Test 1 Solutions and Grades

Below is our first test, along with the answers.

1. (10%) The following program fails to compile. Why does it fail to compile?
   

   public class BrokenA {
     public static final double RATE = 0.5;
   
     public static void main(String[] args) {
       double x = 0;
       x = 10 * RATE;
       RATE = 20;
     }
   }

   Answer: Because we are trying to re-set the value of RATE which is a final variable.
   
   
   
2. (40%) What does the program below print when it runs?
   

   import java.util.Scanner;
   
   public class Mystery {
   
     public static void main(String[] args) {
       String sentence = "A rebel without a clue";
       for (int i = 0; i < sentence.length(); i++){
         char c = sentence.charAt(i);
         int r = 0;
         for (int j = 0; j < sentence.length(); j++){
           if (sentence.charAt(j) == c)
             r++;
         }
         System.out.println(c + ":" + r);
       }
     }
   
   }

   Answer:
   

   A:1
    :4
   r:1
   e:3
   b:1
   e:3
   l:2
    :4
   w:1
   i:1
   t:2
   h:1
   o:1
   u:2
   t:2
    :4
   a:1
    :4
   c:1
   l:2
   u:2
   e:3
   

   
   
3. (50%) Write a program that:
   
   1. Asks the user to enter any number of words. If the user enters the word done then the program ends. You can assume the user will always enter a word (he will not type in spaces, numbers, etc.)
   2. After the user enters each word you will print out a score such that:
      
      1. If a word has 9 or fewer letters the score is 2 times the number of letters.
      2. If a word has 10 or more letters the score is 10 plus 2 times the number of letters.
      3. If a word starts with the letter 'z' then it gets a score of 500, regardless of how many letters it has.
      4. After the user enters done, you print out the longest word.
      
      
   Below is a sample session:
   

   Enter word:hello
   Score=10
   Enter word:howareyouthere
   Score=38
   Enter word:a
   Score=2
   Enter word:z
   Score=500
   Enter word:zoologically
   Score=500
   Enter word:done
   The longest word was howareyouthere
   

   Answer:
   

   import java.util.Scanner;
   
   public class WordChecker {
   
     public static void main(String[] args) {
       Scanner keyboard = new Scanner(System.in);
       String longest = "";
       while  (true){
         System.out.print("Enter word:");
         String word = keyboard.next();
         if (word.equalsIgnoreCase("done"))
           break;
         System.out.print("Score=");
         if (word.substring(0,1).equalsIgnoreCase("z"))
           System.out.println(500);
         else if (word.length() > 10)
           System.out.println(10 + 2*word.length());
         else
           System.out.println(2*word.length());
         if (word.length() > longest.length())
           longest = word;
       }
       System.out.println("The longest word was " + longest);
     }
   }

   
   

Below is the grade distribution for this test. The zeros are people who did not take the test. I will be handing back the tests on our next class.