Unit Conversion Calculator: Mile to Kilometer and Fahrenheit to Celsius

1. Lecture 9

2. Today’s topic • Let’s continue to do exercise (Lecture 8) • Character data type • Char • String class • String

3. Exercise 1 • Mile to Kilometer conversion 1 Mile is 1.6 Kilometer Create a calculator application to convert unit from Mile to Kilometer - Ask an user to enter one number in mile - Calculate the unit conversion - Print out the result in Kilometer for the user.

4. public class MyCalculator { static final double MileToKilometer = 1.6; public static void main(String[] argv) { JFrame frame = new JFrame(“My Calculator"); IOConsole console = new IOConsole(); frame.getContentPane().add(BorderLayout.CENTER, console); frame.setSize(500, 300); frame.setVisible(true); console.println( "This program converts mile to kilometer.” ); double mile = console.readDouble( “Enter number in mile: “ ); double kilo = MileToKilometer * mile; console.println( mile + “ mile is " + kilo + “ kilometer"); } }

5. Exercise 2 (comment out previous one) • Fahrenheit Tf to Celsius Tc conversion Conversion formula Tc = (5 / 9) * (Tf – 32) Create a calculator application to convert unit from degree Fahrenheit to Celsius - Ask an user to enter number in Tf - Calculate the unit conversion - Print out the result in Tc for the user.

6. public class MyCalculator { public static void main(String[] argv) { JFrame frame = new JFrame(“My Calculator"); IOConsole console = new IOConsole(); frame.getContentPane().add(BorderLayout.CENTER, console); frame.setSize(500, 300); frame.setVisible(true); console.println( "This program converts F degree to C degree.” ); double Tf = console.readDouble( “Enter degree in F: “ ); double Tc = (5.0/9.0) * (Tf – 32); console.println( Tf + “ F degree is " + Tc + “ C degree"); } }

7. Extra methods in IOConsole setForeground( Color ) where Color will be one of colors such as Color.Red, Color.Blue, Color.Green, etc. (page 43) setFont( Font ) where Font will be Font object as follow (page 42) Font font = new Font( family, style, size); family: “Serif”, “SansSerif”, “Monospaced”, etc style: Font.PLAIN, Font.BOLD, Font.ITALIC size: integer

8. Extra methods in JFrame setLocation( int x, int y ) move a window to (x, y) position of the screen

9. public class MyCalculator { public static void main(String[] argv) { JFrame frame = new JFrame(“My Calculator"); IOConsole console = new IOConsole(); Font font = new Font( “Serif”, Font.ITALIC, 20); console.setFont( font ); console.setColor( Color.GREEN ); frame.getContentPane().add(BorderLayout.CENTER, console); frame.setLocation(200,300); frame.setSize(500, 300); frame.setVisible(true);

10. Challenge • If you want to do calculation twice or more without closing windows, then you can use loop to ask users for entering new numbers. console.println( "This program adds two numbers.” ); for( int i=0; i<5; i++) { console.println( "This program converts F degree to C degree.” ); double Tf = console.readDouble( “Enter degree in F: “ ); double Tc = (5.0/9.0) * (Tf – 32); console.println( Tf + “ F degree is " + Tc + “ C degree"); }

11. Exercise 3 (comment out previous one) • Circle circumference and area PI = 3.14 circumference = 2 * PI * radius area = PI * (radius)2 radius • Let’s create a new class, named MyCircle • So, the file name should be MyCircle.java • MyCircle is an application to calculate the circumference and area of the circle, whose radius is provided by users

12. Exercise 3 (start with this) /* File name: MyCircle.java by Chonho Lee -------------------------- This program calculates the circumference and area of circle */ import acm.io.*; import java.awt.*; import javax.swing.*; public class MyCircle { } Comment Import packages

13. Today’s topic • Character data type • Char • String class • String

14. Character • Character is one of primitive data types of variable (such as integer and double) • Character variable contains one character as its value • Alphabet: a, b, c,…,A, B, C,… • Digit: 0, 1, 2, … • Symbol: +, -, =, !, <, >, $, %, …

15. Declaration of Character Variable We use keyword char Similar to integer and double char ch = ‘b’; Singlequotation mark Data type Variable name Value

16. Examples of char variable char grade = ‘B’; char plus = ‘+’; char num5 = ‘5’; System.out.println( “My grade is “ + grade ); System.out.println( “My grade is “ + grade + plus); System.out.println( num5 + plus + num5 + “ is 10“ ); On the screen, you will see My grade is B My grade is B+ 5+5 is 10

17. Strings • String is basically just a collection of characters. • Thus, the string “O’Bryant” could be thought of as a sequence of 8-elements ('O', '’', ‘B', 'r', ‘y', ‘a‘, ‘n’, ‘t’).

18. Strings in java Capital ! • String is a class in Java • Strings are constant (values cannot be changed once they are created) • Set of characters “Chonho Lee" is a string. • "A" is a string, 'A' is a character. Note:Characters are delimited by single quotes and Strings are delimited by double quotes.

19. Declaration Declare variable int val = 10; val 10 Since String is a classCreate object! (declare object) String name = new String(“Chonho”); String class name Simplify! Chonho String name = “Chonho”;

20. Examples of String String name = “Chonho”; String job = “Student at UMB”; String id = “4816828”; String email = “chonho@gmail.com” System.out.println( name + “ information” ); System.out.println( “Who? “ + job + “, ID: “ + id ); System.out.println( “Please email at “ + email ); On the screen, you will see Chonho information Who? Student at UMB, ID: 4816828 Please email at chonho@gmail.com

21. Today’s Exercise • Name card creator • Let’s create a name card by name card creator application • Write a class, named MyNameCard • Ask an user to enter first name • Ask an user to enter last name • Ask an user to enter age • Print out the results

22. public class MyNameCard { public static void main(String[] argv) { JFrame frame = new JFrame(“My Calculator"); IOConsole console = new IOConsole(); frame.getContentPane().add(BorderLayout.CENTER, console); frame.setSize(500, 300); frame.setVisible(true); console.println( "This program create a name card for users” ); String first = console.readLine( “Enter first name: “ ); String last = console.readLine( “Enter last name: “ ); String age = console.readLine( “Enter your age: “ ); console.println( “Hi, my name is “ + first + “ “ + last ); console.println( “I am “ + age + “ years old” ); } }