1. Primitive Types Operators Basic input and output
Introduction to Java
Primitive Types
Operators
Basic input and output

2. Basic Output For console output, there are 2 basic commands:
System.out.print( <Your text goes here> );
Prints text and leaves cursor on same line
System.out.println(<Your text goes here> );
Prints text and moves cursor to start of next line

3. Your first program
The traditional first program in computer science is the hello world program
We will complete this together to try your first basic output to the screen.
Source Code:
public static void main( String[] args ) {
System.out.println( “Hello World” ); }
Every statement in Java ends with a “;”

4. Escape Characters How do you print a “ character in Java?
System.out.print( “ );
System.out.print( “”” );
Try them and see what Java has to say
How would you tell Java to move to a new line or tab forward?
To address this issue, Java uses the backslash as an “escape character”
It indicates to Java that when it sees the “\” it has to do something special, and not just print what it sees.

5. There are others, but we’ll stick to these
Escape Characters
Character Sequence
Description \”
Quote \n
New Line \t
Tab \\
Backslash
There are others, but we’ll stick to these

6. Working with escape characters
What is printed:
System.out.println(“\”\\\n\\\”/\\/n\t/t”);
System.out.println( “\”\\n\n\\t\t\””);
What code will print:
“\n//\\\t
\””
“\n\\/t\\”
\n ””

7. String Concatenation You’ll notice a vertical line in your source code
This represents a standard page width for printing
You can write past the line, but when you print your work it will not fit on the paper
One thing you can do is tell java to join two strings together using the “+” operator
This is known as String concatenation

8. String Concatenation Example
System.out.println( “Oh Canada,
Our home and native land…” );
Error, string missing quotation
Fix it as follows:
System.out.println( “Oh Canada,” +
“Our home and native land…” );
Prints: Oh Canada, Our home and native land…
To make it print on multiple lines, we have a couple of choices:
System.out.println( “Oh Canada” );
System.out.println( “Our home and native land…” ); OR
System.out.println( “Oh Canada,\n” +

9. Basic Output Exercises
Choose a poem or song to print on the console with Java
Using only 1 System.out.println command (and the + and \n operators) make a “letter head” with your name and address:
Ex.
Johnston Heights
Avenue
Surrey, BC
V3R 0R9
Telephone:  

10. Escape Character Exercises
Write a program that displays the following:
“\n\\n\”\t”
\\tt\n\\”
Write a program that displays student information for 4 of your class mates in a table using the \t and \n characters Ex
Name Age Favorite Sport
John 16 Soccer
Jane 17 Hockey

11. Primitive Data Types Name Description Example int Integer
int age = 17;
double
Floating point (decimal) number
double radius = 1.23;
boolean
Stores the value True or False
boolean stop = true;

12. Basic Math Operators Operator Description * Multiplication / Division+
Addition -
Subtraction %
Remainder (Mod)

13. Precedence
Math operators in Java have the same precedence as general Mathematics
6 + 7 * 3 = 27
Brackets can also be used to change the order of operations
(6+7) * 3 = 39

14. Shortcut Operators
Some tasks are common enough that there are shortcuts for them
Operator
Example
Equivalent to
++ (increment)
x++
x = x + 1
-- (decrement)
x--
x = x - 1 +=
x += 5
x = x + 5 -=
x -= 3
x = x – 3 /=
x /= 2
x = x/2 *=
x *= 6
x = x * 6 %=
x %= 7
x = x %7

15. Integer Division
Java treats division between integers different than your calculator
For example, your calculator would tell you that 10 / 4 = 2.5
Java would tell you that 10/4 = 2
This is because integers do not have a decimal place, so it is thrown away
Examples:
6 / 4 = 1
7 / 2 = 3
10 / 11 = 0
16 / 4 = 4

16. Modulus or Remainder So how do you get the missing decimal place back?
The % operator gets the remainder that was thrown away when the integers were divided
For example:
10 / 3 is 3 Remainder 1, so 10 % 3 = 1
15 / 5 is 3 Remainder 0, so 15 % 5 = 0
18 / 4 is 4 Remainder 2, so 18 % 4 = 2
There are surprisingly a lot of application of the % operator that we will use later on in the course

17. String Concatenation With Numbers
Sometimes you want to print text with numbers and there is an important rule in Java to be aware of:
When you use the + operator, if one of the operands is a string, then both will be treated as a string
+ only performs addition if BOTH operands are numbers
This can make for some peculiar output

18. String Concatenation With Numbers
Concatenation occurs from left to right
What is printed?
System.out.println( “Sum is: “ );
Prints: “Sum is 123”
System.out.println( “Sum is: “ + (1+2+3) );
Prints “Sum is 6”
System.out.println( 1 + “2” (4 + 5) );
Prints 1239
As a general rule, put your arithmetic operations in brackets so they are done separately from the string concatenation

19. Math Operator Exercises
Case Study: Multiplication table
Together, we’ll program java to display a multiplication table for us.
The first time we do this we won’t use a variable
The second time we’ll compare how a variable makes our program more versatile

20. Constants in Java
As a programmer you’ll run in to constant values like often
In order to guarantee the value is not changed somewhere in your code, you can use the final keyword to indicate to java that the value is not to change
Example:
final double MILES_PER_KM = 1.6;
Note the style to indicate a constant is to capitalize the variable name

21. Basic Input
Interaction through the keyboard is done with the Scanner class.
It is part of the standard Java library that comes with the compiler.
In order to use it, we have to tell Java we want to add it to our program
import java.util.Scanner;

22. Basic input
First we have to tell Java where we want to scan, for our class it will always be System.in
Create the Scanner as follows:
Scanner keyboard = new Scanner( System.in );
It can have any name, it does not have to be called keyboard (it is a variable)
The new keyword in Java tells java to create a new Object for us to use
Objects perform tasks for us, to access these tasks we have to use the “.” operator
Our compiler has this built in as a feature, when you type: “keyboard.” and wait, a list a methods pops up

23. Scanner Methods The most common methods we’ll use for Scanners are:
next()  gets the next word (separated by space)
nextLine()  gets the next line of text
nextDouble()  gets data as a double
nextInt()  gets data as an integer
When you read data from the keyboard with these methods, the enter key invokes them to start

24. Our first program with input
Together we’ll create a program that produces the following interactions:
What is your name? Joe
How many toonies are in your wallet? 5
How many loonies are in your wallet? 3
How many quarters are in your wallet? 6
How many dimes are in your wallet? 7
How many nickels are in your wallet? 2
How many pennies are in your wallet? 4
Joe, You have $15.34

25. Math Operator Exercises
Create a program for each conversion:
Celsius to Fahrenheit
Pounds to kilograms
inches to centimeters
Create a program for each formula:
Compute the area of a circle
Compute the volume of a Sphere
Computer the surface area of a Cylinder
You can find the formulas on the internet or in your agendas
Use constants and variables where appropriate.
Create a program to determine the number of vehicles needed for a trip:
How many people are going on the trip? 27
How many seats does each vehicle have? 5
You will need 6 vehicles. 5 will be full and the 6th will have only 2 people (3 empty seats).
Complete the setTime method in the AnalogClock class

26. Interactive Programming Exercises
Create a simple store front that displays a welcome screen and a menu. Prompt the person for how many of each item they want and create a bill for them:
|**************************************************|
| JOE’S JAVA JOINT |
Coffee – $1.50
Espresso - $2.50
Latte - $3.25
Tea - $1.75
How many coffees do you want? 2
How many espresso do you want? 4
How many lattes do you want? 0
How many teas would you like? 1
Sub Total: $14.75
Taxes (12%): $1.77
Total: $16.52
Thank you, come again!

27. Data Conversions What gets printed? Rules for math operators:
System.out.println(10 / 4.0 );
System.out.println( );
System.out.println( );
System.out.println( * 4.0 );
Rules for math operators:
If BOTH operands are integers, then integer math is performed
Otherwise, floating point arithmetic is used

28. Data Conversions What happens if you try this in main?
int result = 10 / 4.0;
double result = 10 / 4;
double result = 10 % 3;
int result = 10 % 4.0;

29. Casting Rules
If the conversion will lose data, Java will give an error
Going from 13.5 (double) to and int would lose information when 13.5 would become 13
There is no problem however if you want to store 13 (int) into a double value because nothing is lost by 13.0
The way you tell Java you’re aware of the error and that it’s OK to compile is by casting
Casting changes the data type

30. Casting Examples int i1 = 12; int i2 = 4; int i3 = 6;
double d1 = 24.0;
double d2 = 3.0;
double d3 = 2.0;
double d4 = 2.5;
System.out.println( i1 / (int)d2 );

31. Casting Examples int i1 = 12; int i2 = 4; int i3 = 6;
double d1 = 24.0;
double d2 = 3.0;
double d3 = 2.0;
double d4 = 2.5;
System.out.println( d2 / (double)i2 );

32. Casting Examples int i1 = 12; int i2 = 4; int i3 = 6;
double d1 = 24.0;
double d2 = 3.0;
double d3 = 2.0;
double d4 = 2.5;
System.out.println( d2 / (int)d4) );

33. Casting Examples int i1 = 12; int i2 = 4; int i3 = 6;
double d1 = 24.0;
double d2 = 3.0;
double d3 = 2.0;
double d4 = 2.5;
System.out.println( (int)(d1 / d4) );

34. Casting Examples int i1 = 12; int i2 = 4; int i3 = 6;
double d1 = 24.0;
double d2 = 3.0;
double d3 = 2.0;
double d4 = 2.5;
System.out.println( (double)(i1 / (int)d4) );

35. Casting Examples int i1 = 12; int i2 = 4; int i3 = 6;
double d1 = 24.0;
double d2 = 3.0;
double d3 = 2.0;
double d4 = 2.5;
System.out.println( (double)i2 / i3 );

36. Casting exercises

37. Casting Exercises Cont’