Computers programs store data in variables. A data type or simply type is the type of
data that can be stored in a variable.
Java is a strongly typed
language. That means that when we declare a variable in Java, we must always specify
its type.
java data types are
divided into two groups:
- Primitive
types or Basic Types
- Non primitive types or Reference
types
Primitive data types are built in to the programming language. This data types are predefined by
the language.
Reference data types are the programmer-defined
classes and the types defined by classes in the Java API.
There are eight primitive
data types in Java:
Data Type
|
Description
|
Size (Bytes)
|
Range
|
Default Value
|
Wrapper Class
|
byte
|
Signed
integer
|
1
|
-128
to 127
|
0
|
Byte
|
short
|
Signed
integer
|
2
|
-32.768
to 32.767
|
0
|
Short
|
int
|
Signed
integer
|
4
|
-2147483648 to 2147483647
|
0
|
Integer
|
long
|
Signed
integer
|
8
|
-9223372036854775808 to
9223372036854775807
|
0
|
Long
|
float
|
Single-precision
floating point
|
4
|
±
3.4x10-38 to ± 3.4x1038
|
0.0
|
Float
|
double
|
Double-precision
floating point
|
8
|
±
1.8x10-308 to
± 1.8x10308 |
0.0
|
Double
|
char
|
Unicode
character
|
2
|
\u0000
to \uFFFF
|
\u0000
|
Character
|
boolean
|
Logical
data type
|
-
|
true
- false
|
false
|
Boolean
|
INTEGER DATA TYPES
There are
four integer data types: byte, short, int, long.
For example:
int a = 3;
byte n1, n2;
short x = -1;
FLOATING POINT DATA TYPES
There are two floating point data types: float,
double.
For example:
float weight;
double price;
double amount = 1.7E4; // 1.7 * 104
double z = .123; //0.123
CHARACTER DATA TYPE
The character data type is represented by the char type.
The char type is used to store a Unicode character
in the range \u0000 to \uFFFF.
The
first 127 Unicode characters correspond with the ASCII code.
For example:
char ch;
char ch1 = 'z';
char ch2 = '\u0061'; //
unicode for ‘a’
BOOLEAN DATA TYPE
The
following declares two boolean variables:
boolean first = true;
boolean last = false;
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