java - 制定划分的一般规则

Question

我有以下功能:

public static void main(String[] args) {
        int interval = 23950; 

        System.out.println (Math.round(weekInterval/1000.00)*1000);



    }

该函数所做的就是将数字(间隔)四舍五入到最接近的百或千的倍数等。

现在数字间隔可能会发生变化，可以从数百到数十亿不等，我想设定一个除法的通用规则:

这样

Math.round(weekInterval/placeholder)*placeholder)

有什么想法吗？

编辑:

到目前为止，这是我利用有限的知识得出的结论——请耐心等待，这可能效率很低:

public static void main(String[] args) {
        int weekInterval = 2500; 
        StringBuilder sbr = new StringBuilder(); 
        int len = String.valueOf(weekInterval).length();
        String num = "1"; 
        for(int i = 2; i<=len; i++){
            
            sbr.append("0"); 
        }
        System.out.println("Number is "+sbr.toString()); 
        System.out.println("Number is "+num+sbr.toString()); 
        
        int placeholder = Integer.valueOf(num+sbr.toString());
        System.out.println((weekInterval + placeholder/2)/placeholder*placeholder); 


    }

Answer 1

来自http://mindprod.com/jgloss/round.html#MULTIPLE :

// rounding m up to next highest multiple of n
int ceil = ( m + n - 1 ) / n * n;

// rounding m down to multiple of n
int floor = m / n * n;

// rounding m to nearest multiple of n
int near = ( m + n/2 ) / n * n;

这里 m 是要舍入的数字，n 是您的“占位符”