如何在Java中四舍五入整数除法并产生int结果？

formatting types math java

2022-08-31 09:04:04

我刚刚写了一个小方法来计算手机短信的页数。我没有选择四舍五入使用，老实说，它似乎非常丑陋。Math.ceil

这是我的代码：

public class Main {

/**
 * @param args the command line arguments
 */
public static void main(String[] args) {
   String message = "today we stumbled upon a huge performance leak while optimizing a raycasting algorithm. Much to our surprise, the Math.floor() method took almost half of the calculation time: 3 floor operations took the same amount of time as one trilinear interpolation. Since we could not belive that the floor-method could produce such a enourmous overhead, we wrote a small test program that reproduce";

   System.out.printf("COunt is %d ",(int)messagePageCount(message));



}

public static double messagePageCount(String message){
    if(message.trim().isEmpty() || message.trim().length() == 0){
        return 0;
    } else{
        if(message.length() <= 160){
            return 1;
        } else {
            return Math.ceil((double)message.length()/153);
        }
    }
}

我真的不喜欢这段代码，我正在寻找一种更优雅的方法来做到这一点。有了这个，我期待3而不是3.0000000。有什么想法吗？

答案 1

使用结果并将其转换为 int：Math.ceil()

这仍然比使用abs（）避免双倍更快。
处理负数时，结果是正确的，因为 -0.999 将向上舍入为 0

例：

(int) Math.ceil((double)divident / divisor);

答案 2

要对整数除法进行舍入，可以使用

import static java.lang.Math.abs;

public static long roundUp(long num, long divisor) {
    int sign = (num > 0 ? 1 : -1) * (divisor > 0 ? 1 : -1);
    return sign * (abs(num) + abs(divisor) - 1) / abs(divisor);
}

或者如果两个数字都是正数

public static long roundUp(long num, long divisor) {
    return (num + divisor - 1) / divisor;
}