AndroidStudioのテンプレートにあるNavigationDrawerActivityのNavigationDrawerに[こちら](https://github.com/idunnololz/AnimatedExpandableListView)のサイトを参考にして改良して見たのですが､以下のエラーがでてしまいました｡

**エラー:**

```

    02-01 18:14:39.571  23825-23825/com.hoge.zousan.poyo E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: com.hoge.zousan.piyo, PID: 23825
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.hoge.zousan.piyo/com.hoge.zousan.piyo.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.hoge.zousan.piyo.NavigationDrawerFragment.setUp(int, android.support.v4.widget.DrawerLayout)' on a null object reference
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
            at android.app.ActivityThread.access$800(ActivityThread.java:144)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.hoge.zousan.piyo.NavigationDrawerFragment.setUp(int, android.support.v4.widget.DrawerLayout)' on a null object reference
            at com.hoge.zousan.piyo.MainActivity.onCreate(MainActivity.java:42)
            at android.app.Activity.performCreate(Activity.java:5933)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)
    
```

以下に`MainActivity`と`NavigationDrawerFragment`と各`Layout.xml`を示します｡

**MainActivity.java:**

```

    public class MainActivity extends ActionBarActivity
        implements NavigationDrawerFragment.NavigationDrawerCallbacks, PopularVideoFragment.OnFragmentInteractionListener, VideoSearchFragment.OnFragmentInteractionListener,
    SkillPracticeFragment.OnFragmentInteractionListener{
    
    /**
     * Fragment managing the behaviors, interactions and presentation of the navigation drawer.
     */
    private NavigationDrawerFragment mNavigationDrawerFragment;
    
    /**
     * Used to store the last screen title. For use in {@link #restoreActionBar()}.
     */
    private CharSequence mTitle;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    
        mNavigationDrawerFragment = (NavigationDrawerFragment)
                getSupportFragmentManager().findFragmentById(R.id.navigation_drawer);
        mTitle = getTitle();
    
    
        // Set up the drawer.
        mNavigationDrawerFragment.setUp(
                R.id.navigation_drawer,
                (DrawerLayout) findViewById(R.id.drawer_layout));
    
        //初期画面を表示
        /*
        android.app.FragmentManager fragmentManager = getFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.FragmentContainer, VideoSearchFragment.newInstance());
        fragmentTransaction.commit();
        */
    
    
    
        FragmentManager fm = getSupportFragmentManager();
        android.support.v4.app.FragmentTransaction fragmentTransaction = fm.beginTransaction();
        fragmentTransaction.replace(R.id.FragmentContainer, PopularVideoFragment.newInstance());
        fragmentTransaction.commit();
    }
    
    
    @Override
    public void onNavigationDrawerItemSelected(int position) {
        // update the main content by replacing fragments
        FragmentManager fragmentManager = getSupportFragmentManager();
        android.support.v4.app.FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        switch (position){
            case 0:
                fragmentTransaction.replace(R.id.FragmentContainer, PopularVideoFragment.newInstance());
                break;
            case 1:
                fragmentTransaction.replace(R.id.FragmentContainer, SkillPracticeFragment.newInstance());
                break;
            case 2:
                //fragmentTransaction.replace(R.id.FragmentContainer, ChannelFragment.newInstance());
                break;
            case 3:
                //fragmentTransaction.replace(R.id.FragmentContainer, PlaylistFragment.newInstance());
                break;
        }
        fragmentTransaction.commit();
    }
    
    public void onSectionAttached(int number) {
        switch (number) {
            case 1:
                mTitle = getString(R.string.title_popular);
                break;
            case 2:
                mTitle = getString(R.string.title_skill);
    
                break;
            case 3:
                mTitle = getString(R.string.title_channel);
    
                break;
            case 4:
                mTitle = getString(R.string.title_playlist);
    
                break;
        }
    }
    
    public void restoreActionBar() {
        ActionBar actionBar = getSupportActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
        actionBar.setDisplayShowTitleEnabled(true);
        actionBar.setTitle(mTitle);
    }
    
    
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        if (!mNavigationDrawerFragment.isDrawerOpen()) {
            // Only show items in the action bar relevant to this screen
            // if the drawer is not showing. Otherwise, let the drawer
            // decide what to show in the action bar.
            getMenuInflater().inflate(R.menu.main, menu);
            restoreActionBar();
            return true;
        }
        return super.onCreateOptionsMenu(menu);
    }
    
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
    
        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }
    
        return super.onOptionsItemSelected(item);
    }
    
    @Override
    public void onFragmentInteraction(Uri uri) {
    
    }
    
    @Override
    public void onFragmentInteraction(String id){
    
    }
    
    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        private static final String ARG_SECTION_NUMBER = "section_number";
    
        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static PlaceholderFragment newInstance(int sectionNumber) {
            PlaceholderFragment fragment = new PlaceholderFragment();
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);
            return fragment;
        }
    
        public PlaceholderFragment() {
        }
    
        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main, container, false);
            return rootView;
        }
    
        @Override
        public void onAttach(Activity activity) {
            super.onAttach(activity);
            ((MainActivity) activity).onSectionAttached(
                    getArguments().getInt(ARG_SECTION_NUMBER));
        }
    }
    
    }
    
```

**NavigationDrawerFragment.java**

```

    public class NavigationDrawerFragment extends Fragment {
    
    /**
     * Remember the position of the selected item.
     */
    private static final String STATE_SELECTED_POSITION = "selected_navigation_drawer_position";
    
    /**
     * Per the design guidelines, you should show the drawer on launch until the user manually
     * expands it. This shared preference tracks this.
     */
    private static final String PREF_USER_LEARNED_DRAWER = "navigation_drawer_learned";
    
    /**
     * A pointer to the current callbacks instance (the Activity).
     */
    private NavigationDrawerCallbacks mCallbacks;
    
    /**
     * Helper component that ties the action bar to the navigation drawer.
     */
    private android.support.v7.app.ActionBarDrawerToggle mDrawerToggle;
    
    private DrawerLayout mDrawerLayout;
    private ListView mDrawerListView;
    //追加したやつ
    private AnimatedExpandableListView mExListView;
    private ExAdapter adapter;
    private View mFragmentContainerView;
    
    private int mCurrentSelectedPosition = 0;
    private boolean mFromSavedInstanceState;
    private boolean mUserLearnedDrawer;
    
    private DrawerArrowDrawable drawerArrowDrawable;
    
    public NavigationDrawerFragment() {
    }
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    
        // Read in the flag indicating whether or not the user has demonstrated awareness of the
        // drawer. See PREF_USER_LEARNED_DRAWER for details.
        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(getActivity());
        mUserLearnedDrawer = sp.getBoolean(PREF_USER_LEARNED_DRAWER, false);
    
        drawerArrowDrawable = new DrawerArrowDrawable(getResources());
        drawerArrowDrawable.setStrokeColor(Color.WHITE);
    
        if (savedInstanceState != null) {
            mCurrentSelectedPosition = savedInstanceState.getInt(STATE_SELECTED_POSITION);
            mFromSavedInstanceState = true;
    
            drawerArrowDrawable.restoreState(savedInstanceState);
        }
    
        // Select either the default item (0) or the last selected item.
        selectItem(mCurrentSelectedPosition);
    }
    
    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        // Indicate that this fragment would like to influence the set of actions in the action bar.
        setHasOptionsMenu(true);
    }
    
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        mDrawerListView = (ListView) inflater.inflate(
                R.layout.fragment_navigation_drawer, container, false);
        /*
        mDrawerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                selectItem(position);
            }
        });
        mDrawerListView.setAdapter(new ArrayAdapter<String>(
                getActionBar().getThemedContext(),
                android.R.layout.simple_list_item_activated_1,
                android.R.id.text1,
                new String[]{
                        getString(R.string.title_popular),
                        getString(R.string.title_skill),
                        getString(R.string.title_channel),
                        getString(R.string.title_playlist)
                }));
        mDrawerListView.setItemChecked(mCurrentSelectedPosition, true);
        return mDrawerListView;
        */
        /*ここからオリジナル*/
        List<GroupItem> items = new ArrayList<GroupItem>();
    
        String[] groupNameList = {getString(R.string.title_popular), getString(R.string.title_skill),
                getString(R.string.title_channel), getString(R.string.title_playlist)};
        String[] childNameList = {getString(R.string.title_today), getString(R.string.title_last_week),
                getString(R.string.title_last_month), getString(R.string.title_latest), getString(R.string.title_skill_all)};
        String[] childHintList = {getString(R.string.hint_today), getString(R.string.hint_last_week),
                getString(R.string.hint_last_month), getString(R.string.hint_latest), getString(R.string.hint_all)};
    
    
        for(int i=0; i<4; i++){
            GroupItem item = new GroupItem();
    
            item.title = groupNameList[i];
    
            switch (i){
                case 0:
                    for(int j=0; j<3; j++) {
                        ChildItem child = new ChildItem();
                        child.title = childNameList[j];
                        child.hint = childHintList[j];
                        item.items.add(child);
                    }
                    break;
                case 1:
                    for(int j=3; j<5; j++){
                        ChildItem child = new ChildItem();
                        child.title = childNameList[j];
                        child.hint = childHintList[j];
                        item.items.add(child);
                    }
                    break;
            }
            items.add(item);
        }
    
        adapter = new ExAdapter(getActivity());
        adapter.setData(items);
    
        mExListView = (AnimatedExpandableListView)mDrawerListView.findViewById(R.id.ex_list_view);
    
        mExListView.setAdapter(adapter);
    
        mExListView.setOnGroupClickListener(new ExpandableListView.OnGroupClickListener() {
            @Override
            public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
                if (mExListView.isGroupExpanded(groupPosition)) {
                    mExListView.collapseGroupWithAnimation(groupPosition);
                } else {
                    mExListView.expandGroupWithAnimation(groupPosition);
                }
                return true;
            }
        });
    
        mExListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
            @Override
            public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
                switch (groupPosition){
                    case 0:
                        switch (childPosition){
                            case 0:
                                FragmentManager fm = getFragmentManager();
                                FragmentTransaction transaction = fm.beginTransaction();
                                transaction.replace(R.id.FragmentContainer, VideoSearchFragment.newInstance(0, 0));
                        }
                }
                return true;
            }
        });
    
        /*ここまでオリジナル*/
    
        return mDrawerListView;
    }
    
    public boolean isDrawerOpen() {
        return mDrawerLayout != null && mDrawerLayout.isDrawerOpen(mFragmentContainerView);
    }
    
    /**
     * Users of this fragment must call this method to set up the navigation drawer interactions.
     *
     * @param fragmentId   The android:id of this fragment in its activity's layout.
     * @param drawerLayout The DrawerLayout containing this fragment's UI.
     */
    public void setUp(int fragmentId, DrawerLayout drawerLayout) {
        mFragmentContainerView = getActivity().findViewById(fragmentId);
        mDrawerLayout = drawerLayout;
    
        // 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
    
        ActionBar actionBar = getActionBar();
        actionBar.setDisplayHomeAsUpEnabled(true);
        actionBar.setHomeButtonEnabled(true);
    
        // ActionBarDrawerToggle ties together the the proper interactions
        // between the navigation drawer and the action bar app icon.
        mDrawerToggle = new MaterialActionDrawerToggle(drawerArrowDrawable,
                getActivity(),                    /* host Activity */
                mDrawerLayout,                    /* DrawerLayout object */            /* nav drawer image to replace 'Up' caret */
                R.string.navigation_drawer_open,  /* "open drawer" description for accessibility */
                R.string.navigation_drawer_close  /* "close drawer" description for accessibility */
        ) {
            @Override
            public void onDrawerClosed(View drawerView) {
                super.onDrawerClosed(drawerView);
                if (!isAdded()) {
                    return;
                }
    
                getActivity().supportInvalidateOptionsMenu(); // calls onPrepareOptionsMenu()
            }
    
            @Override
            public void onDrawerOpened(View drawerView) {
                super.onDrawerOpened(drawerView);
                if (!isAdded()) {
                    return;
                }
    
                if (!mUserLearnedDrawer) {
                    // The user manually opened the drawer; store this flag to prevent auto-showing
                    // the navigation drawer automatically in the future.
                    mUserLearnedDrawer = true;
                    SharedPreferences sp = PreferenceManager
                            .getDefaultSharedPreferences(getActivity());
                    sp.edit().putBoolean(PREF_USER_LEARNED_DRAWER, true).apply();
                }
    
                getActivity().supportInvalidateOptionsMenu(); // calls onPrepareOptionsMenu()
            }
        };
    
        // If the user hasn't 'learned' about the drawer, open it to introduce them to the drawer,
        // per the navigation drawer design guidelines.
        if (!mUserLearnedDrawer && !mFromSavedInstanceState) {
            mDrawerLayout.openDrawer(mFragmentContainerView);
        }
    
        // Defer code dependent on restoration of previous instance state.
        mDrawerLayout.post(new Runnable() {
            @Override
            public void run() {
                mDrawerToggle.syncState();
            }
        });
    
        mDrawerLayout.setDrawerListener(mDrawerToggle);
    }
    
    private void selectItem(int position) {
        mCurrentSelectedPosition = position;
        if (mDrawerListView != null) {
            mDrawerListView.setItemChecked(position, true);
        }
        if (mDrawerLayout != null) {
            mDrawerLayout.closeDrawer(mFragmentContainerView);
        }
        if (mCallbacks != null) {
            mCallbacks.onNavigationDrawerItemSelected(position);
        }
    }
    
    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mCallbacks = (NavigationDrawerCallbacks) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException("Activity must implement NavigationDrawerCallbacks.");
        }
    }
    
    @Override
    public void onDetach() {
        super.onDetach();
        mCallbacks = null;
    }
    
    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt(STATE_SELECTED_POSITION, mCurrentSelectedPosition);
        drawerArrowDrawable.onSaveInstanceState(outState);
    }
    
    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        // Forward the new configuration the drawer toggle component.
        mDrawerToggle.onConfigurationChanged(newConfig);
    }
    
    @Override
    public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
        // If the drawer is open, show the global app actions in the action bar. See also
        // showGlobalContextActionBar, which controls the top-left area of the action bar.
        if (mDrawerLayout != null && isDrawerOpen()) {
            inflater.inflate(R.menu.global, menu);
            showGlobalContextActionBar();
        }
        super.onCreateOptionsMenu(menu, inflater);
    }
    
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (mDrawerToggle.onOptionsItemSelected(item)) {
            return true;
        }
    
        if (item.getItemId() == R.id.action_example) {
            Toast.makeText(getActivity(), "Example action.", Toast.LENGTH_SHORT).show();
            return true;
        }
    
        return super.onOptionsItemSelected(item);
    }
    
    /**
     * Per the navigation drawer design guidelines, updates the action bar to show the global app
     * 'context', rather than just what's in the current screen.
     */
    private void showGlobalContextActionBar() {
        ActionBar actionBar = getActionBar();
        actionBar.setDisplayShowTitleEnabled(true);
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
        actionBar.setTitle(R.string.app_name);
    }
    
    private ActionBar getActionBar() {
        return ((ActionBarActivity) getActivity()).getSupportActionBar();
    }
    
    /**
     * Callbacks interface that all activities using this fragment must implement.
     */
    public static interface NavigationDrawerCallbacks {
        /**
         * Called when an item in the navigation drawer is selected.
         */
        void onNavigationDrawerItemSelected(int position);
    }
    
    /*追加内部クラス*/
    private static class GroupItem{
        String title;
        List<ChildItem> items = new ArrayList<ChildItem>();
    }
    private static class ChildItem{
        String title;
        String hint;
    }
    private static class ChildHolder{
        TextView title;
        TextView hint;
    }
    private static class GroupHolder{
        TextView title;
    }
    
    private class ExAdapter extends AnimatedExpandableListView.AnimatedExpandableListAdapter{
        private LayoutInflater inflater;
    
        private List<GroupItem> items;
    
        public ExAdapter(Context context){
            inflater = LayoutInflater.from(context);
        }
    
        public void setData(List<GroupItem> items){
            this.items=items;
        }
    
        @Override
        public ChildItem getChild(int groupPosition, int childPosition){
            return items.get(groupPosition).items.get(childPosition);
        }
    
        @Override
        public long getChildId(int groupPosition, int childPosition){
            return childPosition;
        }
    
        @Override
        public View getRealChildView(int groupPosition, int childPosition, boolean isLastChild,
                                     View convertView, ViewGroup parent){
            ChildHolder holder;
            ChildItem item = getChild(groupPosition, childPosition);
            if(convertView == null){
                holder = new ChildHolder();
                convertView = inflater.inflate(R.layout.drawer_item, parent, false);
                holder.title = (TextView)convertView.findViewById(R.id.text_title);
                holder.hint = (TextView)convertView.findViewById(R.id.text_hint);
                convertView.setTag(holder);
            }else{
                holder = (ChildHolder)convertView.getTag();
            }
    
            holder.title.setText(item.title);
            holder.hint.setText(item.hint);
    
            return convertView;
        }
    
        @Override
        public int getRealChildrenCount(int groupPosition){
            return items.get(groupPosition).items.size();
        }
    
        @Override
        public GroupItem getGroup(int groupPosition){
            return items.get(groupPosition);
        }
    
        @Override
        public int getGroupCount(){
            return items.size();
        }
    
        @Override
        public long getGroupId(int groupPosition){
            return groupPosition;
        }
    
        @Override
        public View getGroupView(int groupPosition, boolean isExpanded, View convertView, ViewGroup parent){
            GroupHolder holder;
            GroupItem item = getGroup(groupPosition);
            if(convertView == null){
                holder = new GroupHolder();
                convertView = inflater.inflate(R.layout.drawer_item_group, parent, false);
                holder.title = (TextView)convertView.findViewById(R.id.text_title);
                convertView.setTag(holder);
            }else{
                holder = (GroupHolder)convertView.getTag();
            }
            holder.title.setText(item.title);
    
            return convertView;
        }
    
        @Override
        public boolean hasStableIds(){
            return true;
        }
    
        @Override
        public boolean isChildSelectable(int arg0, int arg1){
            return true;
        }
    }
    }
    
```

**fragment_navigation_drawer.xml**

```

    <AnimateListView.AnimatedExpandableListView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:choiceMode="singleChoice"
    android:divider="@android:color/transparent" android:dividerHeight="0dp"
    android:background="#cccc" tools:context=".NavigationDrawerFragment"
    android:id="@+id/ex_list_view"/>
    
```

**activity_main.xml:**

```

    <!-- A DrawerLayout is intended to be used as the top-level content view using match_parent for both width and height to consume the full space available. -->
    <android.support.v4.widget.DrawerLayout     xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:id="@+id/drawer_layout"
    android:layout_width="match_parent" android:layout_height="match_parent"
    tools:context=".MainActivity">
    
    <!-- As the main content view, the view below consumes the entire
         space available using match_parent in both dimensions. -->
    
    <FrameLayout
        android:id="@+id/FragmentContainer"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"></FrameLayout>
    
    <!-- android:layout_gravity="start" tells DrawerLayout to treat
         this as a sliding drawer on the left side for left-to-right
         languages and on the right side for right-to-left languages.
         If you're not building against API 17 or higher, use
         android:layout_gravity="left" instead. -->
    <!-- The drawer is given a fixed width in dp and extends the full height of
         the container. -->
    <FrameLayout android:id="@+id/navigation_drawer"
        android:layout_width="@dimen/navigation_drawer_width" android:layout_height="match_parent"
        android:layout_gravity="start"
        android:name="com.hoge.zousan.piyo.NavigationDrawerFragment"
        tools:layout="@layout/fragment_navigation_drawer">
    </FrameLayout>
    
```

おそらく､AndroidStudioのテンプレートのどこかに原因があるのたと考えたのですが､それがどこなのか私の力不足ゆえ発見できませんでした｡  
`NavigationDrawer`を表示させて､アイテムを選択するところまでに必要なことを教えて下さい｡ よろしくお願いします｡
CC BY-SA 3.0
2015-02-01T09:55:53.260
5693
2015-02-01T09:55:53.260
7232
question
android android-studio
AndroidStudioのテンプレートを改造したい｡(NavigationDrawerActivity)