Java中的parseDouble导致NumberFormatException [英] parseDouble in Java results to NumberFormatException
问题描述
我正在尝试从属性文件加载信息，我有以下代码：
I am trying to load info from a properties file and i have the following code:
anInt = Integer.parseInt(prop.getProperty("anInt"));
aDouble = Double.parseDouble(prop.getProperty("aDouble"));
虽然第一行工作正常，但第二行我尝试
到加载一个double变量会抛出一个 NumberFormatException 。具体的异常消息是：
and while the first line works just fine, the second one where i am trying
to load a double variable throws a NumberFormatException. The specific exception message is:
Exception in thread "main" java.lang.NumberFormatException: For input string: "78,5"
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1222)
at java.lang.Double.parseDouble(Double.java:510)
at Assignment1.BaseStation.readPropertyFile(BaseStation.java:59)
at Assignment1.BaseStation.main(BaseStation.java:83)
推荐答案
如果要使用 Double.parseDouble（）进行解析，则必须使用句点作为分隔符，而不是逗号。它在Double类的文档中说
You have to use a period as a delimiter, not comma if you want to parse using Double.parseDouble(). It says in documentation for the Double class that
FloatingPointLiteral ... [is]在Java的词汇结构部分中定义语言规范。
FloatingPointLiteral ... [is] as defined in the lexical structure sections of the of the Java Language Specification.
来自Java语言规范：
From Java Language Specification:
FloatingPointLiteral：
FloatingPointLiteral:
- 数字。数字选择 ExponentPart 选择 FloatTypeSuffix 选择
- 。 Digits ExponentPart opt FloatTypeSuffix opt
- Digits ExponentPart FloatTypeSuffix opt
- Digits ExponentPart opt FloatTypeSuffix
- Digits . Digits opt ExponentPart opt FloatTypeSuffix opt
- . Digits ExponentPart opt FloatTypeSuffix opt
- Digits ExponentPart FloatTypeSuffix opt
- Digits ExponentPart opt FloatTypeSuffix
如果你想采用语言环境考虑到，您可以使用 java.text.NumberFormat ：
If you want to take locale into consideration, you can use java.text.NumberFormat:
NumberFormat nf = NumberFormat.getInstance();
double number = nf.parse(myString).doubleValue();
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