myAdapter无法解析

Question

我正在尝试在Android中创建一个ViewPager，但Android Studio告诉我'myAdapter无法解析'。这是我的代码：

public class MainActivity extends FragmentActivity {

GridView gridview_id;
FloatingActionButton fab_main;
ViewPager pager;
objectAdapter oa;
MainActivity activity;
Fragment fragment;




@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater =  getMenuInflater();
    inflater.inflate(R.menu.menu, menu);
    final MenuItem searchItem = menu.findItem(R.id.action_search);
    SearchView searchView = (SearchView)
            MenuItemCompat.getActionView(searchItem);
    searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
        @Override
        public boolean onQueryTextSubmit(String query) {
            oa.filter(query);


            return false;
        }

        @Override
        public boolean onQueryTextChange(String newText) {


            return false;
        }


    });
    return true;
}

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

    fab_main = (FloatingActionButton) findViewById(R.id.fab_main);
    gridview_id = (GridView) findViewById(R.id.gridview_id);
    pager = (ViewPager) findViewById(R.id.pager);
    fab_main.show();

    AdView mAdView = (AdView) findViewById(R.id.adView);
    //AdRequest adRequest = new AdRequest.Builder()
            //.addTestDevice("YOUR_DEVICE_HASH")
            //.build();

    //do not make visible while testing!!
    mAdView.loadAd(adRequest);


    android.support.v4.app.FragmentManager fragmentManager = getSupportFragmentManager();


    gridview_id.setAdapter(new objectAdapter(this));
    pager.setAdapter(new myAdapter(fragmentManager));

    class myAdapter extends FragmentPagerAdapter {


        public myAdapter(android.support.v4.app.FragmentManager fm) {
            super(fm);

        }

        @Override
        public android.support.v4.app.Fragment getItem(int position) {
            if (position == 0) {
                activity = new MainActivity();

            }
            if (position == 1) {
                fragment = new DailyIntakeActivity();
                fab_main.hide();
            }
            return null;
        }

        @Override
        public int getCount() {
            return 2;
        }
    }

            setDefaultKeyMode(DEFAULT_KEYS_SEARCH_LOCAL);
            fab_main.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    fab_main.hide();
                    onSearchRequested();

                }


            });

            gridview_id.setOnItemClickListener(new AdapterView.OnItemClickListener() {

                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    fab_main.hide();
                    Intent intent = new Intent(view.getContext(), SecondActivity.class);
                    objectAdapter.ViewHolder holder = (objectAdapter.ViewHolder) view.getTag();
                    SingleItem temp = (SingleItem) holder.myItem.getTag();
                    intent.putExtra("image", temp.image);
                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                        ActivityOptionsCompat options = ActivityOptions.makeSceneTransitionAnimation(MainActivity.this, temp.image, getString(R.string.image_transition));
                        startActivity(intent, options.toBundle());
                    } else {
                        startActivity(intent);
                    }

                }
            });

        }
    }