Java file = All of our code

.md file = Text, definitions, etc;

Intro to Java

A Java program can be characterized as an object represented in a class

Currently our program has a Main Object, Inside of this object we have the Main class.

Output

In Java to output an item to the console we use: 'System.out.print()' and System.out.printLn()' System.out.println() prints the statement and moves to the next line, while System.out.print() just prints the statement.

Comments

A comment is used as user annotation with the purpose of being human readable

Line Comments follow double backslashes. //

Block Comments are contained within /* Comments*/

Identifiers

In Java use the term identifier to describe a variable, parameter, constant, user-defined method or user-defined class

• Cannot begin with digit
• Can only contain letters, digit, and underscores
• Case-sensitive age != Age

*Note: * -class name starts with a capital letter -reserved words are entierely lowercase and may not be used as identifiers(Reserved words will show up in blue)

Types

Primitive or built-in types in Java are

• int An integer
• boolean True or False (boolean shirtColor = true)
• double floating-point number (2.73)
• char single character

*Note: * Integers have a fixed amount of memory, so there is a limit to how many digits you can store(2^31 -1)

Variables

Variables are a type of identifier that stores a value of a specific type

we can create variables using declaration

• int age;
• double x, y;
• boolean found;
• char letter;

We can also intialize a variable in its declaration

• int count = 1;
• x = 2.0
• char c = '8':

Chars

[ASCII CHART] (https://scratch.mit.edu/projects/578101866/editor/)

Each character is associated with an ASCII value.

#Type cast

one type can be cast to another compatible type if appropriate

char letter = c'c';

int total, n;
double average;
average = (double)total/n //total cast to double to ensure real division is used

Note : Cast a floating-point number to an integer simply rounds the number down

Final Variable

A final variable or user-defined constant, identified by the keyword final, is a quantity whose value will not change

final double TAX_RATE = 0.08;

• Constant identifiers are, by convention, capitalized
• final variable can be declared with initializing immediately