Data types

 

Declaring and assigning variables
Integers
Floating point types
Other
Constants
Strings

 

Declaring and assigning variables

Declare variables:

int myInteger;
char ch;

Assigning variables:

ch = 'Y';

Declaration and assignment can be done at the same line:

int i = 10;

 

Integers

int 4 bytes -2,147,483,648 to 2,147,483,64
short 2 bytes -32,678 to 32,767
long 8 bytes 9,223,372,036,854,775,808L to 9,223,372,036,854,775,807L
byt 1 byte -128 to127

Floating point types

float 4 bytes 6-7 significant digits
double 8 bytes 15 significant digits

Other

char Note that single quotes are used to denote char constants. 'H' is a char, "H" is a string.
boolean Has two values: true and false

Constants

Use the keyword final to denote a constant:

final double myConstanmts = 2.45;

A constant can be defined as a class constant so that it is vailable to all methods inside the class. Class constants are defined as static final:

public static final double myCon = 8.57;

Strings

Note that strings are not a built in dadat type. Instead the standard java library contains a predefined String class.

String e = "";

String hallo = "Hallo world";

 

 

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