Introduction to Programming

1. Introduction to Programming Java Lab 6: if Statement JavaLab6 lecture slides.ppt Ping Brennan (Ping.Brennan@gmail.com) 14 February 2014

2. Java Project Project Name: JavaLab6 QuizGrading LeapYear

3. Class QuizGrading • Reads in an integer (from the keyboard) as the score. • Displays the grade assigned to the score according to the following table: • Objectives • Understand the use of multiple if statements (if-elsestatements). • Applying relational operators: <, <=, >=

4. Class QuizGrading (2) • Method • Applying • Read a numeric input (i.e. score) from the keyboard. • char grade = ' '; // Java type char • if (score >= 90) • { grade = 'A'; } • else if (score >= 80) • { grade = 'B'; } • else if/*To Do – write similar if–else statements to check the score • for grades ‘C’, ‘D’ and ‘E’. */

5. Anatomy of Class QuizGrading import java.util.Scanner; public class QuizGrading { public static void main(String[] args) { /* To Do - write code to read score from the keyboard which is an integer of type int. */ char grade = ''; if (score >= 90) { grade = 'A'; } else if (score >= 80) { grade = 'B'; } else if // To Do - write similar Java if-else statements // Lastly, print the grade, along with an appropriate description } }

6. Class LeapYear • Reads in a year and computes whether the year is a leap year. • Objectives • Understand the use of if-else statement • Applying the arithmetic operator %(computes the remainder of an integer division) • Using relational operators: ==, != • Using boolean operators: && , ||

7. Class LeapYear (2) • Formulae • Applying • Read year input from keyboard using Scanner class • Dry-run of leap year algorithm if a year is divisible by 4 but not by 100, it is a leap year. if a year is divisible by 4 and by 100, it is not a leap year unless it is also divisible by 400. boolean a = (year % 4) == 0; // divisible by 4 boolean b = (year % 100) != 0; // not by 100 boolean c = ( (year % 100) == 0 ) // divisible by 100 && ( (year % 400) == 0 ); //and divisible by 400 Use the boolean expression:( a && ( b || c) )to find a leap year.

8. Anatomy of Class LeapYear import java.util.Scanner; public class LeapYear { public static void main(String[] args) { /* To Do: (i) declare a variable year of type int (ii) read a numeric input (year) from the keyboard */ /* declare the boolean variables a, b and c as shown in slide 7 */ /* write an if-else statement and use the boolean expression shown in slide 7 */ /* write a println statement to display the result of the computation. */ } }

9. Flow Chart for if-else statement[back to slide 4] Enter score: 95 start Enter score: 83 score >= 90 true false Enter score: 79 score >= 80 grade = ‘A’ true false Enter score: 60 grade = ‘B’ true score >= 70 false grade = ‘C’ more if-else statements Print statement

10. Dry-run of LeapYear algorithm Back to Slide 7

11. Dry-run of LeapYear algorithm (solution) Back to Slide 7