1. Look carefully at the program shown below and answer the questions that follow.

Transcription

1 1. Look carefully at the program shown below and answer the questions that follow. a. What is the name of the class of this program? BillClass b. Identify one variable that holds a String. item c. What data type is variable quantity declared? int (of type integer) d. In which line is a constant variable declared? Line 6 e. To what value is the constant variable initiated? 18 f. Identify one line which outputs a prompt. Line 8/10/12/18/21/24 g. Why is VAT declared as a constant and what is the advantage of doing this? VAT still holds a place in memory just like a variable. However, the value of constants do not change during program execution and we want the value of VAT to remain the same. ADV: if the VAT value changes, you just need to 1 Margaret Bajada (2017) replace it with the new value once. 1 Margaret Bajada (2017)

2 h. Which line is outputting the cost of the items bought including the VAT? Line 24 i. What is the difference between the + shown in line 21 and the + in line 23? The + in line 21 - concatenation of strings The + in line 23 - performs addition j. Identify one line in which automatic type conversion is taking place. Line 20 k. Write down the lines where input from the user is requested. Lines 9, 11, 13 l. Write down the statement that prints a blank line. System.out.println(); m. What is the difference between Keyboard.readString(), Keyboard.readInt() and Keyboard.readDouble()? Keyboard.readString(); - accepts a String from the user. Keyboard.readInt(); - accepts an integer from the user. Keyboard.readDouble(); - accepts a number of type double from the user. n. Which is the class and which is the method in Keyboard.readString()? Class: Keyboard Method: readstring() o. How do we distinguish between a class and a method? Class: Starts with an uppercase letter. Method: Starts with a lowercase letter and includes parentheses at the end (). p. Write down all the classes and the methods that you see in the program. Classes: BillClass, String, System, Keyboard Methods: readstring(), readint(), readdouble(), println() 2 Margaret Bajada (2017) 2 Margaret Bajada (2017)

3 2. Create a class named SimpleCalc where the user is asked to enter two integers. You then need to output their: addition, subtraction, multiplication (using *) and division (using /). 3 Margaret Bajada (2017) 3 Margaret Bajada (2017)

4 3. Create a class named NumAvg where the user is asked to enter three numbers of type double and output their average. 4 Margaret Bajada (2017) 4 Margaret Bajada (2017)

5 4. Create a class named Rectangle where the user is asked to enter the length and breadth of a rectangle. You are then to calculate and print the perimeter and area of the rectangle. 5 Margaret Bajada (2017) 5 Margaret Bajada (2017)

6 5. Create a class named VolCuboid where the user is asked to input the length, breadth and height of a cuboid. You are then to calculate and output the volume of the cuboid. 6 Margaret Bajada (2017) 6 Margaret Bajada (2017)

7 6. Create a class named CircleArea where the user is asked to enter the radius for a circle. You are then to calculate and output the area for the circle. NOTE: take the value of PI as a constant whose value is Margaret Bajada (2017) 7 Margaret Bajada (2017)

8 7. Create a class named MyParticulars where you ask a user to enter his/her name, surname, and three examination marks. You are then to output back the particulars of the student together with the average of the examination marks. 8 Margaret Bajada (2017) 8 Margaret Bajada (2017)

9 8. Create a class named SphereVol where the user is asked to enter the radius of a sphere. You are then to calculate and output the volume of the sphere. NOTE: V = 4/3 x PI x r 3 9 Margaret Bajada (2017) 9 Margaret Bajada (2017)

10 9. Create a class named CylinderTSA where the user is asked to enter the radius and height for a cylinder. You are then to calculate and output the total surface area for the cylinder. NOTE: TSA = (2 x PI x r 2 ) + (2 x PI x h) 10 Margaret Bajada (2017) 10 Margaret Bajada (2017)

11 10. Create a class named ConversionCtoF where the user enters a temperature in degrees Celsius and then you convert and print the temperature in Fahrenheit using the following formula: F = (1.8 x C) Margaret Bajada (2017) 11 Margaret Bajada (2017)

12 11. Find the syntax errors in the following programs and suggest a solution to solve the errors. Error/s: Variables length and breadth and area were not declared to int. Declare variables at the beginning of the program. int length, breadth, area Solution: Keyboard.readInt() were not corresponded to any variable. Error/s: length = Keyboard.readInt(); breadth = Keyboard.readInt(); Solution: breadth is an int so it should be assigned to the readint() method. Error/s: Keyboard is a class so it should start with an uppercase letter. Solution: breadth = Keyboard.readInt(); 12 Margaret Bajada (2017) 12 Margaret Bajada (2017)