Data types are divided into two groups :
- Primitive data types
- Non-Primitive data types
Primitive Data Types
This data type specifies the size and type of variable values, and it has no additional methods.
There are eight primitive data types :
| Data Type | Size | Description |
|---|---|---|
| byte | 1 byte | Stores whole numbers from -128 to 127 |
| short | 2 bytes | Stores whole numbers from -32,768 to 32,767 |
| int | 4 bytes | Stores whole numbers from -2,147,483,648 to 2,147,483,648 |
| long | 8 bytes | Stores whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,808 |
| float | 4 bytes | Stores fractional numbers. Sufficient for storing 6 to 7 decimal digits |
| double | 8 bytes | Stores fractional numbers. Sufficient for storing 15 decimal deigits |
| boolean | 1 bit | Stores true or false values |
| char | 2 bytes | Stores a single character/letter or ASCII values |
Non-Primitive Data Types
(Also known as Reference Types)
- String
- Arrays
- Classes
Float or Double ?
The precision of a floating point value indicates how many digits the value can have after the decimal point. The precision of float is only six or seven decimal digits, while double variables have a precision of about 15 digits. Therefore it is safer to use double for most calculations.
Boolean Types
- YES / NO
- TRUE / FALSE
- ON / OFF
- This is used for conditional testing
Character Types
- Used to store single character
- Surrounded by single-quotes
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