android - 解析在android中的异步任务中给出错误

Question

请遵循代码，我不明白为什么它不加载数据。下面的 Activity 是在 splash Activity 之后开始的，在这里我试图从服务器下载数据并解析它并尝试将它附加到微调器但是它强制关闭应用程序说在第 1 行找不到元素所以我不明白为什么它不起作用。 ..

已编辑:--- 代码适用于 android 2.3 及更高版本，但不适用于 android 2.2 所需的最低 sdk 版本为 8 (Android 2.2)

public class Registration extends Activity{

private List<RegisterMessage> regis_msg;
private List<CountryMessage> country_msg;
ArrayList<String> countryName,countryCode,isoCode,countryFlag;
EditText fname,sname,email,mobileno;
Spinner country;
AppPreferences ap;
Button btnregister;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.registration);

    country = (Spinner)findViewById(R.id.country);
    fname = (EditText)findViewById(R.id.fname);
    sname  = (EditText)findViewById(R.id.sname);
    email = (EditText)findViewById(R.id.email);
    mobileno = (EditText)findViewById(R.id.mobileno);

    ap = new AppPreferences(getApplicationContext());

//  mobileno.setText(ap.getPreferences("MobileNo"));

    btnregister = (Button)findViewById(R.id.btnregister);

    btnregister.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                if(fname.getText().toString().equals("")){
                    Toast.makeText(getApplicationContext(), "Please Enter Firstname.", Toast.LENGTH_SHORT).show();
                    fname.setFocusable(true);
                    fname.requestFocus();
                }else if (sname.getText().toString().equals("")){
                    Toast.makeText(getApplicationContext(), "Please Enter Surname.", Toast.LENGTH_SHORT).show();
                    sname.setFocusable(true);
                    sname.requestFocus();
                }else if (email.getText().toString().equals("")){
                    Toast.makeText(getApplicationContext(), "Please Enter Email address.", Toast.LENGTH_SHORT).show();
                    email.setFocusable(true);
                    email.requestFocus();
                }else if (mobileno.getText().toString().equals("")){
                    Toast.makeText(getApplicationContext(), "Please Enter Mobile No.", Toast.LENGTH_SHORT).show();
                    email.setFocusable(true);
                    email.requestFocus();
                }else{
                    new RegistrationTry().execute();
                }
            }
      });

    if(!isOnline()) {
        Log.v("isOnline",isOnline()+"");
        Toast.makeText(getApplicationContext(), "You device is not connected to the internet.",Toast.LENGTH_LONG).show();
    }else{
        new CountryData().execute();
    }

}

public boolean isOnline(){
    ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    boolean isconnected;
    if (netInfo==null || !netInfo.isConnected())
    isconnected=false;
    else
    isconnected=true;
    Log.v("isOnliNe",isconnected+"");
    return isconnected;
}   

class CountryData extends AsyncTask<Object, Object, Object> {
   // private CustomizeDialog Dialog = new CustomizeDialog(Registration.this);
    private ProgressDialog Dialog = new ProgressDialog(Registration.this);
    @Override
    protected void onPreExecute() {
        Dialog.setMessage("Loading please wait........");
        Dialog.show();
    }

    protected Void doInBackground(Object...params) {
        try{
            String url= newsReaderUrls.BASE_URL + newsReaderUrls.COUNTRY_URL;
            Log.v("URL",url);
            BaseFeedParser parser  =  new BaseFeedParser(url);
            country_msg = parser.CountryParse();
            countryName = new ArrayList<String>();
            countryCode = new ArrayList<String>();
            isoCode = new ArrayList<String>();
            countryFlag = new ArrayList<String>();
            countryName.add(0, "Select");
            for (CountryMessage msg : country_msg){
                 countryName.add(msg.getCountryName());
                 countryCode.add(msg.getCountryCode());
                 isoCode.add(msg.getIsoCode());
                 countryFlag.add(msg.getCountryFlag());
            }
        } catch (Throwable t){
            Log.e("AndroidNews",t.getMessage(),t);
        }
        return null;
    }

     protected void onProgressUpdate(Object... values){
        // TODO Auto-generated method stub
        super.onProgressUpdate(values);
     }

    @Override
    protected void onPostExecute(Object result) {
        if(Dialog.isShowing()){
            Dialog.dismiss();
        }
        String[] array_spinner = countryName.toArray(new String[countryName.size()]);
        ArrayAdapter<String> adapter = new ArrayAdapter<String> (getApplicationContext(),android.R.layout.simple_spinner_item,array_spinner);
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        country.setAdapter(adapter);
        String cn = ap.getPreferences("CountryIso");
        if(!cn.equals("")){
            int index = isoCode.indexOf(cn);
            country.setSelection(index+1);
        }else if(countryName.indexOf("Nigeria") !=  -1){
            country.setSelection(countryName.indexOf("Nigeria")+1);
        }
    }
}

class RegistrationTry extends AsyncTask<Void, Void, Void> {
   // private CustomizeDialog Dialog = new CustomizeDialog(Registration.this);
    private ProgressDialog Dialog = new ProgressDialog(Registration.this);
    int foreward;
    @Override
    protected void onPreExecute() {
        Dialog.setMessage("Loading please wait........");
        Dialog.show();
    }

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


    protected Void doInBackground(Void...params) {
        try{
            String defaultC_code="ng";
            /*if(countryName.size()<0){
                defaultC_code = "ng";
            }else{
                int index = country.getSelectedItemPosition();
                defaultC_code = isoCode.get(index-1);
            }*/
            ap.savePreferences("MobileNo", mobileno.getText().toString());
            String url= newsReaderUrls.BASE_URL + newsReaderUrls.REGISTER_URL + "Mobile="+ mobileno.getText().toString()+
                        "&First_Name="+fname.getText().toString()+"&Last_Name="+sname.getText().toString()+
                        "&Email="+email.getText().toString()+"&Device_Type=Phone&Device_Platform=Android"+
                        "&ISO_Code=" + defaultC_code;
            Log.v("Login", url);
            BaseFeedParser parser = new BaseFeedParser(url);
            regis_msg = parser.RegisterParse();

            for (RegisterMessage msg : regis_msg){
                Log.v("Status", msg.getStatus());
                foreward = Integer.parseInt(msg.getStatus());
            }

        } catch (Throwable t){
            Log.e("AndroidNews",t.getMessage(),t);
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        if(foreward == 2 || foreward == 3){
            ap.savePreferences("Registered", "yes");
            Intent i = new Intent(Registration.this,DashBoard.class);
            startActivity(i);
            finish();
        }else{
            Toast.makeText(getBaseContext(), "Registration failed please try later.", Toast.LENGTH_SHORT).show();
        }
        if(Dialog.isShowing()){
            Dialog.dismiss();
        }
    }
}

}

日志猫

10-31 16:13:41.022: ERROR/AndroidNews(599): org.apache.harmony.xml.ExpatParser$ParseException: At line 1, column 0: no element found
10-31 16:13:41.022: ERROR/AndroidNews(599): java.lang.RuntimeException: org.apache.harmony.xml.ExpatParser$ParseException: At line 1, column 0: no element found
10-31 16:13:41.022: ERROR/AndroidNews(599):     at com.websoft.android.parser.BaseFeedParser.CountryParse(BaseFeedParser.java:189)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at com.websoft.android.newsreel.Registration$CountryData.doInBackground(Registration.java:117)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at com.websoft.android.newsreel.Registration$CountryData.doInBackground(Registration.java:1)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at android.os.AsyncTask$2.call(AsyncTask.java:185)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at java.util.concurrent.FutureTask.run(FutureTask.java:137)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1068)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:561)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at java.lang.Thread.run(Thread.java:1096)
10-31 16:13:41.022: ERROR/AndroidNews(599): Caused by: org.apache.harmony.xml.ExpatParser$ParseException: At line 1, column 0: no element found
10-31 16:13:41.022: ERROR/AndroidNews(599):     at org.apache.harmony.xml.ExpatParser.finish(ExpatParser.java:553)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at org.apache.harmony.xml.ExpatParser.parseDocument(ExpatParser.java:483)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at org.apache.harmony.xml.ExpatReader.parse(ExpatReader.java:320)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at org.apache.harmony.xml.ExpatReader.parse(ExpatReader.java:277)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at android.util.Xml.parse(Xml.java:87)
10-31 16:13:41.022: ERROR/AndroidNews(599):     at com.websoft.android.parser.BaseFeedParser.CountryParse(BaseFeedParser.java:187)
10-31 16:13:41.022: ERROR/AndroidNews(599):     ... 8 more
10-31 16:13:41.022: DEBUG/AndroidRuntime(599): Shutting down VM
10-31 16:13:41.042: WARN/dalvikvm(599): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
10-31 16:13:41.042: ERROR/AndroidRuntime(599): FATAL EXCEPTION: main
10-31 16:13:41.042: ERROR/AndroidRuntime(599): java.lang.NullPointerException
10-31 16:13:41.042: ERROR/AndroidRuntime(599):     at com.websoft.android.newsreel.Registration$CountryData.onPostExecute(Registration.java:140)
10-31 16:13:41.042: ERROR/AndroidRuntime(599):     at android.os.AsyncTask.finish(AsyncTask.java:417)
10-31 16:13:41.042: ERROR/AndroidRuntime(599):     at android.os.AsyncTask.access$300(AsyncTask.java:127)
10-31 16:13:41.042: ERROR/AndroidRuntime(599):     at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429)
10-31 16:13:41.042: ERROR/AndroidRuntime(599):     at android.os.Handler.dispatchMessage(Handler.java:99)
10-31 16:13:41.042: ERROR/AndroidRuntime(599):     at android.os.Looper.loop(Looper.java:123)
10-31 16:13:41.042: ERROR/AndroidRuntime(599):     at android.app.ActivityThread.main(ActivityThread.java:4627)
10-31 16:13:41.042: ERROR/AndroidRuntime(599):     at java.lang.reflect.Method.invokeNative(Native Method)
10-31 16:13:41.042: ERROR/AndroidRuntime(599):     at java.lang.reflect.Method.invoke(Method.java:521)
10-31 16:13:41.042: ERROR/AndroidRuntime(599):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
10-31 16:13:41.042: ERROR/AndroidRuntime(599):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
10-31 16:13:41.042: ERROR/AndroidRuntime(599):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

当您在执行 country_msg = parser.CountryParse(); 时出现解析异常 ExpatParser$ParseException 。

At line 1, column 0: no element found

这意味着文件是空的。

因此 countryName , countryCode , isoCode 都是 null ，因此 CountryData 的 postExecute() 中的 NPE >。

查看此字符串 newsReaderUrls.BASE_URL + newsReaderUrls.COUNTRY_URL 放入浏览器时是否返回有效的 URL 和正确的 xml