Ohne Titel

Java Separators

Primitives

Primitives : Simple non-object programming elements that represent numbers and simple values such as true and false

Variables

placeholders whose contents can change

Data placeholders. every variable in java must have a declared type of either;

-Reference type: provides a reference to an object

-primitive type: holds a primitive

also, a variable has a name or identifier

You declare a variable by writing the type then the name with a ; afterwards and it is also possible to assign a value to a variable at the same time the variable is declared.

for example. byte x = 12;

Constants

placeholders whose contents cannot change

when the values of constants are assigned they cannot be changed, you declare a constant with the keyword “final”

example: final int ROW_COUNT = 50;

Java Keywords

Literals

there are 3 types, primitive literals, string literals, and null literals

Integer Literals

used to assign values to variables of type byte, short, int, and long. remember do not assign a value that exceeds the capacity of a variable (see ranges in Java Primitive table above)

for a “long” example  long a = 9898997L; notice the “L” at the end

Floating – Point Literals

ex of numbers are .4, 1.23, .5e^10

a floating number point has the following parts; a whole number part, a decimal point, a fraction part, and optional exponent

includes floats and doubles. if you do not include the “f” then it becomes a double

ex of float: 2e1f

8.f

0f or 9.001e+12f (plus is optional – is not

Character literals

a Unicode character or an escape sequence enclosed in single quotes. an escape sequence is the representation of a Unicode character that cant be entered using the keyboard or has a special function in java.

exampls of character literals that are escape sequences

‘ \ b ’ backspace character ‘ \ t ’ tab character ‘ \ \’ backslash

‘ \’ ‘ the single quote ‘ \ “ ‘ the double quote ‘ \ n ‘ linefeed

‘ \ r ‘ carriage return

Boolean literals

2 values either true or false

example which declares a boolean variable “includeSign” and assigns it value “true” boolean includeSign = true;