从命令提示符处执行时，对Web元素的操作不起作用

Question

我在日志文件中没有得到任何错误来解决该问题。该代码将输入到homepage.java中，并以login方法开头，但是txtusername不会填充这些值。在日食中工作正常。从命令行执行时会发生这种情况

D:\Workspaces\test> java -cp 
  "D:\Workspaces\test\bin;D:\Workspaces\test\lib\*;C:\Users\me\plugins\*" 
  org.testng.TestNG D:\Workspaces\test\testng1.xml

public class TestMain extends DriverInstance {
    HomePage homePage;
    WebDriver driver;

    @BeforeMethod
    public void launchAppication()  {
        driver = launchBrowser();
        launchURL();
        homePage = PageFactory.initElements(driver, HomePage.class);
    }

    @Test(groups = { "functest", "Login" }, testName = "RTSFS-21: Verify Login with Correct username and correct Password", priority = 1)
    public void verifyLogin_CorrectLoginCredentials() {     
        try {
            System.out.println("hello this is test method after try block");
            //Thread.sleep(5000);
            homePage.login(driver, "Login");
            System.out.println("hello this is test method after login method");
            // homePage.pageWait();
            //Thread.sleep(5000);
            homePage.validateURL("www.xyz.com", "Verify Login with Correct username and correct Password");
        } catch (Exception e) {
            log.fail("exception : " + e.getMessage());
        }
    }
}

这是homepage.java

public void login(WebDriver driver, String elementName) 
{       
    JsonReader jr = new JsonReader();

    try
    {
        System.out.println("hello this is login block");
        txtUsername.sendKeys(jr.GetElementValue(elementName+".Username"));
        System.out.println("hello this is text username");
    }

执行将显示消息“您好，这是登录阻止”，并突然结束。