1. Crash course in the Java Programming Language

2. Hello World in Java
import java.util.*; /** A class for producing simple greetings. */ public class Greeter { private String name; Constructs a Greeter object that can greet a person or aName the name of the person or entity who should be addressed in the greetings. public Greeter(String aName) name = aName; } Greet with a "Hello" a message containing "Hello" and the name of the greeted person or entity. public String sayHello() return "Hello, " + name + "!";

3. Hello World Tester
import java.io.*; import java.util.*; public class GreeterTester { public static void main(String[] args) Greeter worldGreeter = new Greeter("World"); String greeting = worldGreeter.sayHello(); System.out.println(greeting); }

4. Identifiers (names) Java is case sensitive
Identifiers can begin with an underscore or letter and contain only letters, underscores, or numbers
We choose identifiers for variables, classes, methods, and packages

5. Identifiers variables must start with a letter or underscore
consists of letters, digits & underscores
cannot be a reserved word
cannot be true, false, or null
firstScore score1 Score
3scores score-1 myScore
Capitalize “middle” words
Usually start variables with lowercase,
classes with uppercase – class name and file name must be identical.
Java is case sensitive!!!!
Score score

6. Primitive Data Types Integer data types: int byte short long
Floating-point types:
double
float
Character type:
char
Logical Type:
boolean

7. Primitive Types

8. Declaring Variables Syntax: Examples: int num1; double num2, num3;
type identifier1, identifier2, … ;
Examples:
int num1;
double num2, num3;
double num4;
We must declare a variable before it can be used!

9. Assignment Statement Syntax: variable = expression;
expression is evaluated and then the value of expression is stored in variable.
We should initialize our variables.
int num1 = 0;
double num2 = 0.0, num3 = 0.0;
Incorrect: int 0 = num1;
In Java, 0 is treated as an integer while 0.0 is treated as a floating-point number.
We may assign a value to a variable more than once. However, a variable can only retain its most recently assigned value.

10. Operators and Precedence
( )
/ * %
prefix
postfix
< > <= >=
== !=
&& ||
= += -= /= *=

11. Literals is a constant value that appears directly in a program.
Character Data Type: represent a single character
//initialize a character data type named “firstLetter” with value ‘A’
char firstLetter = 'A';
A character literal is enclosed in single quotation marks. Which of the following is a character literal?
‘a’ ‘A’ ‘ ‘ ‘$’ ‘7’
‘ab’ ‘ a ‘ “a”
A string literal must be enclosed in double quotation marks.
The String type
String a = “Chapter”;
String b = “Chapter” + 2;
(note: please ignore the smart quotes )

12. Standard I/O
import java.util.*; ... System.out.print( ); System.out.println() // must declare a scanner object for input Scanner keyboard=new (System.in); someInt = keyboard.nextInt(); somestr = keyboard.next(); someReal= keyboard.nextDouble();

13. Formatting Output import java.text.*; DecimalFormat moneyStyle =
new DecimalFormat("$0.00");
double amount = 4.56;
System.out.println(moneyStyle.format(amount));
======================================================
DecimalFormat fiveDecimals = new DecimalFormat(" ");
const double PI = ;
System.out.println(fiveDecimals.format(PI));

14. If Statement
Syntax:
if (BooleanExpression)
Single Java Statement;
where Statement is any Java statement including a block {}.
Semantics:
If BooleanExpression is true,
then execute the Single Java Statement.
(Otherwise, skip the Statement.)

15. Lab Time: Files and Exceptions Exercise: Work along with me.
On your USB drive: Create a NetBeans Projects directory
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