Variables

Variables are elements in code that can store stuff.

Data Types

Data in Java have data types (duh) to help differentiate objects from each other. There are two general categories of data types— Primatives and Composites. We'll also go over commonly used data types here.

Primatives

Data Type	Description	Example(s)
Integer (int)	Whole numbers, no decimals.	int num = 1;
Doubles	numbers with decimals. Also known as floats.	double num = 0.24;
Characters (chars)	Digits, icons, or letters. Note that a digit's value is different from what it looks like.	char c = 'A'; char fourAsDigit = '4'; (not the same as the number 4)
Booleans	Logic, toggleable between true and false. Used in boolean zen (will explain later, don't worry)	boolean incomingTest = true; boolean studying = false;

Composites

Composites generally are made from groups of smaller primitives. Due to their complexity, (except for strings) they are treated differently. Here are some noticeable ones:

Data Type	Description	Example(s)
Strings	Store text (multiple chars)	string intro = "Hello World!"
Arrays	Store multiple values of the same type	int[] array = {5, 4, 3, 2, 1} char[] msg = {'H', 'E', 'L', 'P'}
User-Created Data Types	Don't worry about this— we'll cover it later. Its fields and purposes could change depending on what it's used for.	Object o = new Object() Animal cat = new Animal("Cat");

Creating Variables

All you need to do is:

[data type] variableName;
/* example */
int number;

Yep. That's it. All you'll need to do is