Java setText（）引发空指针异常，但元素不是空的

因此，我试图在HtmlUnit中设置元素的文本，但由于某些原因，我不太明白是否抛出了NullPointerException。显然，该元素存在于页面上，它是由htmlunit找到的！那么为什么setText会抛出错误呢？有什么想法吗

代码：

输出：

HtmlTextInput[<input type="text" required="" id="gc-redemption-input" name="claimCode" class="gc-redemption-input a-input-text a-span12 a-form-selected" autofocus="autofocus" value="">]

---

问题可能是

stringcode='123'

，因为它在我的IDE中显示以下错误：

未关闭的字符文字

。请尝试使用双引号：

stringcode=“123”
谢谢你的精彩捕捉！不幸的是，这不是问题所在，这是一行我没有抄过来，而是打出来的：）现在应该解决了。看见
HtmlTextInput[<input type="text" required="" id="gc-redemption-input" name="claimCode" class="gc-redemption-input a-input-text a-span12 a-form-selected" autofocus="autofocus" value="">]

Exception in thread "main" 
java.lang.NullPointerException
    at net.sourceforge.htmlunit.corejs.javascript.ScriptRuntime.hasTopCall(ScriptRuntime.java:3241)
    at net.sourceforge.htmlunit.corejs.javascript.InterpretedFunction.call(InterpretedFunction.java:102)
    at com.gargoylesoftware.htmlunit.javascript.host.dom.MutationObserver.attributeReplaced(MutationObserver.java:165)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.fireHtmlAttributeReplaced(HtmlElement.java:348)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.fireHtmlAttributeReplaced(HtmlElement.java:353)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.fireHtmlAttributeReplaced(HtmlElement.java:353)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.fireHtmlAttributeReplaced(HtmlElement.java:353)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.fireHtmlAttributeReplaced(HtmlElement.java:353)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.fireHtmlAttributeReplaced(HtmlElement.java:353)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.fireHtmlAttributeReplaced(HtmlElement.java:353)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.fireHtmlAttributeReplaced(HtmlElement.java:353)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.fireHtmlAttributeReplaced(HtmlElement.java:353)
    at com.gargoylesoftware.htmlunit.html.HtmlElement.setAttributeNS(HtmlElement.java:209)
    at com.gargoylesoftware.htmlunit.html.HtmlInput.setAttributeNS(HtmlInput.java:538)
    at com.gargoylesoftware.htmlunit.html.HtmlTextInput.setAttributeNS(HtmlTextInput.java:164)
    at com.gargoylesoftware.htmlunit.html.DomElement.setAttribute(DomElement.java:331)
    at com.gargoylesoftware.htmlunit.html.HtmlInput.setValueAttribute(HtmlInput.java:94)
    at com.gargoylesoftware.htmlunit.html.HtmlTextInput.setText(HtmlTextInput.java:124)