Android 登录验证失败

我正在使用ksoap web服务进行用户登录。。但当我添加用户名和密码，然后得到消息登录失败…我如何解决它。。username=adc和password=adc已在web服务中存储

主课

public class DotNetWSActivity extends Activity {
static boolean errored = false;
Button b;
TextView tv;
EditText et ,pw;
boolean loginStatus;
ProgressBar pg;
String UserName ,Password;
String LoginAuthentication;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    //Name Text control
    et = (EditText) findViewById(R.id.editText1);
    pw = (EditText) findViewById(R.id.editText2);
    //Display Text control
    tv = (TextView) findViewById(R.id.tv_result);
    //Button to trigger web service invocation
    b = (Button) findViewById(R.id.button1);
    //Display progress bar until web service invocation completes
    pg = (ProgressBar) findViewById(R.id.progressBar1);
    //Button Click Listener
    b.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            //Check if Name text control is not empty
            if (et.getText().length() != 0 && et.getText().toString() != "") {
                 if (pw.getText().length() != 0 && pw.getText().toString() != "") {
                //Get the text control value
                UserName = et.getText().toString();
                Password =pw.getText().toString();
                //Create instance for AsyncCallWS
                AsyncCallWS task = new AsyncCallWS();
                //Call execute 
                task.execute();
            //If text control is empty
            } else {
                tv.setText("Please enter name");
            }
            }else {
                  tv.setText("Please enter password");
            }
        }
    });
}

private class AsyncCallWS extends AsyncTask<String, Void, Void> {
    @Override
    protected Void doInBackground(String... params) {
        LoginAuthentication = WebService.invokeHelloWorldWS(UserName, Password,"LoginAuthentication");
        return null;
    }

    protected void onPostExecute(Void result) {
//      webservicePG.setVisibility(View.INVISIBLE);
        Intent intObj = new Intent(DotNetWSActivity.this,dfdf.class);
        //Error status is false
        if(!errored){
            //Based on Boolean value returned from WebService
            if(loginStatus){
                //Navigate to Home Screen
                startActivity(intObj);
            }else{
                //Set Error message
                tv.setText("Login Failed, try again");
            }
        //Error status is true   
        }else{
            tv.setText("Error occured in invoking webservice");
        }
        //Re-initialize Error Status to False
        errored = false;
    }

    protected void onPreExecute() {
        pg.setVisibility(View.VISIBLE);
    }


    protected void onProgressUpdate(Void... values) {
    }

}

}

日志：

07-24 12:13:47.121: W/System.err(1593): java.lang.NullPointerException
07-24 12:13:47.121: W/System.err(1593):     at   com.prgguru.android.WebService.invokeHelloWorldWS(WebService.java:50)
07-24 12:13:47.141: W/System.err(1593):     at com.prgguru.android.DotNetWSActivity$AsyncCallWS.doInBackground(DotNetWSActivity.java:63)
07-24 12:13:47.151: W/System.err(1593):     at com.prgguru.android.DotNetWSActivity$AsyncCallWS.doInBackground(DotNetWSActivity.java:1)
07-24 12:13:47.151: W/System.err(1593):     at android.os.AsyncTask$2.call(AsyncTask.java:264)
07-24 12:13:47.151: W/System.err(1593):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
07-24 12:13:47.151: W/System.err(1593):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
07-24 12:13:47.151: W/System.err(1593):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
07-24 12:13:47.151: W/System.err(1593):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
07-24 12:13:47.162: W/System.err(1593):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
07-24 12:13:47.162: W/System.err(1593):     at java.lang.Thread.run(Thread.java:856)

有几件事

在你的后台

LoginAuthentication = WebService.invokeHelloWorldWS(UserName, Password,"LoginAuthentication");

您正在从尚未实例化的类调用方法。我建议在WebService中创建一个构造函数，并接受这3个参数，然后在类中使用getter返回resTxt。那么你给班级打电话的样子

WebService webservice = new WebService(UserName, Password,"LoginAuthentication");
String  LoginAuthentication = webservice.getResTxt(); 

或者，如果您坚持保持当前的格式，您仍然必须首先调用新的WebService来实例化该类

您现在没有收到编译错误的唯一原因是因为您的invokeHelloWorldWS方法是静态的。。。就我所知，没有理由认为它是静态的

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另外，您正在将NULL从doInBackground传递到onPostExecute。。。为什么？onPostExecute的要点是从doInBackground获取值并对其进行处理

哪一行是WebService.java:50？在WebService类中，您得到用户名和密码值了吗？首先检查。是的，我在webservice中获得了价值class@Jens意思是我不明白？？？@user3871733你在你班的第50行得到一个NPE。我要知道的是Webservice类中的第50行是什么？

WebService webservice = new WebService(UserName, Password,"LoginAuthentication");
String  LoginAuthentication = webservice.getResTxt();