Вызов метода интерфейса в фрагменте бросает ClassCastException

Question

Это проблематично линия в моем коде:

listAdapter.setCustomButtonListener((CustomButtonListener) getActivity());** 

Этот слушатель прекрасно работает внутри AppCompatActivity, но когда я пытаюсь использовать его внутри фрагмента он бросает ClassCastException. Это LogCat:

Logcat

FATAL EXCEPTION: main Process: info.tranetech.laundry, PID: 21707 
                     java.lang.ClassCastException: info.tranetech.laundry.pricelist.ItemListTab cannot be cast to tranetech.laundry.pricelist.CustomButtonListener 
                      at info.tranetech.laundry.pricelist.ManItems$GetContacts.onPostExecute(ManItems.java:177) 
                      at info.tranetech.laundry.pricelist.ManItems$GetContacts.onPostExecute(ManItems.java:98) 
                      at android.os.AsyncTask.finish(AsyncTask.java:632) 
                      at android.os.AsyncTask.access$600(AsyncTask.java:177) 
                      at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645) 
                      at android.os.Handler.dispatchMessage(Handler.java:102) 
                      at android.os.Looper.loop(Looper.java:146) 
                      at android.app.ActivityThread.main(ActivityThread.java:5748) 
                      at java.lang.reflect.Method.invokeNative(Native Method) 
                      at java.lang.reflect.Method.invoke(Method.java:515) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107) 
                      at dalvik.system.NativeStart.main(Native Method) 

Это мой интерфейс

CustomButtonListener.java

public interface CustomButtonListener { 
    public void onButtonClickListener(int position, EditText editText, int value); 
} 

Это моя TabBar (AppCompatActivity)

ItemListTab.java

public class ItemListTab extends AppCompatActivity { 

    private Toolbar toolbar; 
    private TabLayout tabLayout; 
    private ViewPager viewPager; 
    private int[] tabIcons = { 
      R.drawable.ic_tab_favourite, 
      R.drawable.ic_tab_call, 
      R.drawable.ic_tab_contacts 
    }; 

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

     toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 
     getSupportActionBar().setDisplayHomeAsUpEnabled(true); 

     viewPager = (ViewPager) findViewById(R.id.viewpager); 
     setupViewPager(viewPager); 

     tabLayout = (TabLayout) findViewById(R.id.tabs); 
     tabLayout.setupWithViewPager(viewPager); 
     setupTabIcons(); 
    } 

    private void setupTabIcons() { 
     tabLayout.getTabAt(0).setIcon(tabIcons[0]); 
     tabLayout.getTabAt(1).setIcon(tabIcons[1]); 
     tabLayout.getTabAt(2).setIcon(tabIcons[2]); 
     tabLayout.getTabAt(3).setIcon(tabIcons[0]); 
    } 

    private void setupViewPager(ViewPager viewPager) { 
     ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager()); 
     adapter.addFrag(new ManItems(), ""); 
     adapter.addFrag(new WomanItems(), ""); 
     adapter.addFrag(new KidItems(), ""); 
     adapter.addFrag(new HouseHoldItems(), ""); 
     viewPager.setAdapter(adapter); 
    } 

    class ViewPagerAdapter extends FragmentPagerAdapter { 
     private final List<Fragment> mFragmentList = new ArrayList<>(); 
     private final List<String> mFragmentTitleList = new ArrayList<>(); 

     public ViewPagerAdapter(FragmentManager manager) { 
      super(manager); 
     } 

     @Override 
     public Fragment getItem(int position) { 
      return mFragmentList.get(position); 
     } 

     @Override 
     public int getCount() { 
      return mFragmentList.size(); 
     } 

     public void addFrag(Fragment fragment, String title) { 
      mFragmentList.add(fragment); 
      mFragmentTitleList.add(title); 
     } 

     @Override 
     public CharSequence getPageTitle(int position) { 
      return mFragmentTitleList.get(position); 
     } 
    } 
} 

Это мой фрагмент, где я называю

listAdapter.setCustomButtonListener ((CustomButtonListener) getActivity());

ManItems.java

public class ManItems extends Fragment implements CustomButtonListener{ 

    private ListView listView; 
    View rootView; 
    Context context; 
    private ListAdapter listAdapter; 
    public static String[] ItemName, prices,ItemImage; 
    Button PlaceOrder; 
    ProgressDialog pDialog; 
    HashMap<String, String> itemMap; 
    // Hashmap for ListView 
    ArrayList<HashMap<String, String>> ItemList = new ArrayList<HashMap<String, String>>(); 


    public ManItems() { 
     // Required empty public constructor 
    } 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     // Inflate the layout for this fragment 
     rootView = inflater.inflate(R.layout.content_main, container, false); 

     listView = (ListView) rootView.findViewById(R.id.customListView); 
     PlaceOrder = (Button) rootView.findViewById(R.id.place_order); 

     // Calling async task to get json 
     new GetContacts().execute(); 


     PlaceOrder.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 

       if (ListAdapter.map.isEmpty()) { 
        Toast.makeText(getActivity(), "Please select items", Toast.LENGTH_SHORT).show(); 
       } else { 
        ListAdapter.map.values().removeAll(Collections.singleton("0")); 
        Intent intent = new Intent(getActivity(), OrderList.class); 
        startActivity(intent); 
       } 
      } 
     }); 

     return rootView; 
    } 

    @Override 
    public void onButtonClickListener(int position, EditText editText, int value) { 
     // View view = listView.getChildAt(position); 
     int quantity = Integer.parseInt(editText.getText().toString()); 

     quantity = quantity + 1 * value; 
     if (quantity < 0) 
      quantity = 0; 
     editText.setText(quantity + ""); 

    } 

    /** 
    * Async task class to get json by making HTTP call 
    */ 
    private class GetContacts extends AsyncTask<Void, Void, Void> { 

     @Override 
     protected void onPreExecute() { 
      super.onPreExecute(); 
      // Showing progress dialog 
      pDialog = new ProgressDialog(getActivity()); 
      pDialog.setMessage("Please wait..."); 
      pDialog.setCancelable(false); 
      pDialog.show(); 

     } 

     @Override 
     protected Void doInBackground(Void... arg0) { 
      // Creating service handler class instance 
      JSONParser JP = new JSONParser(); 

      // Making a request to url and getting response 
      String jsonStr = JP.makeServiceCall("http://openspace.tranetech.com/mis/Laundry/items.php", JSONParser.GET); 

      Log.d("Response: ", "> " + jsonStr); 

      if (jsonStr != null) { 
       try { 
        JSONObject jsonObj = new JSONObject(jsonStr); 

        // Getting JSON Array node 
        JSONArray itmeArray = jsonObj.getJSONArray("Data"); 

        ItemName = new String[itmeArray.length()]; 
        prices = new String[itmeArray.length()]; 
        ItemImage = new String[itmeArray.length()]; 

        // looping through All Contacts 
        for (int i = 0; i < itmeArray.length(); i++) { 
         JSONObject item = itmeArray.getJSONObject(i); 

         String price = item.getString("price").toString(); 
         String name = item.getString("item_name").toString(); 
         String image = item.getString("image").toString(); 

         ItemName[i] = name; 
         prices[i] = price; 
         ItemImage[i] =image; 

        } 
       } catch (JSONException e) { 
        e.printStackTrace(); 
       } 
      } else { 
       Log.e("ServiceHandler", "Couldn't get any data from the url"); 
      } 

      return null; 
     } 

     @Override 
     protected void onPostExecute(Void result) { 
      super.onPostExecute(result); 
      // Dismiss the progress dialog 
      if (pDialog.isShowing()) { 

       for (int z = 0; z < ItemName.length; z++) { 

        Log.d("Name ", "" + ItemName[z]); 
        Log.d("Price ", "" + prices[z]); 
        Log.d("Images ", "" + ItemImage[z]); 
       } 
       pDialog.dismiss(); 

      } 
//   images = getResources().obtainTypedArray(R.array.ProductImages); 

      /** 
      * Updating parsed JSON data into ListView 
      * */ 
      listAdapter = new ListAdapter(getActivity(), ItemName, ItemImage, prices); 
      listView.setAdapter(listAdapter); 
      listAdapter.setCustomButtonListener((CustomButtonListener) getActivity()); 

     } 
    } 


} 

После изменения этого listAdapter.setCustomButtonListener (ManItems.this);

Logcat

 java.lang.NullPointerException 
                      at info.tranetech.laundry.pricelist.ListAdapter.getView(ListAdapter.java:95) 
                      at android.widget.AbsListView.obtainView(AbsListView.java:2768) 
                      at android.widget.ListView.makeAndAddView(ListView.java:1817) 
                      at android.widget.ListView.fillDown(ListView.java:703) 
                      at android.widget.ListView.fillFromTop(ListView.java:769) 
                      at android.widget.ListView.layoutChildren(ListView.java:1647) 
                      at android.widget.AbsListView.onLayout(AbsListView.java:2586) 
                      at android.view.View.layout(View.java:15903) 
                      at android.view.ViewGroup.layout(ViewGroup.java:4932) 
                      at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1692) 
                      at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1534) 
                      at android.widget.LinearLayout.onLayout(LinearLayout.java:1443) 
                      at android.view.View.layout(View.java:15903) 
                      at android.view.ViewGroup.layout(ViewGroup.java:4932) 
                      at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1627) 
                      at android.view.View.layout(View.java:15903) 
                      at android.view.ViewGroup.layout(ViewGroup.java:4932) 
                      at android.support.design.widget.CoordinatorLayout.layoutChild(CoordinatorLayout.java:1034) 
                      at android.support.design.widget.CoordinatorLayout.onLayoutChild(CoordinatorLayout.java:744) 
                      at android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:42) 
                      at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1180) 
                      at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:757) 
                      at android.view.View.layout(View.java:15903) 
                      at android.view.ViewGroup.layout(ViewGroup.java:4932) 
                      at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453) 
                      at android.widget.FrameLayout.onLayout(FrameLayout.java:388) 
                      at android.view.View.layout(View.java:15903) 
                      at android.view.ViewGroup.layout(ViewGroup.java:4932) 
                      at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1692) 
                      at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1534) 
                      at android.widget.LinearLayout.onLayout(LinearLayout.java:1443) 
                      at android.view.View.layout(View.java:15903) 
                      at android.view.ViewGroup.layout(ViewGroup.java:4932) 
                      at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453) 
                      at android.widget.FrameLayout.onLayout(FrameLayout.java:388) 
                      at android.view.View.layout(View.java:15903) 
                      at android.view.ViewGroup.layout(ViewGroup.java:4932) 
                      at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1692) 
                      at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1534) 
                      at android.widget.LinearLayout.onLayout(LinearLayout.java:1443) 
                      at android.view.View.layout(View.java:15903) 
                      at android.view.ViewGroup.layout(ViewGroup.java:4932) 
                      at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453) 
                      at android.widget.FrameLayout.onLayout(FrameLayout.java:388) 
                      at android.view.View.layout(View.java:15903) 
                      at android.view.ViewGroup.layout(ViewGroup.java:4932) 
                      at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2418) 
                      at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2133) 
                      at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1297) 
                      at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6773) 
                      at android.view.Choreographer$CallbackRecord.run(Choreographer.java:813) 
                      at android.view.Choreographer.doCallbacks(Choreographer.java:613) 
                      at android.view.Choreographer.doFrame(Choreographer.java:583) 
                      at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:799) 
                      at android.os.Handler.handleCallback(Handler.java:733) 
                      at android.os.Handler.dispatchMessage(Handler.java:95) 
                      at android.os.Looper.loop(Looper.java:146) 
                      at android.app.ActivityThread.main(ActivityThread.java:5748) 
                      at java.lang.reflect.Method.invokeNative(Native Method) 
                      at java.lang.reflect.Method.invoke(Method.java:515) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1291) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1107) 

    [1]: https://www.vlemonn.com/Blog/Android/Android-Custom-ListView-with-ImageView-EditText-and-Button/ 

Ошибка Расположение

for (int z = 0; z < MainActivity_items.ItemImage.length; z++) { 

      Picasso.with(context) 
        .load(""+MainActivity_items.ItemImage[position]) 
        .into(listViewHolder.ivProduct); 
     } 

ListAdapter.java

public class ListAdapter extends BaseAdapter { 

    public ArrayList<Integer> quantity = new ArrayList<Integer>(); 
    public ArrayList<Integer> price = new ArrayList<Integer>(); 
    private String[] listViewItems, prices, static_price; 
    String[] images; 
    View row = null; 

    static String get_price, get_quntity; 
    int g_quntity, g_price, g_minus; 

    private Context context; 
    CustomButtonListener customButtonListener; 

    static HashMap<String, Integer> map = new HashMap<>(); 


    public ListAdapter(Context context, String[] listViewItems, String[] images, String[] prices) { 
     this.context = context; 
     this.listViewItems = listViewItems; 
     this.images = images; 
     this.prices = prices; 

     for (int i = 0; i < listViewItems.length; i++) { 
      quantity.add(0); 
     } 
    } 

    public void setCustomButtonListener(CustomButtonListener customButtonListner) { 
     this.customButtonListener = customButtonListner; 
    } 

    @Override 
    public int getCount() { 
     return listViewItems.length; 
    } 

    @Override 
    public String getItem(int position) { 
     return listViewItems[position]; 
    } 


    @Override 
    public long getItemId(int position) { 
     return 0; 
    } 

    @Override 
    public View getView(final int position, View convertView, ViewGroup parent) { 

     final ListViewHolder listViewHolder; 
     if (convertView == null) { 
      LayoutInflater layoutInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
      row = layoutInflater.inflate(R.layout.activity_custom_listview, parent, false); 
      listViewHolder = new ListViewHolder(); 
      listViewHolder.tvProductName = (TextView) row.findViewById(R.id.tvProductName); 
      listViewHolder.ivProduct = (ImageView) row.findViewById(R.id.ivproduct); 
      listViewHolder.tvPrices = (TextView) row.findViewById(R.id.tvProductPrice); 
      listViewHolder.btnPlus = (ImageButton) row.findViewById(R.id.ib_addnew); 
      listViewHolder.edTextQuantity = (EditText) row.findViewById(R.id.editTextQuantity); 
      listViewHolder.btnMinus = (ImageButton) row.findViewById(R.id.ib_remove); 
      static_price = context.getResources().getStringArray(R.array.Price); 
      row.setTag(listViewHolder); 
     } else { 
      row = convertView; 
      listViewHolder = (ListViewHolder) convertView.getTag(); 
     } 

     //Loading image from below url into imageView 

for (int z = 0; z < MainActivity_items.ItemImage.length; z++) { 
    Picasso.with(context) 
      .load(""+MainActivity_items.ItemImage[position]) 
      .into(listViewHolder.ivProduct); 
} 

//  listViewHolder.ivProduct.setImageResource(images.getResourceId(position, -1)); 
     listViewHolder.edTextQuantity.setText(quantity.get(position) + ""); 
     listViewHolder.tvProductName.setText(listViewItems[position]); 
     listViewHolder.tvPrices.setText(prices[position]); 


     listViewHolder.btnPlus.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       if (customButtonListener != null) { 
        customButtonListener.onButtonClickListener(position, listViewHolder.edTextQuantity, 1); 

        quantity.set(position, quantity.get(position) + 1); 
        //price.set(position, price.get(position) + 1); 

        row.getTag(position); 

        get_price = listViewHolder.tvPrices.getText().toString(); 

        g_price = Integer.valueOf(static_price[position]); 

        get_quntity = listViewHolder.edTextQuantity.getText().toString(); 
        g_quntity = Integer.valueOf(get_quntity); 

        Integer.parseInt(listViewHolder.edTextQuantity.getText().toString()); 
        map.put("" + listViewHolder.tvProductName.getText().toString(), Integer.valueOf(Integer.parseInt(listViewHolder.edTextQuantity.getText().toString()))); 
//     Log.d("A ", "" + a); 
//     Toast.makeText(context, "A" + a, Toast.LENGTH_LONG).show(); 
//     Log.d("Position ", "" + position); 
//     System.out.println(+position + " Values " + map.values()); 
        listViewHolder.tvPrices.getTag(); 
        listViewHolder.tvPrices.setText("" + g_price * g_quntity); 
        ShowHashMapValue(); 

       } 


      } 

     }); 
     listViewHolder.btnMinus.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       if (customButtonListener != null) { 

        customButtonListener.onButtonClickListener(position, listViewHolder.edTextQuantity, -1); 
        if (quantity.get(position) > 0) 
         quantity.set(position, quantity.get(position) - 1); 

        get_price = listViewHolder.tvPrices.getText().toString(); 
        g_minus = Integer.valueOf(get_price); 
        g_price = Integer.valueOf(static_price[position]); 
        int minus = g_minus - g_price; 
        if (minus >= g_price) { 
         listViewHolder.tvPrices.setText("" + minus); 
        } 
        map.put("" + listViewHolder.tvProductName.getText().toString(), Integer.valueOf(Integer.parseInt(listViewHolder.edTextQuantity.getText().toString()))); 
        ShowHashMapValue(); 
       } 
      } 
     }); 


     return row; 
    } 

    private void ShowHashMapValue() { 
     /** 
     * get the Set Of keys from HashMap 
     */ 
     Set setOfKeys = map.keySet(); 

/** 
* get the Iterator instance from Set 
*/ 
     Iterator iterator = setOfKeys.iterator(); 

/** 
* Loop the iterator until we reach the last element of the HashMap 
*/ 
     while (iterator.hasNext()) { 
/** 
* next() method returns the next key from Iterator instance. 
* return type of next() method is Object so we need to do DownCasting to String 
*/ 
      String key = (String) iterator.next(); 

/** 
* once we know the 'key', we can get the value from the HashMap 
* by calling get() method 
*/ 
      int value = map.get(key); 

      System.out.println("Key: " + key + ", Value: " + value); 
     } 
    } 
} 

Answer 1

Как сказано в сообщении об ошибке, активность ItemListTab не может быть отнесена к CustomButtonListener, поскольку она не реализует ее, - текущий фрагмент. Таким образом, вы должны изменить

listAdapter.setCustomButtonListener((CustomButtonListener) getActivity()); 

в

listAdapter.setCustomButtonListener(ManItems.this); 
/* Not listAdapter.setCustomButtonListener(this), otherwise 
you would be referring to the AsyncTask 'GetContacts' itself */