- Integers:
- When an arithmetic operation
contains 2 integer values,
convert any
lower precision integer type
to int type
- When an arithmetic operation contains a long value, convert any lower precision integer type to long type
- When an arithmetic operation
contains 2 integer values,
convert any
lower precision integer type
to int type
- Floating point numbers (float and double):
- When an arithmetic operation contains 2 floating point values, convert any lower precision float type to double type
- Mixed integer and floating point numbers:
- When an arithmetic operation
contains one floating point value and
one integer value:
- convert the integer value to double
- convert the lower precision float type to double type (if needed)
- When an arithmetic operation
contains one floating point value and
one integer value:
- Assignment operation:
variable = expression ; ^^^^^^^^ ^^^^^^^^^^ type1 type2 (type1 and type2 can be different)Automatic Promotion rule:
- If the range of values of type1 contains the range of values of type2, then Java will perform an automatic promotion from type2 ⇒ type1 for the assignment operation
We call such assignemts safe.... (because the conversion will not lose any accuracy or a very small amount of accuracy).
- The following assignments
are safe
(and Java will perform
an automatic conversion operation
for you):
Note:
- The conversions
of int ⇒ float and
long ⇒ float
will lose a very small
amount of accuracy
(instead of a whole number like 4, the floating number
will be 3.99999... or
4.000000000001 or something like that).
- The loss of accuracy is
very small but the
gain in convenience is
tremendous
So Java deems these conversions as safe
- The conversions
of int ⇒ float and
long ⇒ float
will lose a very small
amount of accuracy
(instead of a whole number like 4, the floating number
will be 3.99999... or
4.000000000001 or something like that).
- The following assignments
are unsafe
(and you
must use
a casting operator
to make the assignment legal):
