java.lang.NumberFormatException：对于输入字符串：" null" [英] java.lang.NumberFormatException: For input string: "null"

问题描述

我正在解析文档但是我收到以下错误：

I'm parsing a doc and I get the following error:

Exception in thread "main" java.lang.NumberFormatException: For input string: "null"
    at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1222)
    at java.lang.Float.valueOf(Float.java:388)
    at CentroidGenerator$Centroid.averageLat(CentroidGenerator.java:403)
    at CentroidGenerator.getCentroids(CentroidGenerator.java:30)
    at CentroidGenerator.main(CentroidGenerator.java:139)

这是抛出异常的代码部分：

This is the part of code throwing the exception:

if (latitude!=null) {
    //if (!latitude.equals("null")) {
        String[] latValues = latitude.split(" ");
    float sum = 0;
    for (int i = 0; i < latValues.length; i++) {                
        sum = sum + Float.valueOf(latValues[i].trim()).floatValue();
    }
    latitude = Float.toString(sum / (float) latValues.length);
    //}
}   

如你所见，我试过检查null字符串，但即使取消注释第二个if语句，我也会得到相同的错误。

As you can see I've tried to check for "null" strings but even uncommenting the second if statement I get the same error.

谢谢

推荐答案

可能其中一个值为null（例如，字符串：123.4 null 5 null）不是第一个，所以我认为一个合适的解决方案是：

Maybe one of the values is "null" (for example, the string : "123.4 null 5 null") not the first one, so I think a proper solution will be:

String[] latValues = latitude.split(" ");
float sum = 0;
for (int i = 0; i < latValues.length; i++) {              
    if (!latValues[i].equals("null"))
        sum = sum + Float.valueOf(latValues[i].trim()).floatValue();
}
latitude = Float.toString(sum / (float) latValues.length);

或者在for循环中添加try-cath并忽略非数字的值。

or instead, add try-cath inside the for loop and ignore values that are not numbers.

编辑

正如评论（Sualeh）所指出的，最好使用试试/ catch因为今天明天它是null它是别的东西（即双倍空格......）。

As pointed in comments (Sualeh), it is better to use try / catch because today it's "null" tomorrow it's something else (i.e. double spaces...).

try {
sum = sum + Float.valueOf(latValues[i].trim()).floatValue();
}
catch (NumberFormatException e)
{
// log e if you want...
}

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