CS302 Sample Questions for Exam #1

Part I : True or False

1. T A java compiler changes Java source code into Java bytecodes.
2. T Compilation errors include mistakes in syntax.
3. T The data type MainWindow is a reference data type.
4. T During the analysis phase of software development, the program's requirements are specified.
5. T Math.PI accesses the class constant PI in the Math class.
6. T Instance methods are declared without the static modifier.
7. T Visibility modifiers control access to the members of a class.
8. T Arguments are passed to a method using the pass-by-value scheme.
9. T Nesting is when a statement is placed inside the body of another statement.
10. T Execution always begins in the main method for all Java applications.
11. T Comments are intended for programmers.
12. T 5.5 is an example of a literal constant.
13. T x = y; means x is assigned the value in y.
14. T Local variables only exists while their method executes.
15. T The data type double is a primitive data type.
16. F i = o.setMax(22) public int setmax(int m)
17. F o.setData(d, 11.22) public void setData(double f,int n)
18. F new TestObject(d,i) public TestObject(double di)
19. F o.showValues() private void showValues()
20. F o.find(j,i,d) public void find(double d,int i,int j)

    Part II: Multiple Choice

21. A an if statement with a while loop nested inside
22. E how the methods are implemented
23. E

    if(i == 10 || i == 15) d = 2.2;
    else if(i == 25) d = 7.7;
    else d = 1.1;
    

24. E

    int n = 5, factorial = 1;
    do {
      factorial = factorial * n;
      n = n + 1;
    } while (n > 0);
    

25. C !coke && !pepsi
26. C fragment 1 and fragment 3 only
27. A i only
28. D 7
29. B All instances have the same values for instance variables age and weight.
30. B 0.5

Part III: Written Answers

1. Output of the code fragment:
   

   --
   ***
   ----
   *****
   ------
   

2. The code for instantial class Bus.
   

   class Bus {
   
      private int maxCapacity; //maximum number of people on bus (pos. int)
      private int currentNum;  //number of people currently on bus (pos. int)
      private int totalPassengers; //total number of people ever on bus (pos. int)
      private double ticketPrice;  //amount people pay to get on bus (pos. double)
   
      /**
       * Constructor: sets currentNum and totalPassengers to 0. 
       * @param m sets the maxCapacity 
       * @param price sets the ticketPrice
       * Bugs: Does no error checking on parameters
       **/
       public Bus(int m, double price){
         totalPassengers = 0;
         currentNum = 0;
         ticketPrice = price;
         maxCapacity = m;
       }
   
   
       /**
        * calcIncome returns the income generated by all people who ever got
        * on this bus
        * @param none
        * @return totalPassengers * ticketPrice
        **/
        public double calcIncome(){
           return totalPassengers * ticketPrice;
        }
   
   
        /**
         * addPassengers returns error code if parameter is negative, otherwise
         * adds upto the capacity number of people wanting on this bus. If this 
         * would have exceeded the capacity, then return how many extra, else
         *  return 0
         * @param people number of people wanting on this bus
         * @return -1 is error, 0 is all fit, pos int is overflow
         **/
        public int addPassengers(int people){
          if(people < 0)
             return -1;
          //If we add people to bus, how much does that exceed capacity?
          int overflow = currentNum + people - maxCapacity; 
   
          if(overflow > 0) { //people is too much!
             totalPassengers += people - overflow;  //add only those who fit
             currentNum = maxCapacity;              //set to max
             return overflow;
          } else { //just add people
             currentNum += people;
             totalPassengers += people;
             return 0;
          }
       }
    
       /**
        * removePassengers returns -1 if parameter is negative, otherwise
        * removes at most all the current passengers. If people is more than 
        * the current number, then remove all and return 1. Otherwise, remove
        * requested number and return 0.
        * @param people number of people who wish to get off bus
        * @return -1 is error, 1 is underflow, 0 is OK
        **/
        public int removePassengers(int people){
          if(people < 0) 
             return -1;
          if(people > currentNum) { //people is too much!
             currentNum = 0;
             return 1;        //underflow value
          } else {            //just remove people
             currentNum -= people;
             return 0;
          }
        }
   
   }
   

3. Write a code fragment:
   

   Bus busOne = new Bus(40, .5);
   Bus busTwo = new Bus(15, .75);
   
   busOne.addPassengers(22);
   busTwo.addPassengers(22);
   
   //Assume we know that busOne has more passengers
   out.printLine("The income is $" + busOne.calcIncome());