CS Primitive Types

primitive type

a basic data type that Java predefines.
- takes up different amounts of memory

Object reference type

Only need enough memory to hold a pointer to the object in question
- Declared with either a name of an interface or a class

8 primitive types (in order)

byte, short, int, long, float, double, char, boolean

Byte

(byte) 8 bits of interger

Short

(short) 16 bits of interger

Interger

(int) 32 bits of interger

Long

(long) 64 bits of interger

Float

(float) 32 bits of floating point

Double

(double) 64 bits of floating point

Character

(char) 16 bits of a letter

Boolean

(boolean) true or false

Variables

Fields of memory inside an object
- Can only hold one type of thing
- type, name
- Each variable can be seen by as few things as possible for as short a period of possible

Private declaration

Only seen inside the class

Protected declaration

Only seen in the class, package, and subclasses

Public declaration

Visible to all

Method

Declared with a return type, a name, and a list of parameters
- Each parameter is declared with a type and a name

Constructor method

Method that creates a new instance of a class
- Two kinds (object constructor and arrary object constructor)
- Always begins with the word new

Object constructor

Method that has the same name as the class and no declared return type

Array object constructor

Not a method we write, but we must specify that kind of thing the array holds and how many of that items are in said array

Array

A sequence of values of a given type.
-An object w/ a fixed size once it is created
- [array]

Examples of how arrays can e made (two)

- int[ ] myArray = we int[9]; (nine element arry of ints)
- int[ ] myArray = { 1, 1, 2, 5, 8, 13, 21, 34}; (nine element array w/ specific values)

Two dimensional array

An array of arrays
carton = new Egg[2][6];
for(int row = 0; row < carton.length; ++row){
carton[row][column] = we Egg();
}