Fragment cast error

public static final String LIST_FRAGMENT = "list_fragment";
public static final String VIEWPAGER_FRAGMENT = "viewpager_fragment";

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

    ArrayList<String> al ,al2 ;
    al = new ArrayList<String>();
    al2 = new ArrayList<String>();
    System.out.println("Initial size of al: " + al.size());

    // add elements to the array list
    al.add("C");
    al.add("A");
    al.add("E");
    al.add("B");
    al.add("C");
    al.add("A");
    al.add("E");
    al.add("B");

    al2.add("C");
    al2.add("A");
    al2.add("E");
    al2.add("B");
    al2.add("C");
    al2.add("A");
    al2.add("E");
    al2.add("B");
    Recipes.setList(al); // set list
    Recipes.setList2(al2); // set list

    BlankFragment savedFragment = (BlankFragment) getSupportFragmentManager()
            .findFragmentByTag(LIST_FRAGMENT);
    if (savedFragment == null) {
        BlankFragment fragment = new BlankFragment();
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.add(R.id.placeHolder, fragment, LIST_FRAGMENT);
        fragmentTransaction.commit();
    }
}

@Override
public void onListRecipeSelected(int position) {

}

public static final String LIST_FRAGMENT = "list_fragment";
private View mView;


@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    mView = inflater.inflate(R.layout.fragment_blank, container, false);
    start();
    return mView;
}

private void start() {

    FragmentManager fragmentManager =getFragmentManager();

    ListFragment savedFragment = (ListFragment)
            fragmentManager.findFragmentByTag(LIST_FRAGMENT);
    if (savedFragment == null) {
        ListFragment fragment = new ListFragment();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.add(R.id.fragment_blank, fragment, LIST_FRAGMENT);
        fragmentTransaction.commit();
    }
}


@Override
public void onListRecipeSelected(int position) {

}

public interface OnRecipeSelectedInterface {
    void onListRecipeSelected(int position);
}

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    OnRecipeSelectedInterface listener = (OnRecipeSelectedInterface) getActivity();
    View view = inflater.inflate(R.layout.fragment_list, container, false);

    RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.listRecyclerView);
    ListAdapter listAdapter = new ListAdapter(listener);
    recyclerView.setAdapter(listAdapter);
    RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getActivity());
    recyclerView.setLayoutManager(layoutManager);

    return view;
}

public ListAdapter(ListFragment.OnRecipeSelectedInterface listener) {
    this.mListener = listener;
}

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = LayoutInflater
            .from(parent.getContext())
            .inflate(R.layout.list_item, parent, false);
    return new ListViewHolder(view);
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    ((ListViewHolder) holder).bindView(position);
}

@Override
public int getItemCount() {
    return Recipes.list.size();
}

private class ListViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

    private TextView mTextView2;
    private TextView mTextView;
    private int mPosition;

    public ListViewHolder(View itemView) {
        super(itemView);
        mTextView2 = (TextView) itemView.findViewById(R.id.itemText2);
        mTextView = (TextView) itemView.findViewById(R.id.itemText);
        itemView.setOnClickListener(this);
    }

    public void bindView(int position) {
        mTextView2.setText(Recipes.list2.get(position));;
        mTextView.setText(Recipes.list.get(position));
        mPosition = position;
    }

    @Override
    public void onClick(View v) {
        mListener.onListRecipeSelected(mPosition);
    }
}