Summary of floor, round and ceil of Java math

Floor returns the maximum integer not greater
Round is the calculation of 4 homes and 5 homes, and the input is an integer greater than it (when-1.5 is displayed, the result obtained after rounding is not what we expect, the solution is to first take the absolute value for him, and then use the round method)

Round method, which indicates "Rounding". The algorithm is math. floor (x + 0.5), which adds 0.5 to the original number and then rounds down. Therefore, math. the result of round (11.5) is 12, math. the result of round (-11.5) is-11.

Ceil is the smallest integer not less than him.

Look at the example

	Math. Floor	Math. Round	Math. ceil
1.4	1	1	2
1.5	1	2	2
1.6	1	2	2
-1.4	-2	-1	-1
-1.5	-2	-1	-1
-1.6	-2	-2	-1

The test procedure is as follows:

Public class mytest {<br/> Public static void main (string [] ARGs) {<br/> double [] Nums = {1.4, 1.5, 1.6,-1.4, -1.5,-1.6 }; <br/> for (double num: Nums) {<br/> test (Num ); <br/>}</P> <p> Private Static void test (double num) {<br/> system. out. println ("math. floor ("+ num +") = "+ math. floor (Num); <br/> system. out. println ("math. round ("+ num +") = "+ math. round (Num); <br/> system. out. println ("math. ceil ("+ num +") = "+ math. ceil (Num); <br/>}< br/>}

Running result
Math. Floor (1.4) = 1.0
Math. Round (1.4) = 1
Math. Ceil (1.4) = 2.0
Math. Floor (1.5) = 1.0
Math. Round (1.5) = 2
Math. Ceil (1.5) = 2.0
Math. Floor (1.6) = 1.0
Math. Round (1.6) = 2
Math. Ceil (1.6) = 2.0
Math. Floor (-1.4) =-2.0
Math. Round (-1.4) =-1
Math. Ceil (-1.4) =-1.0
Math. Floor (-1.5) =-2.0
Math. Round (-1.5) =-1
Math. Ceil (-1.5) =-1.0
Math. Floor (-1.6) =-2.0
Math. Round (-1.6) =-2
Math. Ceil (-1.6) =-1.0