Lesson 7 +10 XP

Java Data Types

A data type defines what kind of value a variable can hold. Java has two groups: primitive types and reference types.

Primitive types are built into Java and store single values:

Type	Size	Stores
`byte`	1 byte	Whole numbers from -128 to 127
`short`	2 bytes	Whole numbers from -32768 to 32767
`int`	4 bytes	Whole numbers from -2147483648 to 2147483647
`long`	8 bytes	Very large whole numbers
`float`	4 bytes	Decimal numbers
`double`	8 bytes	Decimal numbers with more precision
`boolean`	1 bit	`true` or `false`
`char`	2 bytes	A single character, written in single quotes

int myNum = 5;
float myFloat = 5.99f;
char myLetter = 'D';
boolean myBool = true;
String myText = "Hello";

Both store decimals. double is the default and is more precise. Use double unless you have a reason not to.

Primitive types store a single value.
Common types: int, double, boolean, char, and the String reference type.
char uses single quotes; String uses double quotes.