Java Primitive Types
Consider the following Java primitive types and take note of the type’s size, e.g., 8-bit. For this post, we can ignore boolean, and char as they are not numeric types.
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| Keyword | Type | Example |
|---|---|---|
| boolean | true or false | true |
| byte | 8-bit integral value | 123 |
| short | 16-bit integral value | 123 |
| int | 32-bit integral value | 32-bit integral value |
| long | 64-bit integral value | 123 |
| float | 32-bit floating-point value | 123.45f |
| double | 64-bit floating-point value | 123.456 |
| char | 16-bit Unicode value | 'a' |
Given the following table of Java primitive types, Java follows when applying operators to data types.
- If two values have different data types, Java will automatically promote one of the values
to the larger of the two data types. - If one of the values is integral and the other is floating-point, Java will automatically
promote the integral value to the floating-point value’s data type. - Smaller data types, namely
byte,short, andchar, are first promoted tointany time
they’re used with a Java binary arithmetic operator, even if neither of the operands is
int. - After all promotion has occurred and the operands have the same data type, the resulting
value will have the same data type as its promoted operands.
Rule 1 Examples:
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1 2 3 4 | int x = 1; long y = 33; // The result of x * y is of type long |
1 2 3 4 5 | float y = 14f; double x = 12.3; // The result of x * y is of type double |
Rule 2 Examples:
1 2 3 4 | int y = 3; double x = 11.3; // The result of x * y is of type double |
Rule 3 Examples:
1 2 3 4 | byte y = 3; short x = 1; int f = y * x; short g = y * x; // Type mismatch: cannot convert from int to short |
Rule 4 Examples:
Rule 4 simple means the result of an arithmetic operation will have the same type as the type all operands promoted to. It is based on the first three rules.
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