Quick fix".
   3. Generally, this will suggest ways of fixing the problem. In these cases, the fix "Import". So select "import"
   4. The squiggly line should go away.
5. Run your program.
   1. Tap on the insect on the left edge of the screen
   2. Tap on "Run with Java"
6. Extend this program so that it prints the file being read in addition to printing the number of lines in the file.

Write a program to calculate the Fibonacci sequence.

1. Create a new Class in VSC
2. (If needed) Return to the document view by clicking on the overlapping rectangles (upper left)
3. Right click on "Lab1" and select "New File". Name the file "Fibonacci.java"
4. Tap on the Fibonacci.java tab (you should already be there)
5. Write a java program to compute the Fibonacci sequence and the golden mean (the golden mean is the ration between two consecutive fibonacci numbers i.e., nI/n(I-1)). Your program should be able to calculate the fibonacci sequence to an arbitrary length. For now, 20 will do. Your program should generate a table like:

   		1 1 1.0
   		1 2 2.0
   		2 3 1.5
   		3 5 1.6666666666666667
   		5 8 1.6
   		8 13 1.625
   		13 21 1.6153846153846154
   		21 34 1.619047619047619
   		34 55 1.6176470588235294
   		55 89 1.6181818181818182
   		89 144 1.6179775280898876
   		144 233 1.6180555555555556
   		233 377 1.6180257510729614
   		377 610 1.6180371352785146
   		610 987 1.618032786885246
   		987 1597 1.618034447821682
   		1597 2584 1.6180338134001253
   		2584 4181 1.618034055727554
   		4181 6765 1.6180339631667064
   		6765 10946 1.6180339985218033
   	

   Here is the the core code for computing the fibonacci sequence. You will need to write a more code to make this useful.

   		int n_2=1;
   		int n_1=1;
   		for (int i=1; i<20; i++) {
   			int nI = n_2 + n_1;
   			n_1 = n_2;
   			n_2 = nI;
   		}
   	

   When calculating the golden mean you will want to watch out for an issue with integer versus floating point division
6. Run your program.
   1. Tap on the insect on the left edge of the screen
   2. Tap on "Run with Java"