Three methods of the Java Math class ceil floor round usage
- 2021-10-24 22:43:21
- OfStack
ceil, floor, round Usage of Math Class
ceil () method
It means rounding up, and the result of Math. ceil (12.3) is 13, and the result of Math. ceil (-12.7) is-12;
floor () method
It means rounding down, and the result of Math. floor (12.7) is 12, and the result of Math. floor (-12.3) is-13;
round () method
It means "4 round 5 in", the result of Math. round (12.3) is 12, and the result of Math. round (-12.7) is-13;
Summary of floor, round and ceil for Math
floor returns the largest integer not greater than
round is the calculation of 4 rounded by 5 integers, and the integer is greater than it when entering
round method, which means "4 rounding 5 inputs", the algorithm is Math. floor (x+0.5), that is, adding 0.5 to the original number and rounding it down, so the result of Math. round (11.5) is 12, and the result of Math. round (-11.5) is-11.
ceil is the smallest integer not less than it
Look at examples
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 {
public static void main(String[] args) {
double[] nums = { 1.4, 1.5, 1.6, -1.4, -1.5, -1.6 };
for (double num : nums) {
test(num);
}
}
private static void test(double num) {
System.out.println("Math.floor(" + num + ")=" + Math.floor(num));
System.out.println("Math.round(" + num + ")=" + Math.round(num));
System.out.println("Math.ceil(" + num + ")=" + Math.ceil(num));
}
}
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