java - 我想要做的是仅当数字在java中小数点后有超过5个零时，才将变量的 double 值转换为指数形式

Question

这是我转换输入值的函数 ->

private void frequencyUnitConverter(Utils.FrequencyUnit from, Utils.FrequencyUnit to, double input) {
        double constant = 1;
        switch (from) {
            case HERTZ:
                if (to == Utils.FrequencyUnit.KILOHERTZ) {
                    constant = 0.001;
                } else if (to == Utils.FrequencyUnit.MEGAHERTZ) {
                    constant = 1e-6;
                } else if (to == Utils.FrequencyUnit.GIGAHERTZ) {
                    constant = 1e-9;
                }
                break;
            case KILOHERTZ:
                if (to == Utils.FrequencyUnit.HERTZ) {
                    constant = 1000;
                } else if (to == Utils.FrequencyUnit.MEGAHERTZ) {
                    constant = 0.001;
                } else if (to == Utils.FrequencyUnit.GIGAHERTZ) {
                    constant = 1e-6;
                }
                break;
            case MEGAHERTZ:
                if (to == Utils.FrequencyUnit.HERTZ) {
                    constant = 1e+6;
                } else if (to == Utils.FrequencyUnit.KILOHERTZ) {
                    constant = 1000;
                } else if (to == Utils.FrequencyUnit.GIGAHERTZ) {
                    constant = 0.001;
                }
                break;
            case GIGAHERTZ:
                if (to == Utils.FrequencyUnit.HERTZ) {
                    constant = 1e+9;
                } else if (to == Utils.FrequencyUnit.KILOHERTZ) {
                    constant = 1e+6;
                } else if (to == Utils.FrequencyUnit.MEGAHERTZ) {
                    constant = 1000;
                }
                break;
        }

        double result = input * constant;
        binding.outputNumText.setText(String.valueOf(result).toLowerCase());
    }

目前我得到这样的东西 ->

此处结果应为 0.000123 格式，而不是 1.2299999999999998e-4 格式。
使用 double result = input * Constant; 计算结果后，如何将其转换为指数格式，并且仅在小数点后有 5 个零，否则以简单十进制打印结果格式。例如0.000123

Answer 1

它不会转换这个数字，而是显示这个数字，您可以在下面执行以下操作，

double noExpo = 1.2299999999999998e-4;

NumberFormat formatter = new DecimalFormat("#0.000000");
Log.e("number", ":::" + formatter.format(noExpo));

输出-->

数字:0.000123