Java.lang.NumberFormatException 错误:空字符串 - 汇率应用程序

2022-01-10 00:00:00 xml parsing xml-parsing netbeans java

我正在编写一个程序，它从 http://www 获取每日汇率.tcmb.gov.tr/kurlar/today.xml 并将它们保存到列表中.这是我的代码:

I'm writing a program which gets daily exchange rates from http://www.tcmb.gov.tr/kurlar/today.xml and saves them to the List. Here is my code: 

public class ParseTheXml {

    private List<CurrencyPojo> currencyList;


    public void setCurrencyList(List<CurrencyPojo> currencyList) {
        this.currencyList = currencyList;
    }

    public List<CurrencyPojo> getCurrencyList() throws ParserConfigurationException {
        currencyList = new ArrayList<CurrencyPojo>();

        try {
            DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
            URL url = new URL("http://www.tcmb.gov.tr/kurlar/today.xml");
            Document document = builder.parse(url.openStream());

            NodeList nodeList = document.getElementsByTagName("Currency");

            for (int i = 0; i < nodeList.getLength(); i++) { // döngü her currency türü için
                Element element = (Element) nodeList.item(i);
                CurrencyPojo currencyPojoObject = new CurrencyPojo(); 

                currencyPojoObject.setCrossOrder(Integer.parseInt(element.getAttribute("CrossOrder")));
                currencyPojoObject.setKod(element.getAttribute("Kod"));
                currencyPojoObject.setCurrenyCode(element.getAttribute("CurrencyCode"));

                currencyPojoObject.setUnit(Integer.parseInt(element.getElementsByTagName("Unit").item(0).getTextContent()));
                currencyPojoObject.setIsim(element.getElementsByTagName("Isim").item(0).getTextContent());
                currencyPojoObject.setCurrencyName(element.getElementsByTagName("CurrencyName").item(0).getTextContent());
                currencyPojoObject.setForexBuying(Double.parseDouble(element.getElementsByTagName("ForexBuying").item(0).getTextContent()));


       currencyPojoObject.setForexSelling(Double.parseDouble(element.getElementsByTagName("ForexSelling").item(0).getTextContent()));  //  Last 3 codes have Emppty String errors
                currencyPojoObject.setBanknoteBuying(Double.parseDouble(element.getElementsByTagName("BanknoteBuying").item(0).getTextContent()));
                currencyPojoObject.setBanknoteSelling(Double.parseDouble(element.getElementsByTagName("BanknoteSelling").item(0).getTextContent()));

                currencyList.add(currencyPojoObject);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        return currencyList;
    }

在获得 ForexSelling、BanknoteBuying 和 Banknote Selling 值的部分，我得到了

On the part that getting ForexSelling, BanknoteBuying and Banknote Selling values,I get

java.lang.NumberFormatException: empty String
at sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1842)
    at sun.misc.FloatingDecimal.parseDouble(FloatingDecimal.java:110)
    at java.lang.Double.parseDouble(Double.java:538)
    at javaxmlparseandshow.ParseTheXml.getCurrencyList(ParseTheXml.java:55)
    at javaxmlparseandshow.ParseTheXml.main(ParseTheXml.java:75)

有人可以帮我解决这些问题吗?提前致谢.

Can someone help me to fix these? Thanks in advance.

推荐答案

或者你可以设置0为空的xml字符串

Alternatively you can set 0 to empty xml strings 

private double parseDouble(String val){
    if(val== null || val.isEmpty()) 
        return 0.0;
    else
        return Double.parseDouble(val);
}

前:

currencyPojoObject.setForexSelling(parseDouble(element.getElementsByTagName("ForexSelling").item(0).getTextContent()));

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