Primitive Types:
1) byte:
size: 8-Bit = 1-Byte
range: -128~+127
usage:
1> The byte data type can be useful for saving memory in large arrays, where memory saving actually matters.
2> They can also be used in place of int where their limits help to clearify your code. The fact that a variable's range is limited can serve as a form of documentation.
2) short:
size: 16-Bit = 2-Byte
range: -32768~+32767
usage:
1> You can use short to save memory in large arrays, in situation memory where memory savings acutally matters.
3) int:
size: 32-Bit = 4-Byte
range: -(2^31)~+(2^31-1)
4) long:
size: 64-Bit = 8-Byte
range: -(2^63) ~ +(2^63-1)
5) float:
size: single-precision 32-Bit IEEE 754 floating point
range: Its range of value is beyond the scope of this discussion.
usage: Use a float if you need to save memory in large arrays of floating point numbers.
This data type should never be used for precise values, such as currency.
For that, you need to use the java.math.BigDecimal class instead.
6) double:
size: double-precision 64-Bit IEEE 754 floating point.
range: Its range of values is beyond the scope of this discussion.
usage: For decimal values, this data type is generally the default choice.
As mentioned above, this data type should never be used for precise values.
7) boolean:
size: represent one-bit of information, but its size isn't precisely defined.
range: true/false
usage: Use this data type for simple flags that track true/false conditions.
8) char:
size: 16-Bit = 2 Byte
range: '\u0000' or 0 inclusive ~ '\uffff' or 65535 inclusive
Default Values:
Data Type Default Value (for fields)
| byte | 0 |
| short | 0 |
| int | 0 |
| long | 0L |
| float | 0.0f |
| double | 0.0d |
| char | '\u0000' |
| String (or any object) | null |
| boolean | false |
Reference Links:
1) http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html