http://li2.me/2016/08/make-a-reusable-ui-in-android-app-development.html

TwoFragmentsActivity.java

/**
 * Created by weiyi.li on 4/7/16.
 * This activity includes {@link AlbumFragment} and {@link ThumbnailFragment}.
 */
public class TwoFragmentsActivity extends BasicOperationActivity {
    private boolean mShowingThumbnail = true;
    @Dvr.DvrFolder private int mFolderType = Dvr.DVR_FOLDER_LOOPED_VIDEOS;
    private FragmentManager mFm;
    private AlbumFragment mAlbumFragment;
    private ThumbnailFragment mThumbnailFragment;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mActionTitleView.setOnClickListener(mOnActionTitleClickedListener);
        mFm = getSupportFragmentManager();
        showThumbnailFragment(mFolderType);
    }

    @NonNull
    @Override
    protected Fragment createContentFragment() {
        return null;
    }

    @Override
    protected void onOperationButton1Clicked() {
    }

    @Override
    protected void onOperationButton2Clicked() {
    }


    /** Implements listeners to response to UI touch events. */

    private DebouncedOnClickListener mOnActionTitleClickedListener = new DebouncedOnClickListener() {
        @Override
        public void onDebouncedClick(View v) {
            if (mShowingThumbnail) {
                showAlbumFragment();
                hideThumbnailFragment();

            } else {
                hideAlbumFragment();
                showThumbnailFragment(mFolderType);
            }
        }
    };

    private AlbumFragment.OnAlbumClickListener mOnAlbumClickListener = new AlbumFragment.OnAlbumClickListener() {
        @Override
        public void onAlbumClick(@Dvr.DvrFolder int folder) {
            mFolderType = folder;
            mShowingThumbnail = true;
            hideAlbumFragment();
            showThumbnailFragment(folder);
        }
    };

    /** Private methods to update UI */

    private void showThumbnailFragment(@Dvr.DvrFolder int folder) {
        if (mThumbnailFragment == null) {
            mThumbnailFragment = ThumbnailFragment.newInstance(folder);
            mFm.beginTransaction().add(R.id.contentFragmentContainer, mThumbnailFragment).commit();
        }

        mFm.beginTransaction().show(mThumbnailFragment).commit();
    }

    private void hideThumbnailFragment() {
        if (mThumbnailFragment != null) {
            mFm.beginTransaction().hide(mThumbnailFragment).commit();
        }
    }

    private void showAlbumFragment() {
        if (mAlbumFragment == null) {
            mAlbumFragment = new AlbumFragment();
            mAlbumFragment.setOnAlbumClickListener(mOnAlbumClickListener);
            mFm.beginTransaction().add(R.id.contentFragmentContainer, mAlbumFragment).commit();
        }

        mFm.beginTransaction().show(mAlbumFragment).commit();
    }

    private void hideAlbumFragment() {
        if (mAlbumFragment != null) {
            mFm.beginTransaction().hide(mAlbumFragment).commit();
        }
    }
}