roundToDouble method Null safety

Returns the integer double value closest to the double value.

Returns null if the double value is null

Rounds away from zero when there is no closest integer: (3.5).roundToDouble() == 4 and (-3.5).roundToDouble() == -4.

If this is already an integer valued double, including -0.0, or it is not a finite value, the value is returned unmodified.

For the purpose of rounding, -0.0 is considered to be below 0.0, and -0.0 is therefore considered closer to negative numbers than 0.0. This means that for a value d in the range -0.5 < d < 0.0, the result is -0.0.

print(3.0.roundToDouble()); // 3.0
print(3.25.roundToDouble()); // 3.0
print(3.5.roundToDouble()); // 4.0
print(3.75.roundToDouble()); // 4.0
print((-3.5).roundToDouble()); // -4.0