java - 乘以两位小数 - Java

Question

将 double 类型的数字相乘，输出结果需要保留两位小数

double creditCardPercentage = 0.03;
String renewalEventAmount = "2144.60";
double expectedRenewalAmount = 0;
expectedRenewalAmount = Double.parseDouble(renewalEventAmount) * creditCardPercentage;

expectedRenewalAmount 的输出是 64.338，那么我们如何将上面的输出格式化为两位小数

预期:

64.33

Answer 1

您应该使用 BigDecimal 类，因为它具有浮点精度的内置处理:

BigDecimal creditCardPercentage = new BigDecimal(0.03);
String renewalEventAmountString = "2144.60";
BigDecimal renewalEventAmount = new BigDecimal(renewalEventAmountString);
BigDecimal expectedRenewalAmount = renewalEventAmount.multiply(creditCardPercentage);
expectedRenewalAmount = expectedRenewalAmount.setScale(2, BigDecimal.ROUND_HALF_DOWN);

System.out.println(expectedRenewalAmount); // prints 64.33

使用 BigDecimal 处理格式的优点之一是，它允许您将代码与业务逻辑分开，即从输出的 View 代码中四舍五入到小数点后两位结果给用户。