setAdapter, приводящий к сбою приложения

Question

Когда я вызываю метод setAdapter в нижней части кода внутри класса фрагмента, это вызвало мое приложение сбой перед запуском. Однако, когда я прокомментирую это, приложение работает просто отлично (очевидно, без адаптера).

package com.example.android.navigationdrawerexample; 

import android.app.Activity; 
import android.app.Fragment; 
import android.app.FragmentManager; 
import android.content.res.Configuration; 
import android.os.Bundle; 
import android.support.v4.app.ActionBarDrawerToggle; 
import android.support.v4.view.GravityCompat; 
import android.support.v4.widget.DrawerLayout; 
import android.view.LayoutInflater; 
import android.view.Menu; 
import android.view.MenuInflater; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.AdapterView; 
import android.widget.ArrayAdapter; 
import android.widget.AutoCompleteTextView; 
import android.widget.ListView; 

public class MainActivity extends Activity { 
private DrawerLayout mDrawerLayout; 
private ListView mDrawerList; 
private ActionBarDrawerToggle mDrawerToggle; 

private CharSequence mDrawerTitle; 
private CharSequence mTitle; 
private String[] mNavigationTitles; 


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

    mTitle = mDrawerTitle = getTitle(); 
    mNavigationTitles = getResources().getStringArray(R.array.navigaton_array); 
    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout); 
    mDrawerList = (ListView) findViewById(R.id.left_drawer); 

    // set a custom shadow that overlays the main content when the drawer opens 
    mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START); 
    // set up the drawer's list view with items and click listener 
    mDrawerList.setAdapter(new ArrayAdapter<String>(this, 
      R.layout.drawer_list_item, mNavigationTitles)); 
    mDrawerList.setOnItemClickListener(new DrawerItemClickListener()); 

    // enable ActionBar app icon to behave as action to toggle nav drawer 
    getActionBar().setDisplayHomeAsUpEnabled(true); 
    getActionBar().setHomeButtonEnabled(true); 

    // ActionBarDrawerToggle ties together the the proper interactions 
    // between the sliding drawer and the action bar app icon 
    mDrawerToggle = new ActionBarDrawerToggle(
      this,     /* host Activity */ 
      mDrawerLayout,   /* DrawerLayout object */ 
      R.drawable.ic_drawer, /* nav drawer image to replace 'Up' caret */ 
      R.string.drawer_open, /* "open drawer" description for accessibility */ 
      R.string.drawer_close /* "close drawer" description for accessibility */ 
      ) { 
     public void onDrawerClosed(View view) { 
      getActionBar().setTitle(mTitle); 
      invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu() 
     } 

     public void onDrawerOpened(View drawerView) { 
      getActionBar().setTitle(mDrawerTitle); 
      invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu() 
     } 
    }; 
    mDrawerLayout.setDrawerListener(mDrawerToggle); 

    if (savedInstanceState == null) { 
     selectItem(0); 
    } 
} 

@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    MenuInflater inflater = getMenuInflater(); 
    inflater.inflate(R.menu.main, menu); 
    return super.onCreateOptionsMenu(menu); 
} 

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    // The action bar home/up action should open or close the drawer. 
    // ActionBarDrawerToggle will take care of this. 
    if (mDrawerToggle.onOptionsItemSelected(item)) { 
     return true; 
    } 
    // Handle action buttons 
    switch(item.getItemId()) { 

    default: 
     return super.onOptionsItemSelected(item); 
    } 
} 

/* The click listner for ListView in the navigation drawer */ 
private class DrawerItemClickListener implements ListView.OnItemClickListener { 
    @Override 
    public void onItemClick(AdapterView<?> parent, View view, int position, long id) { 
     selectItem(position); 
    } 
} 

private void selectItem(int position) { 
    // update the main content by replacing fragments 
    Fragment fragment = new NavigationFragment(); 
    Bundle args = new Bundle(); 
    args.putInt(NavigationFragment.ARG_NAVIGATION_POSITION, position); 
    fragment.setArguments(args); 

    FragmentManager fragmentManager = getFragmentManager(); 
    fragmentManager.beginTransaction().replace(R.id.content_frame, fragment).commit(); 

    // update selected item and title, then close the drawer 
    mDrawerList.setItemChecked(position, true); 
    setTitle(mNavigationTitles[position]); 
    mDrawerLayout.closeDrawer(mDrawerList); 
} 

@Override 
public void setTitle(CharSequence title) { 
    mTitle = title; 
    getActionBar().setTitle(mTitle); 
} 
/** 
* When using the ActionBarDrawerToggle, you must call it during 
* onPostCreate() and onConfigurationChanged()... 
*/ 

@Override 
protected void onPostCreate(Bundle savedInstanceState) { 
    super.onPostCreate(savedInstanceState); 
    // Sync the toggle state after onRestoreInstanceState has occurred. 
    mDrawerToggle.syncState(); 
} 

@Override 
public void onConfigurationChanged(Configuration newConfig) { 
    super.onConfigurationChanged(newConfig); 
    // Pass any configuration change to the drawer toggls 
    mDrawerToggle.onConfigurationChanged(newConfig); 
} 
/** 
* Fragment that appears in the "content_frame", shows a planet 
*/ 
public static class NavigationFragment extends Fragment { 
    public static final String ARG_NAVIGATION_POSITION = "navgation_position"; 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
      Bundle savedInstanceState) { 
     View rootView = inflater.inflate(R.layout.fragment_navigation, container, false); 
     int i = getArguments().getInt(ARG_NAVIGATION_POSITION); 
     String navigation = getResources().getStringArray(R.array.navigaton_array)[i]; 

     AutoCompleteTextView countriesAutoComplete = (AutoCompleteTextView) getActivity().findViewById(R.id.countries_autoComplete); 
     String[] countriesListFullName = getResources().getStringArray(R.array.countryNames); 
     ArrayAdapter<String> adapter = new ArrayAdapter<String>(countriesAutoComplete.getContext(), android.R.layout.simple_dropdown_item_1line, countriesListFullName); 
     countriesAutoComplete.setAdapter(adapter); 
     countriesAutoComplete.setThreshold(1); 
     //int imageId = getResources().getIdentifier()(navigation.toLowerCase(Locale.getDefault()), 
     //    "drawable", getActivity().getPackageName()); 
     // ((ImageView) rootView.findViewById(R.id.image)).setImageResource(imageId); 
     getActivity().setTitle(navigation); 
     return rootView; 
    } 
} 

}

Answer 1

Изменить

AutoCompleteTextView countriesAutoComplete = (AutoCompleteTextView) getActivity().findViewById(R.id.countries_autoComplete); 

в

AutoCompleteTextView countriesAutoComplete = (AutoCompleteTextView) rootView.findViewById(R.id.countries_autoComplete); // use rootView.findViewById 

findViewById выглядит для представления в текущем надутом макете. Поэтому вам нужно использовать объект inlfated view для инициализации вашего AutoCompleteTextView