Data Types And Initializing the Variables

DATA TYPES:-

JAVA has main four types of Data. They are as follows:-

1) INTEGER:- This group contains byte, short, int and long which represents the whole number.

2)FLOATING-POINT NUMBER:- This group contain float and double which represents the fractional number.

3) CHARACTER:- This group contains char and string which represents symbols in character.

4) BOOLEAN:- This group contains Boolean which represents true / false value.

Width and Range of above data types are shown in following Table:-

NAME	WIDTH	RANGE
Byte	8	–128 to 127
Short	16	–32,768 to 32,767
Int	32	–2,147,483,648 to 2,147,483,647
Long	64	–9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
Float	32	1.4e-045 to 3.4e+038
Double	64	4.9e–324 to 1.8e+308

INITIALIZING THE VARIABLES:-

Syntax:-

Type identifier variable_name;

OR

Syntax to initialize the variable except character and string variable:-

Type identifier variable_name = value;

For Character variable:-

Type identifier variable_name = ‘value’;

For String variable:-

Type identifier variable_name = “value”;

Here type identifier means type of data. E.g. int, char, float etc.

e.g.

int x, y, z;                               // declares three integers x, y, and z.

int a = 3, b, c = 5;                 // declares three integers by initializing two of them i.e. a and c.

byte t = 22;                           // initializes t.

double pi = 3.14;                 // declares an approximate value of pi.

char s = 's';                            // the variable s has the value 's'.

float f = 5.26F                       // initializes f. It is important to write “F” to initialize the float value.

Float k = 20.145F                 // initializes k.

String r = “JAVA”;                 // initializes r.

You also can initialize the variable dynamically. Check the following program to clear the idea.

class DynInit

{

public static void main(String args[])

{

double a = 169.0;

double b = Math.sqrt(a);

System.out.println("Square Root is " + c);

}

}

Above program has two variable, a and b. Variable a initialize by constant and variable b is initialize dynamically.

Variable b can be initialize by the computing value of Math.sqrt(a) function.