在 java 中传递 bigdecimal 数字

Question

我想将值传递给使用大十进制数的方法，但我的程序显示编译器错误。

package com.khalidFarik;

import java.math.BigDecimal;

public class Main {
    public static void main(String[] args) {
        checknumbersinDecimals(12.3,12.2);
    }

    public static void checknumbersinDecimals(BigDecimal payment1,BigDecimal payment2){
        payment1 = new BigDecimal("1230.23");
        payment2 = new BigDecimal("1230.23");
        BigDecimal number3= payment1.subtract(payment2);
        System.out.println(number3.toString());
    }
}

如何在 main 方法中将大十进制数传递给我的方法 checknumbersinDecimals()？

Answer 1

将 BigDecimal 对象传递给方法类似于传递任何其他 Object 引用。创建一个新的 BigDecimal 对象并将其作为引用传递。您可以使用以下语法

checknumbersinDecimals(new BigDecimal(12.3),new BigDecimal(12.2));

12.3 表示 double 值。将其作为 new BigDecimal(12.3) 的构造函数值传递为其创建 BigDecimal 引用

Answer 2

您的方法接受 BigDecimal 作为参数，但您传递的是 12.3,12.2 - 这是 double 而不是 BigDecimal。

您将 BigDecimal 对象作为参数而不是 double 传递，如下所示：

checknumbersinDecimals(new BigDecimal(String.valueOf(12.3)),new BigDecimal(String.valueOf(12.2)));

注意: 使用BigDecimal(String) constructor instead of BigDecimal(double) constructor as by using the latter, you could lose precision. The caution as rightly mentioned in the doc:

The results of this constructor can be somewhat unpredictable. One might assume that writing new BigDecimal(0.1) in Java creates a BigDecimal which is exactly equal to 0.1 (an unscaled value of 1, with a scale of 1), but it is actually equal to 0.1000000000000000055511151231257827021181583404541015625. This is because 0.1 cannot be represented exactly as a double (or, for that matter, as a binary fraction of any finite length). Thus, the value that is being passed in to the constructor is not exactly equal to 0.1, appearances notwithstanding.

The String constructor, on the other hand, is perfectly predictable: writing new BigDecimal("0.1") creates a BigDecimal which is exactly equal to 0.1, as one would expect. Therefore, it is generally recommended that the String constructor be used in preference to this one.

When a double must be used as a source for a BigDecimal, note that this constructor provides an exact conversion; it does not give the same result as converting the double to a String using the Double.toString(double) method and then using the BigDecimal(String) constructor. To get that result, use the static valueOf(double) method.

Answer 3

BigDecimal.valueOf(double) 是建议使用而不是构造函数 new BigDecimal()，它会准确地为您提供传入的值。

checknumbersinDecimals(BigDecimal.valueOf(12.3), BigDecimal.valueOf(12.2));

在 java 中传递 bigdecimal 数字

pass bigdecimal numbers in java

java

bigdecimal