Java 安全字符串到 BigDecimal 的转换
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Safe String to BigDecimal conversion
提问by bezmax
I'm trying to read some BigDecimal values from the string. Let's say I have this String: "1,000,000,000.999999999999999" and I want to get a BigDecimal out of it. What is the way to do it?
我正在尝试从字符串中读取一些 BigDecimal 值。假设我有这个字符串：“1,000,000,000.999999999999999”，我想从中得到一个 BigDecimal。有什么方法可以做到？
First of all, I don't like the solutions using string replaces (replacing commas etc.). I think there should be some neat formatter to do that job for me.
首先，我不喜欢使用字符串替换（替换逗号等）的解决方案。我认为应该有一些整洁的格式化程序来为我完成这项工作。
I've found a DecimalFormatter class, however as it operates through double - huge amounts of precision are lost.
我找到了一个 DecimalFormatter 类，但是当它通过 double 运行时，会丢失大量的精度。
So, how can I do it?
那么，我该怎么做呢？
采纳答案by Jeroen Rosenberg
Check out setParseBigDecimalin DecimalFormat. With this setter, parsewill return a BigDecimal for you.
看看setParseBigDecimal在DecimalFormat的。使用此设置器，parse将为您返回一个 BigDecimal。
回答by jjnguy
Here is how I would do it:
这是我将如何做到的：
public String cleanDecimalString(String input, boolean americanFormat) {
if (americanFormat)
return input.replaceAll(",", "");
else
return input.replaceAll(".", "");
}
Obviously, if this were going in production code, it wouldn't be that simple.
显然，如果这在生产代码中进行，就不会那么简单了。
I see no issue with simply removing the commas from the String.
我认为简单地从字符串中删除逗号没有问题。
回答by Buhake Sindi
String value = "1,000,000,000.999999999999999";
BigDecimal money = new BigDecimal(value.replaceAll(",", ""));
System.out.println(money);
Full codeto prove that no NumberFormatExceptionis thrown:
证明没有NumberFormatException抛出的完整代码：
import java.math.BigDecimal;
public class Tester {
public static void main(String[] args) {
// TODO Auto-generated method stub
String value = "1,000,000,000.999999999999999";
BigDecimal money = new BigDecimal(value.replaceAll(",", ""));
System.out.println(money);
}
}
Output
输出
1000000000.999999999999999
1000000000.999999999999999
回答by Tim Pietzcker
resultString = subjectString.replaceAll("[^.\d]", "");
will remove all characters except digits and the dot from your string.
将从您的字符串中删除除数字和点以外的所有字符。
To make it locale-aware, you might want to use getDecimalSeparator()from java.text.DecimalFormatSymbols. I don't know Java, but it might look like this:
为了使其能够识别区域设置，您可能需要使用getDecimalSeparator()from java.text.DecimalFormatSymbols。我不懂 Java，但它可能看起来像这样：
sep = getDecimalSeparator()
resultString = subjectString.replaceAll("[^"+sep+"\d]", "");
回答by TofuBeer
The code could be cleaner, but this seems to do the trick for different locales.
代码可能更简洁，但这似乎适用于不同的语言环境。
import java.math.BigDecimal;
import java.text.DecimalFormatSymbols;
import java.util.Locale;
public class Main
{
public static void main(String[] args)
{
final BigDecimal numberA;
final BigDecimal numberB;
numberA = stringToBigDecimal("1,000,000,000.999999999999999", Locale.CANADA);
numberB = stringToBigDecimal("1.000.000.000,999999999999999", Locale.GERMANY);
System.out.println(numberA);
System.out.println(numberB);
}
private static BigDecimal stringToBigDecimal(final String formattedString,
final Locale locale)
{
final DecimalFormatSymbols symbols;
final char groupSeparatorChar;
final String groupSeparator;
final char decimalSeparatorChar;
final String decimalSeparator;
String fixedString;
final BigDecimal number;
symbols = new DecimalFormatSymbols(locale);
groupSeparatorChar = symbols.getGroupingSeparator();
decimalSeparatorChar = symbols.getDecimalSeparator();
if(groupSeparatorChar == '.')
{
groupSeparator = "\" + groupSeparatorChar;
}
else
{
groupSeparator = Character.toString(groupSeparatorChar);
}
if(decimalSeparatorChar == '.')
{
decimalSeparator = "\" + decimalSeparatorChar;
}
else
{
decimalSeparator = Character.toString(decimalSeparatorChar);
}
fixedString = formattedString.replaceAll(groupSeparator , "");
fixedString = fixedString.replaceAll(decimalSeparator , ".");
number = new BigDecimal(fixedString);
return (number);
}
}
回答by Ebith
The following sample code works well (locale need to be obtained dynamically)
下面的示例代码效果很好（需要动态获取locale）
import java.math.BigDecimal;
import java.text.NumberFormat;
import java.text.DecimalFormat;
import java.text.ParsePosition;
import java.util.Locale;
class TestBigDecimal {
public static void main(String[] args) {
String str = "0,00";
Locale in_ID = new Locale("in","ID");
//Locale in_ID = new Locale("en","US");
DecimalFormat nf = (DecimalFormat)NumberFormat.getInstance(in_ID);
nf.setParseBigDecimal(true);
BigDecimal bd = (BigDecimal)nf.parse(str, new ParsePosition(0));
System.out.println("bd value : " + bd);
}
}
回答by Lawrence
Old topic but maybe the easiest is to use Apache commons NumberUtils which has a method createBigDecimal (String value)....
老话题，但也许最简单的是使用 Apache commons NumberUtils，它有一个方法 createBigDecimal (String value)....
I guess (hope) it takes locales into account or else it would be rather useless.
我猜（希望）它考虑了语言环境，否则它会毫无用处。
回答by Rajkumar Teckraft
Please try this its working for me
请试试这个对我有用
BigDecimal bd ;
String value = "2000.00";
bd = new BigDecimal(value);
BigDecimal currency = bd;
回答by user3227576
I needed a solution to convert a String to a BigDecimal without knowing the locale and being locale-independent. I couldn't find any standard solution for this problem so i wrote my own helper method. May be it helps anybody else too:
我需要一个解决方案来将 String 转换为 BigDecimal 而不知道语言环境并且与语言环境无关。我找不到针对此问题的任何标准解决方案，因此我编写了自己的辅助方法。可能它也可以帮助其他人：
Update: Warning! This helper method works only for decimal numbers, so numbers which always have a decimal point! Otherwise the helper method could deliver a wrong result for numbers between 1000 and 999999 (plus/minus). Thanks to bezmax for his great input!
更新：警告！这个辅助方法只适用于十进制数，所以总是有小数点的数字！否则，辅助方法可能会为 1000 到 999999（加/减）之间的数字提供错误的结果。感谢 bezmax 的精彩投入！
static final String EMPTY = "";
static final String POINT = '.';
static final String COMMA = ',';
static final String POINT_AS_STRING = ".";
static final String COMMA_AS_STRING = ",";
/**
* Converts a String to a BigDecimal.
* if there is more than 1 '.', the points are interpreted as thousand-separator and will be removed for conversion
* if there is more than 1 ',', the commas are interpreted as thousand-separator and will be removed for conversion
* the last '.' or ',' will be interpreted as the separator for the decimal places
* () or - in front or in the end will be interpreted as negative number
*
* @param value
* @return The BigDecimal expression of the given string
*/
public static BigDecimal toBigDecimal(final String value) {
if (value != null){
boolean negativeNumber = false;
if (value.containts("(") && value.contains(")"))
negativeNumber = true;
if (value.endsWith("-") || value.startsWith("-"))
negativeNumber = true;
String parsedValue = value.replaceAll("[^0-9\,\.]", EMPTY);
if (negativeNumber)
parsedValue = "-" + parsedValue;
int lastPointPosition = parsedValue.lastIndexOf(POINT);
int lastCommaPosition = parsedValue.lastIndexOf(COMMA);
//handle '1423' case, just a simple number
if (lastPointPosition == -1 && lastCommaPosition == -1)
return new BigDecimal(parsedValue);
//handle '45.3' and '4.550.000' case, only points are in the given String
if (lastPointPosition > -1 && lastCommaPosition == -1){
int firstPointPosition = parsedValue.indexOf(POINT);
if (firstPointPosition != lastPointPosition)
return new BigDecimal(parsedValue.replace(POINT_AS_STRING, EMPTY));
else
return new BigDecimal(parsedValue);
}
//handle '45,3' and '4,550,000' case, only commas are in the given String
if (lastPointPosition == -1 && lastCommaPosition > -1){
int firstCommaPosition = parsedValue.indexOf(COMMA);
if (firstCommaPosition != lastCommaPosition)
return new BigDecimal(parsedValue.replace(COMMA_AS_STRING, EMPTY));
else
return new BigDecimal(parsedValue.replace(COMMA, POINT));
}
//handle '2.345,04' case, points are in front of commas
if (lastPointPosition < lastCommaPosition){
parsedValue = parsedValue.replace(POINT_AS_STRING, EMPTY);
return new BigDecimal(parsedValue.replace(COMMA, POINT));
}
//handle '2,345.04' case, commas are in front of points
if (lastCommaPosition < lastPointPosition){
parsedValue = parsedValue.replace(COMMA_AS_STRING, EMPTY);
return new BigDecimal(parsedValue);
}
throw new NumberFormatException("Unexpected number format. Cannot convert '" + value + "' to BigDecimal.");
}
return null;
}
Of course i've tested the method:
当然，我已经测试了该方法：
@Test(dataProvider = "testBigDecimals")
public void toBigDecimal_defaultLocaleTest(String stringValue, BigDecimal bigDecimalValue){
BigDecimal convertedBigDecimal = DecimalHelper.toBigDecimal(stringValue);
Assert.assertEquals(convertedBigDecimal, bigDecimalValue);
}
@DataProvider(name = "testBigDecimals")
public static Object[][] bigDecimalConvertionTestValues() {
return new Object[][] {
{"5", new BigDecimal(5)},
{"5,3", new BigDecimal("5.3")},
{"5.3", new BigDecimal("5.3")},
{"5.000,3", new BigDecimal("5000.3")},
{"5.000.000,3", new BigDecimal("5000000.3")},
{"5.000.000", new BigDecimal("5000000")},
{"5,000.3", new BigDecimal("5000.3")},
{"5,000,000.3", new BigDecimal("5000000.3")},
{"5,000,000", new BigDecimal("5000000")},
{"+5", new BigDecimal("5")},
{"+5,3", new BigDecimal("5.3")},
{"+5.3", new BigDecimal("5.3")},
{"+5.000,3", new BigDecimal("5000.3")},
{"+5.000.000,3", new BigDecimal("5000000.3")},
{"+5.000.000", new BigDecimal("5000000")},
{"+5,000.3", new BigDecimal("5000.3")},
{"+5,000,000.3", new BigDecimal("5000000.3")},
{"+5,000,000", new BigDecimal("5000000")},
{"-5", new BigDecimal("-5")},
{"-5,3", new BigDecimal("-5.3")},
{"-5.3", new BigDecimal("-5.3")},
{"-5.000,3", new BigDecimal("-5000.3")},
{"-5.000.000,3", new BigDecimal("-5000000.3")},
{"-5.000.000", new BigDecimal("-5000000")},
{"-5,000.3", new BigDecimal("-5000.3")},
{"-5,000,000.3", new BigDecimal("-5000000.3")},
{"-5,000,000", new BigDecimal("-5000000")},
{null, null}
};
}
