Question

我需要生成随机值并打印它们。

但它引发了一个异常：

 java.lang.NumberFormatException: For input string: "35,9"
    at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1241)
    at java.lang.Double.parseDouble(Double.java:540)
    at com.epam.lab.model.sweets.SweetsGenerator.paramFormatter(SweetsGenerator.java:71)
    at com.epam.lab.model.sweets.SweetsGenerator.next(SweetsGenerator.java:55)
    at com.epam.lab.model.NewYearGift.generate(NewYearGift.java:40)
    at com.epam.lab.controller.GiftController.generateGift(GiftController.java:86)
    at com.epam.lab.controller.GiftController.showGiftContent(GiftController.java:213)
    at com.epam.lab.view.Application.process(Application.java:89)
    at com.epam.lab.view.Application.estimateUserInput(Application.java:49)
    at com.epam.lab.view.Application.start(Application.java:43)
    at com.epam.lab.view.Main.main(Main.java:19)

只在这里发生：

public Sweets next() {      
    Sweets current = instances[rand.nextInt(instances.length)];
    double sugarParam = paramFormatter(randomSugarLevel(), PRECISION);
    double weightParam = paramFormatter(randomWeight(), PRECISION);

    try {
        return (Sweets) current.getClass()
                .getConstructor(double.class, double.class)
                .newInstance(sugarParam, weightParam);
        // Report programmer errors at run time:
    } catch (Exception e) {
        LOG.error("RuntimeException", e);
        throw new RuntimeException(e);
    }
}


private double paramFormatter(double sugarParam, DecimalFormat df) {
    return Double.parseDouble(df.format(sugarParam));
}


private double randomWeight() {
    return WEIGHT_MIN + (Math.random() * ((WEIGHT_MAX - WEIGHT_MIN) + 1));
}


private double randomSugarLevel() {
    return SUGAR_MIN + (Math.random() * ((SUGAR_MAX - SUGAR_MIN) + 1));
}

精确度是恒定的：

private static final DecimalFormat PRECISION = new DecimalFormat（“＃。＃”）;

但一切看起来还不错。

如何解决这个问题？

Answer 1

输入字符串包含,而不是.。将,替换为.以删除异常。理想情况下，输入应为35.9而不是35,9。

如果您使用,作为小数点分隔符，则可以使用DecimalFormatSymbols将,替换为小数点分隔符。

以下代码演示了DecimalFormatSymbols class：

的用法

DecimalFormat df = new DecimalFormat("#.#");
DecimalFormatSymbols dfs = DecimalFormatSymbols.getInstance();
dfs.setDecimalSeparator(',');
df.setDecimalFormatSymbols(dfs);
System.out.println(df.parse("35,9"));

以上代码打印35.9

数字格式异常 - 对于输入字符串：“35,9”

1 个答案: