Basic Java Language
This lesson discusses the basics of the Java language, including variables, primitives, operators, statements and Java writing conventions.
Variables
Variables are used to store data that can change. There are two main categories of variables, reference variables and primitive variables. Reference variables are place holders for objects (More on objects in Lesson 4, Java Objects and Classes.) Primitive variables are given a value of a primitive, a basic value. Variables are all given a type when they are declared, such as "integer" or "string".
Primitive Data Types
Primitives are the simplest type of data. Primitives consist of numbers, letters and strings of letters. The following table shows all the types of primitives.
| Primitive | Description | Values |
| byte | A brief, 8-bit integer | Whole numbers -128 through 127 |
| short | A short, 16-bit integer | Whole numbers -32,768 through 32,767 |
| int | A 32 bit integer | Whole numbers -2,147,483,648 through 2,147,483,647 |
| long | A long, 64 bit integer | Whole numbers -9,223,372,036,854,775,808 through 9,223,372,036,854,775,807 |
| float | Single-percision floating poing (32-bit IEEE 754) | Smallest positive non-zero: 14e-45, Largest positive non-zero: 3.4028234e38 |
| double | Double-percision floating point (64-bit IEEE 754) | Smallest positive non-zero: 4.9e-324, Largest positive non-zero: 1.797693157e308 |
| char | A single character | All Unicode characters |