方法不会覆盖超类的方法

Question

public class MainActivity extends AppCompatActivity { 
    View mainView; 
    public static final MediaType FORM_DATA_TYPE = MediaType.parse("application/x-www-form-urlencoded; charset=utf-8"); 
    public static final String URL_FORM = "https://docs.google.com/forms/d/e/1FAIpQLSfjuEkX36zN1yycs7qCmnA-fqX7o8VNMEc3_xpNaBunPaVvhg/viewform"; 

    public static final String NAME_KEY = "entry.1874645379"; 
    public static final String FATHER_KEY = "entry.500977692"; 
    public static final String EMAIL_ID = "entry.325007106"; 
    public static final String CONTACT_NO = "entry.1124073934"; 
    public static final String WHATSAPP_NO = "entry.1503989573"; 
    public static final String ADHARCARD_NO = "entry.1176691600"; 

    public String Blood_group[] = {"O+", "O-", "A+", "A-", "B+", "B-", "AB+", "AB-"}, blood_group; 
    public String State[] = {"Andhra Pradesh", "Uttar Pradesh"}, state; 

    private Context context; 
    private EditText editName; 
    private EditText editEmail; 
    private EditText editContactNumber; 
    private EditText editFather; 
    private EditText whatsappno; 
    private EditText adharno; 
    private TextView select; 
    private RelativeLayout layout; 
    ArrayAdapter<String> Adapter; 

    @Nullable 
    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     mainView = inflater.inflate(R.layout.activity_main, container, false); 
     mainView.setTag("FOUR"); 

     context = mainView.getContext(); 
     Button SubmitButton = (Button)mainView. findViewById(R.id.button_register); 
     editName = (EditText)mainView. findViewById(R.id.editText_register_name); 
     editEmail = (EditText)mainView. findViewById(R.id.editText_register_email); 
     editContactNumber = (EditText)mainView. findViewById(R.id.editText_register_phone); 
     editFather = (EditText)mainView. findViewById(R.id.editText_register_college); 
     whatsappno=(EditText)mainView.findViewById(R.id.editText_register_college); 


    } 

    class PostDataTask extends AsyncTask<String, Void, Boolean> { 
     ProgressDialog progress; 
     @Override 
     protected void onPreExecute() { 
      progress = new ProgressDialog(context); 
      progress.setMessage("Please Wait.."); 
      progress.show(); 
     } 

     @Override 
     protected Boolean doInBackground(String... contactData) { 
      Boolean result = true; 
      String url = contactData[0]; 
      String name = contactData[1]; 
      String email = contactData[2]; 
      String number = contactData[3]; 
      String whatsappno = contactData[4]; 
      String editFather = contactData[5]; 
      String adharno = contactData[6]; 

      String postBody = ""; 

      try { 

       postBody = NAME_KEY + "=" + URLEncoder.encode(name, "UTF-8") + 
         "&" + EMAIL_ID + "=" + URLEncoder.encode(email, "UTF-8") + 
         "&" + CONTACT_NO + "=" + URLEncoder.encode(number, "UTF-8")+ 
         "&" + WHATSAPP_NO + "=" + URLEncoder.encode(whatsappno, "UTF-8")+ 
         "&" + FATHER_KEY + "=" + URLEncoder.encode(editFather, "UTF-8")+ 
         "&" + ADHARCARD_NO + "=" + URLEncoder.encode(adharno, "UTF-8"); 

      } catch (UnsupportedEncodingException ex) { 
       result = false; 
      } 
      try { 
       OkHttpClient client = new OkHttpClient(); 
       RequestBody body = RequestBody.create(FORM_DATA_TYPE, postBody); 
       Request request = new Request.Builder() 
         .url(url) 
         .post(body) 
         .build(); 
       Response response = client.newCall(request).execute(); 
      } catch (IOException exception) { 
       result = false; 
      } 
      return result; 
     } 

     @Override 
     protected void onPostExecute(Boolean result) { 
      progress.cancel(); 
      final AlertDialog.Builder alert=new AlertDialog.Builder(context); 
      alert.setMessage(result ? "Successfully Registered!" : "There was some error in sending message. Please try again after some time.").setCancelable(false).setPositiveButton("OK", new DialogInterface.OnClickListener() { 
       @Override 
       public void onClick(DialogInterface dialogInterface, int i) { 
        editName.setText(""); 
        editContactNumber.setText(""); 
        editEmail.setText(""); 
        editFather.setText(""); 
        whatsappno.setText(""); 
        adharno.setText(""); 



       } 
      }); 
      AlertDialog alertDialog=alert.create(); 
      alertDialog.show(); 
     } 
    } 

    boolean validData() 
    { String userName=editName.getText().toString(); 
     String userContactNumber = editContactNumber.getText().toString(); 
     String userEmail = editEmail.getText().toString(); 
     String userFather=editFather.getText().toString(); 
     String whatsapp= whatsappno.getText().toString(); 
     String adhar=adharno.getText().toString(); 

     if (userName.length()<3) 
     { 
      Toast.makeText(context, "Enter a Valid Name", Toast.LENGTH_SHORT).show(); 
      return false; 
     } 
     if (userContactNumber.length()!=10||userContactNumber.startsWith("0")||userContactNumber.startsWith("1")||userContactNumber.startsWith("2")||userContactNumber.startsWith("3")||userContactNumber.startsWith("4")||userContactNumber.startsWith("5")||userContactNumber.startsWith("6")) 
     { 
      Toast.makeText(context, "Enter a Valid Number", Toast.LENGTH_SHORT).show(); 
      return false; 
     } 
     if (userEmail.length()<3) 
     { 
      Toast.makeText(context, "Enter a Valid Email Address", Toast.LENGTH_SHORT).show(); 
      return false; 
     } 
     if (userFather.length()<3) 
     { 
      Toast.makeText(context, "Enter a Valid Name", Toast.LENGTH_SHORT).show(); 
      return false; 
     } 
     if(whatsapp.length()!=10|| whatsapp.startsWith("0")||whatsapp.startsWith("1")||whatsapp.startsWith("2")||whatsapp.startsWith("3")||whatsapp.startsWith("4")||whatsapp.startsWith("5")||whatsapp.startsWith("6")) 
     { 
      Toast.makeText(context, "Enter a Valid Number", Toast.LENGTH_SHORT).show(); 
      return false; 
     } 
     if (adhar.length()!=12) 
     { 
      Toast.makeText(context,"Enter the Valid Adhar Number",Toast.LENGTH_SHORT).show(); 
     } 
     return true; 
    } 
} 

Answer 1

这是因为它是AppCompatActivity的重写方法，它是片段的重写方法。

改变这种方法

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 

} 

要

@Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     context =this; 
     Button SubmitButton = (Button) findViewById(R.id.button_register); 
     editName = (EditText)findViewById(R.id.editText_register_name); 
     editEmail = (EditText) findViewById(R.id.editText_register_email); 
     editContactNumber = (EditText) findViewById(R.id.editText_register_phone); 
     editFather = (EditText) findViewById(R.id.editText_register_college); 
     whatsappno=(EditText)findViewById(R.id.editText_register_college); 
}