Java and JS take integer summary

Java rounding

　　(-) Math class

1.Math.floor : Returns a double value that is less than the maximum integer of the target value.

Example: String v = "13.5"; Math.floor (double.parsedouble (v));

Results:0.

String v = "13.5"; Math.floor (Double.parsedouble (v));

Result:-14.0.

2.Math.ceil : Returns a double value that is greater than the minimum integer of the target value.

Example: String v = "13.5"; Math.ceil (double.parsedouble (v));

Results:0.

String v = "13.5"; Math.ceil (Double.parsedouble (v));

Result:-13.0.

3.Math.rint: Returns a double value, rounded, but even 0.5 takes adjacent even

Example: String v = "13.5"; Math.rint (double.parsedouble (v));

Results:0.

String v = "14.5"; Math.rint (Double.parsedouble (v));//even decimal is 0.5

Results: 14.0.

4.Math.Round: Rounding, but the algorithm is Math.floor (x+0.5), will be the original number plus 0.5 and then rounding down.

Example: String v = "13.5"; Math.Round (double.parsedouble (v));

Results: 14.

String v = "13.5"; Math.Round (Double.parsedouble (v));

Result:-13. -13.6 is-14

　Two DecimalFormat class and NumberFormat class

　　　　Rounded, but even when 0.5 takes an even number adjacent.

Example: String v = "13.5"; New DecimalFormat ("0"). Format (double.parsedouble (v)); or numberformat.getintegerinstance (). Format (double.parsedouble (v));

Results: 14.

String v = "14.5"; Even-numbered decimals are 0.5

Results: 14.

　

　Three BigDecimal Class (recommended)

(1) bigdecimal.round_half_up : Rounding

Example: String v = "13.5"; New BigDecimal (v). Setscale (0, bigdecimal.round_half_up);

Results: 14.

(2) bigdecimal.round_up: Rounding away from zero rounding mode

　　　　　　Example: String v = "13.5"; New BigDecimal (v). Setscale (0, bigdecimal.round_up);

Results: 14.

String v = "13.5"; New BigDecimal (v). Setscale (0, bigdecimal.round_up);

Result:-14.

(3) bigdecimal.round_down: Rounding mode close to 0

Example: String v = "13.5"; New BigDecimal (v). Setscale (0, Round_down);

Results: 13.

String v = "13.5"; New BigDecimal (v). Setscale (0, Round_down);

Result:-13.

(4) Bigdecimal.round_half_down: Six in five homes

Example: String v = "13.5"; New BigDecimal (v). Setscale (0, Round_half_down);

Results: 13.

String v = "13.6"; New BigDecimal (v). Setscale (0, Round_half_down);

Results: 14.

(5) Bigdecimal.round_floor: The largest integer less than the target value

Example: String v = "13.5"; New BigDecimal (v). Setscale (0, Round_floor);

Results: 13.

String v = "13.5"; New BigDecimal (v). Setscale (0, Round_floor);

Result:-14.

JS rounding

　　1.math.ceil: The smallest integer greater than the target value Math.ceil (12.5)------>13,-12.5------>-12

2.math.floor: Maximum integer math.floor (12.5) less than the target value------>12,-12.5------>-13

3.math.round: Rounding Math.Round (12.4)------>12,12.5------>13

4.parseint:parseint (12.5)------>12

　　　　　　

　　　　　　

　　　　

Java and JS take integer summary