1. Introduction to Programming Java Lab 3: Variables and Number types 25 January 2013 1 JavaLab3.ppt Ping Brennan (p.brennan@dcs.bbk.ac.uk)

2. Java Project Project Name: JavaLab3 2 ExerciseWithIntegers OrderPrice SeparateDigits

3. Class ExerciseWithIntegers Objectives –Perform integer calculations using the arithmetic operators and Math methods. –Understanding integer as a data type. Computation Math.abs(x), Math.min(a, b), Math.max(a, b) where x, a, b, are integers (or expressions) of type int. Data type integer range -2 31 to 2 31 -1 i.e. -2147 483648... 2147483647 Applying –Read keyboard input using Scanner class 3 +, –, *, /,

4. Anatomy of Class ExerciseWithIntegers import java.util.Scanner; // first line in the program public class ExerciseWithIntegers { public static void main(String[] args) { // create a Scanner object in to read keyboard input Scanner in = new Scanner(System.in); System.out.print("Enter two integers: "); // prompt user to input int num1 = in.nextInt(); // reads in first integer input /* Write code similar to the above statement to declare a new variable num2 of type int to read in the second integer input. */ /* Next write separate Java statements to print: the sum, the difference, the product, the average, the absolute value of the difference, the maximum and the minimum. */ } Hint: use the methods Math.abs(x), Math.min(a,b) and Math.max(a,b). 4

5. Class OrderPrice Calculates the price of an order from the total price and number of books ordered. Objectives –Using arithmetic operators : +, –, *, / –Understanding arithmetic expressions Formulae Applying –Read keyboard input using Scanner class –Declaring variables of data types: int and double 5 tax = totalBookPrice * 0.075; shippingCharge = noOfBooks * 2.00; orderPrice = totalBookPrice + tax + shippingCharge ;

6. Anatomy of Class OrderPrice import java.util.Scanner; // first line in the program public class OrderPrice { public static void main(String[] args) { // Write separate Java statements to do the following: // a) Read in the total book price and the number of books // b) Compute the tax (i.e. 7.5% of the total book price) // c) Compute the shipping charge ($2 per book) // d) Price of order = total book price + tax + shipping charge // e) Print the price of the order } 6

7. Class SeparateDigits Reads in a five digit positive integer and prints out the individual digits, separated by spaces. For example, the input 16348 is printed out as: 1 6 3 4 8 Objective –Understand the arithmetic operators: % (modulus) and / (division). Formulae Applying –Read input using Scanner class 7 tenThousand = posNumber /10000; thousand = ( posNumber % 10000) / 1000; hundred = ( posNumber % 1000) / 100; // continue to write own formulae to calculate ten and unit

8. Anatomy of Class SeparateDigits import java.util.Scanner; // first line in the program public class SeparateDigits { public static void main(String[] args) { /* Declare a variable posNumber of type int and store a five digit positive number input in the variable. */ // firstly declare all relevant variables below before using them. tenThousand = posNumber /10000; thousand = ( posNumber % 10000) / 1000; hundred = ( posNumber % 1000) / 100; // write Java statements to calculate ten and unit // write code to print out the individual digits, separated by spaces } 8