Question

当我尝试将字符串转换为double时，我正在使用NumberFormatException。似乎我有正确的方法去做，但异常仍然出现。这真的让我很生气，因为我上周一直在努力。这是我正在尝试做的事情：

String csvFile="N:/Downloads/Chrome Downloads/GeoIPCountryWhois.csv";
BufferedReader br=null;
String line="";
String cvspl=",";
    try{
        for(int i=0;i<5000;i++)
        {
        //System.out.println("I'm here in retriving IP");
        br=new BufferedReader(new FileReader(csvFile));
        while ((line=br.readLine())!=null){
            String[] country=line.split(cvspl);
            l.add(country[0]);
            double a = Double.parseDouble(country[2]);
            double b = Double.parseDouble(country[3]);
            IpParameters p = new IpParameters(a, b);
            IP.put(country[0], p);

        }           
        }


    }catch(FileNotFoundException e){

        e.printStackTrace();

    }catch (IOException e){
        e.printStackTrace();
    }finally{
        if (br !=null){
            try{
                br.close();
            }catch (IOException e){
                e.printStackTrace();
            }
        }
    }

} }

我正在成功检索文件中的数字。当我打印国家[2]时，它显示存储在该索引中的值。

Answer 1

我找到了这个文件https://raw.githubusercontent.com/alecthomas/geoip/master/GeoIPCountryWhois.csv （如果它与您的工作文件类似）并使用以下两行进行测试：

"1.0.0.0","1.0.0.255","16777216","16777471","AU","Australia"
"1.0.1.0","1.0.3.255","16777472","16778239","CN","China"

并且错误是

Exception in thread "main" java.lang.NumberFormatException: For input string: ""16777216""
    at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:2043)
    at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
    at java.lang.Double.parseDouble(Double.java:538)
    at Test.main(Test.java:22)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)

我的代码有效：

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.StringReader;

/**
 * Created by mojtab23 on 8/1/16.
 */
public class Test {
    public static void main(String[] args) {
        BufferedReader br = null;
        String line = "";
        String cvspl = ",";
        try {

            //System.out.println("I'm here in retriving IP");
            br = new BufferedReader(new StringReader("\"1.0.0.0\",\"1.0.0.255\",\"16777216\",\"16777471\",\"AU\",\"Australia\"\n" +
                    "\"1.0.1.0\",\"1.0.3.255\",\"16777472\",\"16778239\",\"CN\",\"China\""));
            while ((line = br.readLine()) != null) {
                String[] country = line.split(cvspl);
//                    l.add(country[0]);
                double a = Double.parseDouble(country[2].replaceAll("\"", ""));
                double b = Double.parseDouble(country[3].replaceAll("\"", ""));
//                    IpParameters p = new IpParameters(a, b);
                System.out.println("IP: " + country[0]);
                System.out.println(a + " ," + b);


            }


        } catch (FileNotFoundException e) {

            e.printStackTrace();

        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

}

使用DoubleParse无法将字符串转换为double

1 个答案: