convertView.getTag(); create Cast Error

Question

Я использую фрагмент для создания ListView, заполненный CheckBox es. Я попытался изо всех сил найти решение, основанное на других вопросах, но я не могу его исправить. Когда я запускаю сценарий без использования:

convertView.getTag(); 

Мое приложение работает нормально, но позиции Пункт с в списке не спасают так. Элементы просмотра перемещаются. Однако, когда я использую этот метод, я получаю сообщение об ошибке. Состояние логарифма:

01-02 23:54:20.662: E/InputEventReceiver(1209): Exception dispatching input event. 
01-02 23:54:20.672: D/AndroidRuntime(1209): Shutting down VM 
01-02 23:54:20.672: W/dalvikvm(1209): threadid=1: thread exiting with uncaught exception (group=0x40a13300) 
01-02 23:54:20.782: E/AndroidRuntime(1209): FATAL EXCEPTION: main 
01-02 23:54:20.782: E/AndroidRuntime(1209): java.lang.ClassCastException: com.MrBabilin.youdeserveadrink.Items cannot be cast to com.MrBabilin.youdeserveadrink.AlcoholList$MyCustomAdapter$ViewHolder 
01-02 23:54:20.782: E/AndroidRuntime(1209):  at com.MrBabilin.youdeserveadrink.AlcoholList$MyCustomAdapter.getView(AlcoholList.java:169) 
01-02 23:54:20.782: E/AndroidRuntime(1209):  at android.widget.AbsListView.obtainView(AbsListView.java:2255) 
01-02 23:54:20.782: E/AndroidRuntime(1209):  at android.widget.ListView.makeAndAddView(ListView.java:1769) 
01-02 23:54:20.782: E/AndroidRuntime(1209):  at android.widget.ListView.fillDown(ListView.java:672) 
01-02 23:54:20.782: E/AndroidRuntime(1209):  at android.widget.ListView.fillGap(ListView.java:636) 
01-02 23:54:20.782: E/AndroidRuntime(1209):  at android.widget.AbsListView.trackMotionScroll(AbsListView.java:5040) 
01-02 23:54:20.782: E/AndroidRuntime(1209):  at 

Эта деятельность состоит из 3-х классов. Основной один: IngredientsActivity

public class IngredientsActivity extends FragmentActivity implements ActionBar.TabListener { 

    private static final String STATE_SELECTED_NAVIGATION_ITEM = "selected_navigation_item"; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 

     super.onCreate(savedInstanceState); 
     setContentView(R.layout.check_list); 
     getActionBar().setTitle("Search"); 
     getActionBar().setIcon(R.drawable.search_1); 

     // Set up the action bar. 
     final ActionBar actionBar = getActionBar(); 
     actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); 

     // For each of the sections in the app, add a tab to the action bar. 
     actionBar.addTab(actionBar.newTab().setText("Alcahol").setTabListener(this)); 
     actionBar.addTab(actionBar.newTab().setText("Juice").setTabListener(this)); 
     actionBar.addTab(actionBar.newTab().setText("Other").setTabListener(this)); 
    } 

    @Override 
    public void onRestoreInstanceState(Bundle savedInstanceState) { 

     if (savedInstanceState.containsKey(STATE_SELECTED_NAVIGATION_ITEM)) { 
      getActionBar().setSelectedNavigationItem(savedInstanceState.getInt(STATE_SELECTED_NAVIGATION_ITEM)); 
     } 
    } 

    @Override 
    public void onSaveInstanceState(Bundle outState) { 
     super.onSaveInstanceState(outState); 

     outState.putInt(STATE_SELECTED_NAVIGATION_ITEM, getActionBar().getSelectedNavigationIndex()); 
    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 

     return true; 
    } 



    @Override 
    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) { 
    } 

    @Override 
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) { 


     if (tab.getPosition() == 0) { 
      AlcoholList simpleListFragment = new AlcoholList(); 
      getSupportFragmentManager().beginTransaction().replace(R.id.containert, simpleListFragment).commit(); 
     } 
     else if (tab.getPosition() == 1) { 
      JuiceList androidlidt = new JuiceList(); 
      getSupportFragmentManager().beginTransaction().replace(R.id.containert, androidlidt).commit(); 
     } 



     else { 

      OtherList androidversionlist = new OtherList(); 
      getSupportFragmentManager().beginTransaction().replace(R.id.containert, androidversionlist).commit(); 

     } 
    } 

    @Override 
    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) { 
    } 

     public static class DummySectionFragment extends Fragment { 
     public DummySectionFragment() { 
     } 

     public static final String ARG_SECTION_NUMBER = "section_number"; 

     @Override 
     public View onCreateView(LayoutInflater inflater, ViewGroup container, 
       Bundle savedInstanceState) { 
      TextView textView = new TextView(getActivity()); 
      textView.setGravity(Gravity.CENTER); 
      Bundle args = getArguments(); 
      textView.setText(Integer.toString(args.getInt(ARG_SECTION_NUMBER))); 
      return textView; 
     } 
    } 



} 

затем фрагмент: AlcoholList

import android.content.Context; 
import android.content.SharedPreferences; 
import android.os.Bundle; 
import android.preference.PreferenceManager; 
import android.support.v4.app.ListFragment; 
import android.util.Log; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.ArrayAdapter; 
import android.widget.CheckBox; 
import android.widget.ListView; 

public class AlcoholList extends ListFragment{ 
    MyCustomAdapter dataAdapter = null; 
    private Set<String> recipesList = new HashSet<String>(); 
private ArrayList<Items> stateList = new ArrayList<Items>(); 


public AlcoholList() { 
      Items _states1 = new Items ("Gin",false); 
      stateList.add(_states1); 
Items _states2 = new Items ("Ginger Liqueur",false); 
      stateList.add(_states2); 
Items _states3 = new Items ("Citrus Vodka",false); 
      stateList.add(_states3); 
Items _states4 = new Items ("Champagne",false); 
      stateList.add(_states4); 
Items _states5 = new Items ("Coconut Rum",false); 
      stateList.add(_states5); 
Items _states6 = new Items ("Pear Vodka",false); 
      stateList.add(_states6); 
Items _states7 = new Items ("Rum",false); 
      stateList.add(_states7); 
Items _states8 = new Items ("Tequila",false); 
      stateList.add(_states8); 
Items _states9 = new Items ("Triple Sec",false); 
      stateList.add(_states9); 
Items _states10 = new Items ("Kahlua",false); 
      stateList.add(_states10); 
Items _states11 = new Items ("Vanilla Vodka",false); 
      stateList.add(_states11); 
Items _states12 = new Items ("Sake",false); 
      stateList.add(_states12); 
Items _states13 = new Items ("Bourbon",false); 
      stateList.add(_states13); 
Items _states14 = new Items ("Vodka",false); 
      stateList.add(_states14); 
Items _states15 = new Items ("Beer",false); 
      stateList.add(_states15); 


     }; 


    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
      dataAdapter = new MyCustomAdapter(this.getActivity(),R.layout.da_item, stateList); 
      setListAdapter(dataAdapter); 
      SharedPreferences sharedPreferences = PreferenceManager 
        .getDefaultSharedPreferences(getActivity()); 
     recipesList = sharedPreferences.getStringSet("string", recipesList); 
    } 


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

     return inflater.inflate(R.layout.list_fragment, container, false); 
    } 


    @Override 
    public void onListItemClick(ListView list, View v, int position, long id) { 


    } 

    private class MyCustomAdapter extends ArrayAdapter<Items> 
    { 

    private ArrayList<Items> stateList; 
    public MyCustomAdapter(Context context, int textViewResourceId, 

      ArrayList<Items> stateList) 
      { 
        super(context, textViewResourceId, stateList); 
        this.stateList = new ArrayList<Items>(); 
        this.stateList.addAll(stateList); 
      } 


    private class ViewHolder 
     { 

     CheckBox name; 
     } 
    @Override 
    public View getView (int position, View convertView, ViewGroup parent) 
     { 

       ViewHolder holder = null; 

       Log.v("ConvertView", String.valueOf(position)); 

       if (convertView == null) 
       { 

        LayoutInflater vi = (LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE); 

       convertView = vi.inflate(R.layout.da_item, null); 

       holder = new ViewHolder(); 
       convertView.setTag(holder); 

       holder.name = (CheckBox) convertView.findViewById(R.id.ingredientbox); 



          holder.name.setOnClickListener(new View.OnClickListener() 
          { 
            public void onClick(View v) 
            { 
             CheckBox cb = (CheckBox) v; 
             Items _state = (Items) cb.getTag(); 
             _state.setSelected(cb.isChecked()); 
            } 
          }); 

       } 
       else 
       { 

        holder = (ViewHolder) convertView.getTag(); // THIS IS THE PROBLEM 

       } 

       Items state = stateList.get(position); 


       holder.name.setText(state.getName()); 
       holder.name.setChecked(state.isSelected()); 

       holder.name.setTag(state); 

       return convertView; 
     } 

    } 
} 

то класс массива: Элементы

public class Items { 
String name ; 
boolean selected; 


public Items(String name, boolean selected){ 
    super(); 
    this.name=name; 
    this.selected=selected; 
} 


public String getName() { 
    return name; 
} 


public void setName(String name) { 
    this.name = name; 
} 


public boolean isSelected() { 
    return selected; 
} 


public void setSelected(boolean selected) { 
    this.selected = selected; 
} 
} 

Я не знаю, если это полезно, но эта проблема не произошло, прежде чем я попытался реализовать представления фрагментов. Код, который работал был:

public class IngredientsActivity extends Activity { 
    MyCustomAdapter dataAdapter = null; 

      @Override 
      public void onCreate(Bundle savedInstanceState) 
      { 
      super.onCreate(savedInstanceState); 
      setContentView(R.layout.check_list); 
      //Generate list View from ArrayList 
       displayListView(); 
      } 
        private void displayListView() 
      { 

        //Array list of countries 
        ArrayList<Items> stateList = new ArrayList<Items>(); 
         Items _states2 = new Items ("420" ,false); 

         stateList.add(_states2); 

        Items _states3 = new Items ("Amanda Bynes" ,false); 

         stateList.add(_states3); 

        Items _states4 = new Items ("Angelina Jolie" ,false); 

         stateList.add(_states4); 

        Items _states5 = new Items ("Anne Hathaway" ,false); 

         stateList.add(_states5); 

        Items _states6 = new Items ("Bachelorette Contestants" ,false); 

         stateList.add(_states6); 

        Items _states7 = new Items ("Beauty and the Beast" ,false); 

         stateList.add(_states7); 

        Items _states8 = new Items ("Beyonce" ,false); 

         stateList.add(_states8); 

        Items _states9 = new Items ("Big Boi" ,false); 

         stateList.add(_states9); 

        Items _states10 = new Items ("Charlie Sheen" ,false); 

         stateList.add(_states10); 

        } 
        //create an ArrayAdaptar from the String Array 
        dataAdapter = new MyCustomAdapter(this,R.layout.da_item, stateList); 
        ListView listViews = (ListView) findViewById(R.id.ingList2); 
        // Assign adapter to ListView 
        listViews.setAdapter(dataAdapter);  
      } 
private class MyCustomAdapter extends ArrayAdapter<Items> 
{ 
private ArrayList<Items> stateList; 
public MyCustomAdapter(Context context, int textViewResourceId, 
ArrayList<Items> stateList) 
{ 
     super(context, textViewResourceId, stateList); 
     this.stateList = new ArrayList<Items>(); 
     this.stateList.addAll(stateList); 
} 
    private class ViewHolder 
    { 
    CheckBox name; 
    } 




    @Override 
public View getView(int position, View convertView, ViewGroup parent) 
    { 
      ViewHolder holder = null; 
      Log.v("ConvertView", String.valueOf(position)); 
      if (convertView == null) 
      { 
      LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
      convertView = vi.inflate(R.layout.da_item, null); 
      holder = new ViewHolder(); 
      holder.name = (CheckBox) convertView.findViewById(R.id.ingredientbox); 
      convertView.setTag(holder); 
         holder.name.setOnClickListener(new View.OnClickListener() 
         { 
           public void onClick(View v) 
           { 
            CheckBox cb = (CheckBox) v; 
            Items _state = (Items) cb.getTag(); 
            _state.setSelected(cb.isChecked()); 
           } 
         }); 
      } 
      else 
      { 
       holder = (ViewHolder) convertView.getTag(); 
      } 
      Items state = stateList.get(position); 
      holder.name.setText(state.getName()); 
      holder.name.setChecked(state.isSelected()); 
      holder.name.setTag(state); 
      return convertView; 
    } 

} 
} 

Вопрос: Как я могу предотвратить мое заявление от сбоя, при вызове convertView.getTag()

Answer 1

R.layout.da_item файл содержит только R.id.ingredientbox так что ваши covertView и holder.name относятся к одному и тому же объекту.

Теперь, когда вы звоните

convertView.setTag(holder); 

держатель установлен в теге объекта convertView, а затем вы называете

holder.name.setTag(state); 

который переопределяет тег, как оба объекта являются одинаковыми.

Попробуйте удалить второй звонок и проверьте его.

EDIT Изменить класс держатель для:

private class ViewHolder 
     { 
     Items state; 
     CheckBox name; 
     } 

не пишут holder.name.setTag(state);. Вместо этого сделать следующее:

holder.state=state; 

Теперь, когда вы хотите детали просто сказать:

Items _state = ((ViewHolder) cb.getTag()).state;