DATA TYPES IN JAVA PROGRAMMING - tccicomputercoaching.com

DATA TYPES IN JAVA PROGRAMMING tccicomputercoaching.com

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tccicomputercoaching.com • In this article we will learn about the java data types. • Variable is a memory location where we can store the data. There are three types of variables: local, instance and static. There are two types of data types in java, primitive and non-primitive.

tccicomputercoaching.com Data Types in Java • In general every programming language is containing three categories of data types. They are 1. Fundamental or primitive data types 2. Derived data types 3. User defined data types.

tccicomputercoaching.com Primitive data types • Primitive data types are those whose variables allows us to store only one value but they never allows us to store multiple values of same type. • This is a data type whose variable can hold maximum one value at a time.

tccicomputercoaching.com Data Type

Default Value

Default size

boolean

false

1 bit

char

‘\u0000’

2 byte

byte

0

1 byte

short

0

2 byte

int

0

4 byte

long

0L

8 byte

float

0.0f

4 byte

double

0.0d

8 byte

tccicomputercoaching.com • The Java programming language is statically-typed, which means that all variables must first be declared before they can be used.

This involves stating the variable’s type and name, as you’ve already seen: • int gear = 1; • int a; // valid • a=10; // valid

tccicomputercoaching.com • User defined data types • User defined data types are those which are developed by programmers by making use of appropriate features of the language.

• In java both derived and user defined data type combined name as reference data type.

• Student s = new Student();

tccicomputercoaching.com • Integer Data Type: Data Type

Size

Range

1

Byte

1

+ 127 to -128

2

Short

2

+ 32767 to -32768

3

Int

4

+ x to – (x+1)

4

Long

8

+ y to – (y+1)

tccicomputercoaching.com • Char Data Type Data Type

Size(Byte)

Range

Char

2

232767 to -32768

• Float Data Type Data Type

Size

Range

Float

4

+2147483647 -2147483648

Double

8

+ 9.223*1018

Number of decimal places to

8 16

tccicomputercoaching.com Boolean Data Type • Boolean data type takes zero bytes of main memory space because Boolean data type of java implemented by Sun Micro System with a concept of flip – flop.

• A flip – flop is a general purpose register which stores one bit of information (one true and zero false).

tccicomputercoaching.com Default Values • It’s not always necessary to assign a value when a field is declared.

Fields that are declared but not initialized will be set to a reasonable default by the compiler. • Generally speaking, this default will be zero or null, depending on the data type. Relying on such default values, however, is generally considered bad programming style.

tccicomputercoaching.com User Defined Data Type: • Typedef • A typedef associates a name with another data type. Here is the syntax of an IDL typedef: • typedef type identifier; • The type can be any basic IDL data type, a user-defined data structure.

• typedef int unit;

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