Sample Question:

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JSR Notes:

Sub-procedures In General

In general sub-procedures offer:

• Decomposition. By this we mean adopting a "divide and conquer" strategy - taking a big problem and dividing it into smaller do-able problems, or in the case of programming smaller, do-able methods.
  • Decomposition leads to better organization and easier overall understanding of a big problem.
• Abstraction. Abstraction in this case is basically ignoring other details and focusing on one part of the problem. With methods, one method can be worked on and tested in isolation from the others.

We will delve more into the benefits of decomposition and abstraction later on.

Java Methods

The teaching note refers to Java methods and the way we can access Java methods is by calling their name, i.e. their identifier.

Methods are, indeed,"named chunks of code". And so from that point on, when we want to run those lines of code we can identify them, i.e. call them, using their names, i.e. their identifiers. See the programming example below.

 

Non-Programming Example

Taking the classic "getting ready for school" example, we could take all of the major steps and make them into their own sub-procedures, i.e. methods. As follows:

• Get Cleaned Up Sub-procedure
  • Shower
  • Brush hair
  • Put on face cream
  • Brush teeth
• Get Dressed Sub-procedure
  • Choose & put on underwear
  • Choose & put on socks
  • Choose & put on pants/shorts
  • Choose & put on shirt
  • Choose & put on shoes
• Eat Breakfast Sub-procedure
  • Open fridge
  • Take out milk
  • etc. etc. etc.
• Get Stuff Ready to Take to School
  • Gather books needed that day
  • Gather laptop and other IT stuff
  • Gather after school activity/sports stuff if doing that that day
  • Put all your stuff in your backpack

 

Programming Example

15 public class ProjectForTopic4ProgrammingExamples {
16     static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
17     static int numHLCourses = 0;
18     static int numSLCourses = 0;
19     static double avgSLScore = 0.0;
20     static double avgHLScore = 0.0;
21     
22     public static void main(String[] args) throws Exception {
23         //HERE IS WHERE WE CAN SEE THE BREKING OF THE PROGRAM INTO SUB-PROCEDURES
24         initialUserInput();
25         doSL();
26         doHL();
27         finalCalcuationsAndResults();   
28     }  
29     
30     public static void initialUserInput(){
31         System.out.println("How many HL courses are you taking?");
32         numHLCourses = Integer.parseInt(br.readLine());
33         System.out.println("How many SL courses are you taking?");
34         numSLCourses = Integer.parseInt(br.readLine());
35     }
36     
37     public static void doSL() throws Exception{
38         double totalSLScore = 0.0;
39         for(int i = 0; i < numSLCourses; i++){
40             System.out.println("What is the score of your next HL course?");
41             double nextScore = Double.parseDouble(br.readLine());
42             totalSLScore += nextScore;
43         }
44         avgSLScore = totalSLScore/numSLCourses;
45     }
46     public static void doHL() throws Exception{
47         double totalHLScore = 0.0;
48         for(int i = 0; i < numHLCourses; i++){
49             System.out.println("What is the score of your next HL course?");
50             double nextScore = Double.parseDouble(br.readLine());
51             totalHLScore += nextScore;
52         }
53         avgHLScore = totalHLScore/numHLCourses;
54     }
55     
56     public static void finalCalcuationsAndResults(){
57         if(avgHLScore > avgSLScore){
58             System.out.println("Which means you scored on average better for HL.");
59         }
60         else if(avgSLScore > avgHLScore){
61             System.out.println("Which means you scored on average better for SL.");
62         }
63         else{
64             System.out.println("You scored equally well on HL and SL courses.");
65         }
66         System.out.println("Your average HL score is " + avgHLScore);
67         System.out.println("And your average SL score is " + avgSLScore);
68         
69     }
70 }
71