Kinds of Data Type in Java
Primitive type
- Java provides 8 kinds of Primitive type.
- Primitive data types cannot contain null
- actual value will saved in Stack memory.
| data type | base memory | defult value | range of data | range of data in number |
|---|---|---|---|---|
| boolean | 1 byte | false | true, false | true, false |
| byte | 1 byte | 0 | -127 ~ 128 | $-2^{7}$~ $(2^{7}-1)$ |
| short | 2 byte | 0 | -32,768 ~ 32,767 | $-2^{15}$~ $(2^{15}-1)$ |
| int | 4 byte | 0 | -2,147,483,648 ~ 2,147,483,647 | $-2^{31}$~ $(2^{31}-1)$ |
| long | 8 byte | 0L | -9,223,372,036,854,775,808 ~ 9,223,372,036,854,775,807 | $-2^{63}$~ $(2^{63}-1)$ |
| float | 4 byte | 0.0F | 0.000…0034 ~ 3400…000 | $3.4 \cdot 10^{-38}$ ~ $3.4 \cdot 10^{38}$ |
| double | 8 byte | 0 | 0.00000000…00017 ~ 17000…000000000 | $1.7 \cdot 10^{-308}$~$1.7 \cdot 10^{308}$ |
| char | 2 byte | ‘\u0000’ | 0~65,535 | $0$ ~ $(2^{16}-1)$ |
Reference type
- If not primitive type, it is Reference type.
- Reference data types can contain null
- address will saved in Heap memory.
| data type | base memory | defult value |
|---|---|---|
| Array | 4 byte | NULL |
| Enumeration | 4 byte | NULL |
| Class | 4 byte | NULL |
| Interface | 4 byte | NULL |