检查字符串是否包含Java：Locale中的分数部分

Question

11
11.00
15,25 (for Locale like Denmark where the decimal part is denoted by a comma instead of dot)

我只想做一件事，当它是双倍的；即它包含一个分数值。分数值“00”也是有效的情况。

if(string contains fraction){
  // do something
}

给出了以上三个示例，对于11.00和15、25的控件应该在if内部，而对于11则不在。

我怎么查这个？

我有现场信息。这样我就知道字符串是否属于哪个区域设置了。既然如此，我怎么才能找到String是否有分数呢？

Answer 1

编辑：由于您已经编辑了说明您知道区域设置的问题，您可以将其与numberformat.getNumberInstance（Locale）.parse（strValue）结合使用，并使用逗号和千分隔符的正则表达式。这里有一个测试代码：

import java.text.DecimalFormatSymbols;
import java.text.NumberFormat;
import java.text.ParseException;
import java.util.Locale;

class Main{
  private static final Locale DUTCH = new Locale("nl","NL");

  public static void main(String[] a){
    test("11", Locale.ENGLISH);
    test("11", DUTCH);
    System.out.println();
    test("11.00", Locale.ENGLISH);
    test("11.00", DUTCH);
    System.out.println();
    test("11,00", Locale.ENGLISH);
    test("11,00", DUTCH);
    System.out.println();
    test("15.123", Locale.ENGLISH);
    test("15.123", DUTCH);
    System.out.println();
    test("15,123", Locale.ENGLISH);
    test("15,123", DUTCH);
    System.out.println();
    test("something", Locale.ENGLISH);
    test("something", DUTCH);
  }

  static void test(String val, Locale locale){
    try{
      DecimalFormatSymbols symbols = new DecimalFormatSymbols(locale);
      char decimalSep = symbols.getDecimalSeparator();
      char thousandSep = symbols.getGroupingSeparator();

      String escapedDecimalSep = decimalSep == '.' ? "\\." : decimalSep+"";
      String escapedThousandSep = thousandSep == '.' ? "\\." : thousandSep+"";

      String intRegex = "\\d+(" + escapedThousandSep + "\\d{3})*"; // Example ENGLISH: "\\d+(,\\d{3})*"
      String doubleRegex = intRegex + escapedDecimalSep + "\\d+"; // Example ENGLISH: "\\d+(,\\d{3})*\\.\\d+"

      NumberFormat format = NumberFormat.getInstance(locale);
      Number number = format.parse(val);
      if(val.matches(doubleRegex)){
        double d = number.doubleValue();
        System.out.println(val + " (in locale " + locale + ") is a double: " + d);
      } else if(val.matches(intRegex)){
        int i = number.intValue();
        System.out.println(val + " (in locale " + locale + ") is an integer: " + i);
      } else{
        System.out.println("Unable to determine whether value " + val + " is an integer or double for locale " + locale);
      }
    } catch(ParseException ex){
      System.out.println("Error occurred for value \"" + val + "\". Are you sure it's an integer or decimal?");
    }
  }
}

上网试试。

以下是输出：

11 (in locale en) is an integer: 11
11 (in locale nl_NL) is an integer: 11

11.00 (in locale en) is a double: 11.0
Unable to determine whether value 11.00 is an integer or double for locale nl_NL

Unable to determine whether value 11,00 is an integer or double for locale en
11,00 (in locale nl_NL) is a double: 11.0

15.123 (in locale en) is a double: 15.123
15.123 (in locale nl_NL) is an integer: 15123

15,123 (in locale en) is an integer: 15123
15,123 (in locale nl_NL) is a double: 15.123

Error occurred for value "something". Are you sure it's an integer or decimal?
Error occurred for value "something". Are you sure it's an integer or decimal?