显示工具栏菜单，但在实现片段时不​​可单击

Question

每当我在onCreate方法中使用SectionsStateManager来获取要显示的片段时，工具栏仍然是可见的（连同其菜单项一样），但完全不可单击。下面是我的MainActivity的onCreate方法，片段的（MainFeed）onCreateView方法和SectionsStatePagerAdapter的代码。

更新：还包括 activity_main

MainActivity的onCreate

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

        Toolbar toolbar = findViewById(R.id.tool_bar);
        setSupportActionBar(toolbar);
        Log.d(TAG, "onCreate: Started.");

        RedditClient redditClient = new RedditClient(UserAgent.of("android",
                "com.digitalnode.feedr", "v0.0.1", "TheFiveHundred"));
        TokenStore store = new RedditTokenStore(
                PreferenceManager.getDefaultSharedPreferences(MainActivity.this));
        RefreshTokenHandler refreshTokenHandler = new RefreshTokenHandler(store, redditClient);

        AuthenticationManager manager = AuthenticationManager.get();
        manager.init(redditClient, refreshTokenHandler);

        main_auth_manager = manager;

        mSectionsStatePagerAdapter = new SectionsStatePagerAdapter(getSupportFragmentManager());

        mViewPager = (ViewPager) findViewById(R.id.container);
        //setup the pager
        setupViewPager(mViewPager);
    }

我的片段的onCreateView方法

public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable final Bundle savedInstanceState) {
        View view  = inflater.inflate(R.layout.main_feed_layout, container, false);
        Log.d(TAG, "onCreateView: started.");

        mRecyclerView = (RecyclerView) view.findViewById(R.id.my_recycler_view);

        // use this setting to improve performance if you know that changes
        // in content do not change the layout size of the RecyclerView
        mRecyclerView.setHasFixedSize(true);

        // use a linear layout manager
        mLayoutManager = new LinearLayoutManager(getContext());
        mRecyclerView.setLayoutManager(mLayoutManager);

        redditClient = new RedditClient(UserAgent.of("android",
                "com.digitalnode.feedr", "v0.0.1", "TheFiveHundred"));
        TokenStore store = new RedditTokenStore(
                PreferenceManager.getDefaultSharedPreferences(getContext()));
        RefreshTokenHandler refreshTokenHandler = new RefreshTokenHandler(store, redditClient);

        AuthenticationManager manager = AuthenticationManager.get();
        manager.init(redditClient, refreshTokenHandler);

        Entry[] arr = new Entry[entryList.size()];

        for(int i = 0; i < arr.length; i++)
        {
            arr[i] = entryList.get(i);
        }
        // specify an adapter (see also next example)
        Log.d("posts", "" + entryList);
        mAdapter = new EntryAdapter(arr);
        mRecyclerView.setAdapter(mAdapter);

        //if(redditIsLoggedIn())
            //new SetUpReddit().execute();

        return view;
    }

SectionsStatePagerAdapter

public class SectionsStatePagerAdapter extends FragmentStatePagerAdapter {

    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public SectionsStatePagerAdapter(FragmentManager fm) {
        super(fm);
    }

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

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

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

activity_main布局

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <include
        layout = "@layout/toolbar"
        android:id="@+id/tool_bar"/>

    <android.support.v4.view.ViewPager
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/container">

    </android.support.v4.view.ViewPager>

</android.support.constraint.ConstraintLayout>