Android AsyncTask运行时错误

Question

我开发了一个购物应用。我正在使用网络服务来获取物品。我在asynctask中调用web服务函数，我成功获取了项目。但是我添加了登录页面，当用户登录时，用户导航到项目页面，然后asynctask无法获得结果。在调试asynctask工作，但在运行应用程序时，asynctask通常不起作用。如果我在微调器上选择类别，asynctask工作。我想，它是关于在微调器选择的项目上调用asynctask但我不知道如何修复它。

再次，在调试程序按预期工作，但是当我正常运行应用程序asynctask无法获取项目。我必须在微调器中选择类别才能按预期工作。

登录页面：

public class LoginUser extends AsyncTask<String,String,String>{

        private ProgressDialog dialog = new ProgressDialog(LoginActivity.this);
        private String UName;
        private String PWord;

        public LoginUser(String user_name,String pass_word){
            this.UName = user_name;
            this.PWord = pass_word;
        }

        @Override
         protected void onPreExecute() {
            dialog.setMessage("Please wait...");
            dialog.show();
         }

        @Override
        protected String doInBackground(String... params) {
            String uid = GetUser(UName,PWord);
            return uid;
        }

        protected void onPostExecute(String uid){

            if(uid.equals("0")){
                Toast toast = Toast.makeText(getBaseContext(), "Login failed.", Toast.LENGTH_SHORT);
                toast.show();
            }
            else{
                SPE = SP.edit();
                SPE.putString("username", username);
                SPE.putString("password", password);
                SPE.putString("user_id", user_id);
                SPE.commit();
                Intent intent = new Intent(LoginActivity.this,MainActivity.class);
                bundle.putString("login", "login");
                intent.putExtras(bundle);
                startActivity(intent);
            }
            dialog.dismiss();
        }

    }

项目页面：

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        intent = new Intent(MainActivity.this,ItemActivity.class);
        bundle = new Bundle();

        veriler = getIntent().getExtras();       
        String PageLogin = "";
        PageLogin = veriler.getString("login");

        spn = (Spinner)findViewById(R.id.spinner1);
        items = new String[4][0];
        categories = new String[11];
        categories[0] = "All";
        categories[1] = "Computers";
        categories[2] = "Mobile";
        categories[3] = "Home Electronics";
        categories[4] = "Fashion";
        categories[5] = "Magazines";
        categories[6] = "Health & Beauty";
        categories[7] = "Movie & Music";
        categories[8] = "Furnitures";
        categories[9] = "Toys";
        categories[10] = "Accessories";

        ArrayAdapter<String> spn_adapter = new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_spinner_item, categories);
        spn_adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spn.setAdapter(spn_adapter); 

        if(PageLogin.equals("login")){
            CatID="0";
            new GetAllItemsAS().execute();
        }

        spn.setOnItemSelectedListener(new OnItemSelectedListener(){

            public void onItemSelected(AdapterView<?> arg0, View arg1,
                    int arg2, long arg3) {

                selectedCat = spn.getSelectedItem().toString().trim();  
                if(selectedCat.equals("All")){
                    CatID="0";
                }
                else if(selectedCat.equals("Computers")){
                    CatID="1";
                }
                else if(selectedCat.equals("Mobile")){
                    CatID="2";
                }
                else if(selectedCat.equals("Home Electronics")){
                    CatID="3";
                }
                else if(selectedCat.equals("Fashion")){
                    CatID="4";
                }
                else if(selectedCat.equals("Magazines")){
                    CatID="5";
                }
                else if(selectedCat.equals("Health & Beauty")){
                    CatID="6";
                }
                else if(selectedCat.equals("Movie & Music")){
                    CatID="7";
                }
                else if(selectedCat.equals("Furnitures")){
                    CatID="8";
                }
                else if(selectedCat.equals("Toys")){
                    CatID="9";
                }
                else if(selectedCat.equals("Accessories")){
                    CatID="10";
                }
                new GetAllItemsAS().execute();
            }
            public void onNothingSelected(AdapterView<?> arg0) {
                CatID="0";
                new GetAllItemsAS().execute();
            }                   
        }); 
    }

所有代码：

LoginActivity：

public class LoginActivity extends Activity {

    SharedPreferences SP;
    SharedPreferences.Editor SPE;
    private String username;
    private String password;
    private String user_id;

    private Bundle bundle;

    private String _username;
    private String _password;

    private TextView _usernameTxt;
    private TextView _passwordTxt;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        bundle = new Bundle();

        SP = getSharedPreferences("UserInfoXML", MODE_PRIVATE);

        _usernameTxt = (TextView)findViewById(R.id.userNameSignInTxt);
        _passwordTxt = (TextView)findViewById(R.id.PasswordSignInTxt);
        Button login = (Button)findViewById(R.id.SignInButton);

        login.setOnClickListener(new OnClickListener(){

            public void onClick(View v) {
                username = _usernameTxt.getText().toString();
                password = _passwordTxt.getText().toString();
                new LoginUser(username,password).execute();
            }
        });

    }

    public class LoginUser extends AsyncTask<String,String,String>{

        private ProgressDialog dialog = new ProgressDialog(LoginActivity.this);
        private String UName;
        private String PWord;

        public LoginUser(String user_name,String pass_word){
            this.UName = user_name;
            this.PWord = pass_word;
        }

        @Override
         protected void onPreExecute() {
            dialog.setMessage("Please wait...");
            dialog.show();
         }

        @Override
        protected String doInBackground(String... params) {
            String uid = GetUser(UName,PWord);
            return uid;
        }

        protected void onPostExecute(String uid){

            if(uid.equals("0")){
                Toast toast = Toast.makeText(getBaseContext(), "Login failed.", Toast.LENGTH_SHORT);
                toast.show();
            }
            else{
                SPE = SP.edit();
                SPE.putString("username", username);
                SPE.putString("password", password);
                SPE.putString("user_id", user_id);
                SPE.commit();
                Intent intent = new Intent(LoginActivity.this,MainActivity.class);
                bundle.putString("login", "login");
                intent.putExtras(bundle);
                startActivity(intent);
            }
            dialog.dismiss();
        }

    }


    public String GetUser(String user_name,String pass_word){
        String id = null;

        PropertyInfo kulad = new PropertyInfo();
        kulad.name= "username";
        kulad.setValue(user_name);
        kulad.type = PropertyInfo.STRING_CLASS;

        PropertyInfo parola = new PropertyInfo();
        parola.name= "password";
        parola.setValue(pass_word);
        parola.type = PropertyInfo.STRING_CLASS;

        SoapObject request = new SoapObject("http://shopar.org/", "Login");
        request.addProperty(kulad);
        request.addProperty(parola);


        SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);
        envelope.bodyOut=request;
        envelope.dotNet = true; 
        envelope.setOutputSoapObject(request);

        HttpTransportSE androidHttpTransport = new HttpTransportSE("http://service.melihmucuk.com/ShopArWS.asmx");
        androidHttpTransport.debug = true;

       try {

       androidHttpTransport.call("http://shopar.org/Login", envelope);
       SoapPrimitive response = (SoapPrimitive) envelope.getResponse();
       id = String.valueOf(response.toString());
} 
        catch (Exception e) {           
            e.printStackTrace();
            id = "0";
       }
        return id;
    }

MainActivity：

public class MainActivity extends Activity {

    private String[] categories;
    private String[][] items;
    private String selectedCat = "All";
    private String CatID = "0";
    private Spinner spn;
    private Intent intent;
    private Bundle bundle;
    private Bundle veriler;

private String[][] GetAllItems(){

        SoapObject request = new SoapObject("http://shopar.org/", "GetAllItem");
        SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);
        envelope.dotNet = true;     
        envelope.setOutputSoapObject(request);
        //http://192.168.2.240/ShopArService/ShopArWS.asmx
        HttpTransportSE androidHttpTransport = new HttpTransportSE("http://service.melihmucuk.com/ShopArWS.asmx");
        androidHttpTransport.debug = true;

       try {

       androidHttpTransport.call("http://shopar.org/GetAllItem", envelope);
       SoapObject response = (SoapObject) envelope.getResponse();
       int allCounter=0;
       int catCounter=0;
       String cat_id="";

       for(int i=0;i<response.getPropertyCount();i++){    
           Object property = response.getProperty(i);
           if(property instanceof SoapObject){
               SoapObject item = (SoapObject) property;
               cat_id = item.getProperty("cat_id").toString();
               if(CatID.equals("0")){
                   allCounter++;
               }
               else if(CatID.equals(cat_id)){
                   catCounter++;
               }
           }
       }

       if(CatID.equals("0")){
           items[0] = new String[response.getPropertyCount()]; //item_id
           items[1] = new String[response.getPropertyCount()]; //price
           items[2] = new String[response.getPropertyCount()]; //title
           items[3] = new String[response.getPropertyCount()]; //desc


           for(int i=0;i<response.getPropertyCount();i++){    
               Object property = response.getProperty(i);
               if(property instanceof SoapObject){
                   SoapObject item = (SoapObject) property;
                   String item_id = item.getProperty("item_id").toString();
                   String price = item.getProperty("price").toString() + " TL";
                   String title = item.getProperty("title").toString();
                   String desc = item.getProperty("desc").toString();
                       items[0][i] = item_id;
                       items[1][i] = price;
                       items[2][i] = title;
                       items[3][i] = desc;
               }    
       }

       }
       else{
           items[0] = new String[catCounter]; //item_id
           items[1] = new String[catCounter]; //price
           items[2] = new String[catCounter]; //title
           items[3] = new String[catCounter]; //desc

           for(int k=0;k<catCounter;k++){
               for(int i=0;i<response.getPropertyCount();i++){    
                   Object property = response.getProperty(i);
                   if(property instanceof SoapObject){
                       SoapObject item = (SoapObject) property;
                       String item_id = item.getProperty("item_id").toString();
                       String price = item.getProperty("price").toString() + " TL";
                       String title = item.getProperty("title").toString();
                       String desc = item.getProperty("desc").toString();
                       String catid = item.getProperty("cat_id").toString();
                       List <String> list = Arrays.asList(items[0]);
                       if(CatID.equals(catid)){
                           if(list.contains(item_id)){

                           }
                           else{
                               items[0][k] = item_id;
                               items[1][k] = price;
                               items[2][k] = title;
                               items[3][k] = desc;
                               break;
                           }
                       }
                   } 
               } 
           }   
       }
    }
        catch (Exception e) {           
            e.printStackTrace();
       }   
       return items;
    }

public class GetAllItemsAS extends AsyncTask<String,String,String[][]>{

    private ProgressDialog dialog = new ProgressDialog(MainActivity.this);
    @Override
     protected void onPreExecute() {
        dialog.setMessage("Loading...");
        dialog.show();
     }

    @Override
    protected String[][] doInBackground(String... params) {
        GetAllItems();
        return items;
    }

    protected void onPostExecute(String[][] items){
        ASFinish();
        dialog.dismiss();
    }

}

public void ASFinish(){
    ListView liste = (ListView)findViewById(R.id.listView1);
    ListArrayAdapter adapter = new ListArrayAdapter(MainActivity.this,items[2],items[3],items[1],items[0]);
    liste.setAdapter(adapter);
    liste.setOnItemClickListener(new AdapterView.OnItemClickListener(){

        public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                long arg3) {                
            bundle.putString("item_id", items[0][arg2]);
            intent.putExtras(bundle);
            startActivity(intent);              
        }           
    });
}

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

//      intent = new Intent(MainActivity.this,ItemActivity.class);
//        bundle = new Bundle();

        veriler = getIntent().getExtras();       
        String PageLogin = "";
        if(veriler != null){
            PageLogin = veriler.getString("login");
        }

        spn = (Spinner)findViewById(R.id.spinner1);
        items = new String[4][0];
        categories = new String[11];
        categories[0] = "All";
        categories[1] = "Computers";
        categories[2] = "Mobile";
        categories[3] = "Home Electronics";
        categories[4] = "Fashion";
        categories[5] = "Magazines";
        categories[6] = "Health & Beauty";
        categories[7] = "Movie & Music";
        categories[8] = "Furnitures";
        categories[9] = "Toys";
        categories[10] = "Accessories";

        ArrayAdapter<String> spn_adapter = new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_spinner_item, categories);
        spn_adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        spn.setAdapter(spn_adapter); 

        if(PageLogin.equals("login")){
            CatID="0";
            new GetAllItemsAS().execute();
        }

        spn.setOnItemSelectedListener(new OnItemSelectedListener(){

            public void onItemSelected(AdapterView<?> arg0, View arg1,
                    int arg2, long arg3) {

                selectedCat = spn.getSelectedItem().toString().trim();  
                if(selectedCat.equals("All")){
                    CatID="0";
                }
                else if(selectedCat.equals("Computers")){
                    CatID="1";
                }
                else if(selectedCat.equals("Mobile")){
                    CatID="2";
                }
                else if(selectedCat.equals("Home Electronics")){
                    CatID="3";
                }
                else if(selectedCat.equals("Fashion")){
                    CatID="4";
                }
                else if(selectedCat.equals("Magazines")){
                    CatID="5";
                }
                else if(selectedCat.equals("Health & Beauty")){
                    CatID="6";
                }
                else if(selectedCat.equals("Movie & Music")){
                    CatID="7";
                }
                else if(selectedCat.equals("Furnitures")){
                    CatID="8";
                }
                else if(selectedCat.equals("Toys")){
                    CatID="9";
                }
                else if(selectedCat.equals("Accessories")){
                    CatID="10";
                }
                new GetAllItemsAS().execute();
            }
            public void onNothingSelected(AdapterView<?> arg0) {
                CatID="0";
                new GetAllItemsAS().execute();
            }                   
        }); 
    }

Answer 1

在onCreate方法上，你不应该创建一个新的意图，只需获得启动活动的意图。删除这一行：

intent = new Intent(MainActivity.this,ItemActivity.class);
bundle = new Bundle();

然后像你一样得到变量：

veriler = getIntent().getExtras();       
String PageLogin = "";
if(veriler != null)
   PageLogin = veriler.getString("login");

另请尊重java coding conventions。