Java - Language Syntax 090820

PRIMITIVE DATA TYPES

Integer		Minimum Value	Default	Maximum Type Value
byte		-128 (byte)	0	127
short	2 bytes	-32,768 (short)	0	32,767
int	4 bytes	-2,147,483,648	0	2,147,483,647
long	8 bytes	-9,223,372,036,854,775,808	0	9,223,372,036,854,775,807

 

float (4 bytes with 7 digits fractions)

double (8 bytes with 15 digits fractions)

 

char (are specified between SINGLE quotation marks)

String (are specified between DOUBLE quotation marks)

 

Boolean

 

59 reserved words, including all of the data types.

 

CONSTANT

final

 

ARRAYS

One-dimensional array is a numbered list of variables of the same type.

 

String[] dinnerGuests = new String[8];

dinnerGuests[0] = “Fred”;

dinnerGuests[1] = “Jane”;

…

 

String dinnerGuests[] = {“Fred”, “Jane”, “Michael”, “Brenda”, … }

 

int twoDiArray[][]={{10,9,8,7,6,5,4,3,2,1},{}}; // Declare a two dimensional array

int[][][] threeDiArray;            // Uninitialized 3D array.

 

Array indexes must either be type int (32-bit integer) or be able to be cast as an int. As a result, the largest possible array size is 2,147,483,647.

 

STRING

String in Java is represented as a class, not as an array of characters, so it has methods such as length() and substring().

 

OPERATORS

+ Addition

- Subtraction

* Multiplication

/ Division

% Integer Remainder

++ increment operators

-- decrement operators

 

double * (float, long, int, short, byte) = double

double mySalary = 1000.65

int approxSalay = (int) mySalary //called casting process

 

== is equal to

!= is not equal to

< is less than

> is more than

<= is less than or equal to

>= is greater than or equal to

&& AND

|| OR

 

CONTROL STRUCTURES

if ( ) { … } else { … }

while ( ) { … }

do { … } while ( )

for (int i=10; i=0; i--) { … }

switch