Java Quick Reference - Language Fundamentals

Language Fundamentals

Operators and Assignments

Flow Control and Exceptions

Declarations and Access Control

Garbage Collection

Overloading and Overriding

Threads

The java.lang Package

The java.util Package

The java.awt Package

The java.io Package

References

Miscellaneous Notes

Tips & Traps

Mock Exams

Language Fundamentals - Primitive Types

Data Type	Bit Size	Range	Min/Max values	Default
boolean	n/a	true or false	n/a	false
byte	signed 8-bit integer	-(2⁷) to 2⁷-1	-128 to 127	0
char	16-bit Unicode 2.0 character	0 to 2¹⁶-1	0 to 65,535	\0000
short	signed 16-bit integer	-(2¹⁵) to 2¹⁵-1	-32,768 to 32,767	0
int	signed 32-bit integer	-(2³¹) to 2³¹-1	-2,147,483,648 to 2,147,483,467	0
long	signed 64-bit integer	-(2⁶³) to 2⁶³-1	-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807	0l
float	signed 32-bit floating-point	NEGATIVE_INFINITY to POSITIVE_INFINITY	Can also have the value NaN (Not a number)	0.0f
double	signed 64-bit floating-point	NEGATIVE_INFINITY to POSITIVE_INFINITY	Can also have the value NaN (Not a number)	0.0d

arithmetic with floating-point numbers will never throw an exception; instead one of the constant values: NEGATIVE_INFINITY, POSITIVE_INFINITY, or NaN are returned (BB pg 123)
Variables declared as primitive types are not object references. They are placeholders for storing primitive values (JJ pg29)
by default integer values are of type int and floating-point values are of type double
float values are single-precision
double values are double-precision

Wrapper classes

all the primitive types have corresponding wrapper classes which allow you to create objects of type Integer, Boolean, Float, etc.
the wrapper classes have the same names as the primitive types except they begin with a Captial.

!!! Warning - do NOT mix up the Types !!!

    boolean b;
    
IS NOT THE SAME AS

    Boolean b;              
        
You can say:    boolean b = true;
You CANNOT say: 
    Boolean b = true;  -> Boolean is a class, must use
    Boolean b = new Boolean(true);

Also see

Differentiate between reference and primitive types

Traps

variables of primitive types handled as Objects

Source	Package	Import	Class	Interface	Constructors
Methods	main()	Identifiers	Keywords	Defaults	Arrays
Primitives	# Literals	char Literal	String Literals	Class Literals