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”，我希望得到一个BigDecimal。这样做的方法是什么？
首先，我不喜欢使用字符串替换的解决方案（替换逗号等）。我认为应该有一些整洁的格式化程序为我做这项工作。
我找到了一个DecimalFormatter类，但是因为它运行的时间很长 - 会丢失大量的精度。
那么，我该怎么做呢？
答案 0 :(得分：88)
在DecimalFormat中查看setParseBigDecimal。使用此setter，parse将为您返回BigDecimal。
答案 1 :(得分：58)
String value = "1,000,000,000.999999999999999";
BigDecimal money = new BigDecimal(value.replaceAll(",", ""));
System.out.println(money);
完整代码，以证明不会抛出NumberFormatException：
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);
}
}
<强>输出
1000000000.999999999999999
答案 2 :(得分：19)
以下示例代码运行良好（需要动态获取区域设置）
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);
}
}
答案 3 :(得分：5)
代码可能更干净，但这似乎可以解决不同的语言环境。
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);
}
}
答案 4 :(得分：3)
我将如何做到这一点：
public String cleanDecimalString(String input, boolean americanFormat) {
if (americanFormat)
return input.replaceAll(",", "");
else
return input.replaceAll(".", "");
}
显然，如果这是在生产代码中，那就不那么简单了。
我认为从String中删除逗号没有任何问题。
答案 5 :(得分：3)
我需要一个解决方案来将String转换为BigDecimal，而不需要知道语言环境并且与语言环境无关。我无法找到解决此问题的任何标准解决方案，因此我编写了自己的帮助方法。也许它可以帮助其他人：
更新：警告！此辅助方法仅适用于十进制数，因此始终具有小数点的数字！否则，辅助方法可能会为1000到999999之间的数字（正/负）提供错误的结果。感谢bezmax的出色表现！
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;
}
当然，我已经测试了这种方法：
@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}
};
}
答案 6 :(得分：2)
resultString = subjectString.replaceAll("[^.\\d]", "");
将删除字符串中除数字和点之外的所有字符。
要使其能够识别区域设置，您可能需要使用getDecimalSeparator()中的java.text.DecimalFormatSymbols。我不懂Java，但它可能看起来像这样：
sep = getDecimalSeparator()
resultString = subjectString.replaceAll("[^"+sep+"\\d]", "");
答案 7 :(得分：1)
请试试这个为我工作
BigDecimal bd ;
String value = "2000.00";
bd = new BigDecimal(value);
BigDecimal currency = bd;
答案 8 :(得分：0)
旧主题但也许最简单的方法是使用Apache commons NumberUtils，它有一个方法createBigDecimal（String value）....
我猜（希望）它会考虑区域设置，否则它将毫无用处。