Datatypes
As the name suggests, data-type specifies the type of the data present in the variable. Variables must be declared with a data-type.
There are two groups of Data types in Java.
i. Primitive data types
Primitive data types specifies the type and size of the data present in variables and they don't have additional methods.
| Data type | Description | Range | Size |
|---|---|---|---|
| int | used to store whole numbers | -2,147,483,648 to 2,147,483,647 | 4 bytes |
| short | used to store whole numbers | -32,768 to 32,767 | 2 bytes |
| long | used to store whole numbers | -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 | 8 bytes |
| byte | used to store whole numbers | -128 to 127 | 1 byte |
| float | used to store fractional numbers | 6 to 7 decimal digits | 4 bytes |
| double | used to store fractional numbers | 15 decimal digits | 8 bytes |
| boolean | can either store true or false | either true or false | 1 bit |
| char | used to store a single character | one character | 2 bytes |
Examples
1. Integer data type
int is used to store whole numbers from -2147483648 to 2147483647.
int x = 99999;
System.out.println(x);
2. Short data type
short is used to store whole numbers from -32768 to 32767
short x = 999;
System.out.println(x);
3. Long data type
Long is used when int is not enough to hold the data and can store whole numbers from -9223372036854775808 to 9223372036854775807. You should put L at the end of the value.
long x = 99999999999L;
System.out.println(x);
4. Byte data type
Byte can store whole numbers from -128 to 127. This data type is used to save memory and is used when the value is with in -128 to 127.
byte x = 99;
System.out.println(x);
5. Double data type
Double is used store fractional numbers in the range 1.7e−308 to 1.7e+308. You should put d at the end of the value.
double x = 99.99d;
System.out.println(x);
6. Boolean data type
Boolean data type is used only when the value is either true or false.
boolean isAvailable = true;
System.out.println(isAvailable);
7. Char data type
char data type is used to store single character. Single quotes are used to represent characters.
char division = 'A';
System.out.println(division);
ii. Non-Primitive data types
Non-primitive data types specifies the complex data values and it can have additional methods. Usually non-primitive data types are created by the developer (except for String).
For example, strings, arrays and classes can be referred as Non-primitive data types and are discussed in later sections.