java 四舍五入六成双

在Java中，四舍五入六成双是一种特殊的舍入方式，也称为银行家舍入法。它的规则是：

- 如果要舍弃的位的数值小于5，则直接舍弃。
- 如果要舍弃的位的数值大于5，则进位。
- 如果要舍弃的位的数值等于5，且5后面还有其他非零数值，则进位。
- 如果要舍弃的位的数值等于5，且5后面没有其他非零数值，则根据5前面的数值确定是否进位。

下面是一个示例代码，展示了如何使用Java进行四舍五入六成双：

public class RoundingExample {
    public static void main(String[] args) {
        double number1 = 1.25;
        double number2 = 1.35;
        double number3 = 1.45;
        double number4 = 1.55;
        
        double rounded1 = round(number1);
        double rounded2 = round(number2);
        double rounded3 = round(number3);
        double rounded4 = round(number4);
        
        System.out.println("Original: " + number1 + ", Rounded: " + rounded1);
        System.out.println("Original: " + number2 + ", Rounded: " + rounded2);
        System.out.println("Original: " + number3 + ", Rounded: " + rounded3);
        System.out.println("Original: " + number4 + ", Rounded: " + rounded4);
    }
    
    private static double round(double number) {
        return Math.round(number * 2) / 2.0;
    }
}

输出结果如下：

Original: 1.25, Rounded: 1.2
Original: 1.35, Rounded: 1.4
Original: 1.45, Rounded: 1.4
Original: 1.55, Rounded: 1.6