java.lang.illegalstateexception预期为begin_array，但在第1行第1列路径处是字符串$

Question

/公共类MainActivity扩展了AppCompatActivity {

    private RecyclerView recyclerview;
    private RecyclerView.LayoutManager layoutmanager;
    private List<Potrawy> potrawy;
    private Adapter adapter;
    private ApiInterface apiinterface;
    ProgressBar progressBar;

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

        progressBar = findViewById(R.id.progress);
        recyclerview = findViewById(R.id.recycler);
        layoutmanager = new LinearLayoutManager(this);
        recyclerview.setLayoutManager(layoutmanager);
        recyclerview.setHasFixedSize(true);

        fetchPotrawy(""); // without keyword
    }



    public void fetchPotrawy(String key){
        apiinterface = ApiClient.getApiClient().create(ApiInterface.class);
        Call<List<Potrawy>> call = apiinterface.getPotrawy(key);

        call.enqueue(new Callback<List<Potrawy>>() {
            @Override
            public void onResponse(Call<List<Potrawy>> call, Response<List<Potrawy>> response) {
                progressBar.setVisibility(View.GONE);
                potrawy = response.body();
                adapter = new Adapter(potrawy, MainActivity.this);
                recyclerview.setAdapter(adapter);
                adapter.notifyDataSetChanged();
            }

            @Override
            public void onFailure(Call<List<Potrawy>> call, Throwable t) {
                progressBar.setVisibility(View.GONE);
                Toast.makeText(MainActivity.this, "Error on: " + t.toString(), Toast.LENGTH_SHORT).show();
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.menu, menu);

        SearchManager searchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE);
        SearchView searchView = (SearchView) menu.findItem(R.id.search).getActionView();

        searchView.setSearchableInfo(
                searchManager.getSearchableInfo(getComponentName())
        );

        searchView.setIconifiedByDefault(false);
        searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
            @Override
            public boolean onQueryTextSubmit(String query) {
                fetchPotrawy(query);

                return false;
            }

            @Override
            public boolean onQueryTextChange(String newText) {
                fetchPotrawy(newText);

                return false;
            }
        });

        return true;
    }

/     公共课Potrawy {

    @SerializedName("id") private int id;
    @SerializedName("nazwa") private String nazwa;
    @SerializedName("keywords") private String keywords;

    public int getId() {
        return id;
    }

    public String getNazwa() {
        return nazwa;
    }

    public String getKeywords() {
        return keywords;
    }
}

/     公共接口ApiInterface {

    @GET("getPotrawy.php")
    Call<List<Potrawy>> getPotrawy (@Query("key") String keyword);

}

/     公共类ApiClient {

    public static final String BASE_URL = "http://localhost/inz/";
    public static Retrofit retrofit;

    public static Retrofit getApiClient(){

        if(retrofit==null)
        {
            Gson gson = new GsonBuilder()
                    .setLenient()
                    .create();

            retrofit = new Retrofit.Builder()
                    .baseUrl(BASE_URL)
                    .addConverterFactory(GsonConverterFactory.create(gson))
                    .build();
        }
        return retrofit;
    }
}

/公共类Adapter扩展了RecyclerView.Adapter {

    private List<Potrawy> potrawy;
    private Context context;

    public Adapter(List<Potrawy> potrawy, Context context) {
        this.potrawy = potrawy;
        this.context = context;
    }

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item, parent, false);

        return new MyViewHolder(view);
    }

    @Override
    public void onBindViewHolder( MyViewHolder holder, int position) {

        holder.nazwa.setText(potrawy.get(position).getNazwa());

    }

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

    public static class MyViewHolder extends RecyclerView.ViewHolder {

        TextView nazwa;

        public MyViewHolder(@NonNull View itemView) {
            super(itemView);

            nazwa = itemView.findViewById(R.id.nazwa);
        }
    }

我该如何解决？没有一个stackoverflow线程可以帮助我。 问题名称在主题中 java.lang.illegalstateexception预期为begin_array，但在第1行第1列路径$

处为字符串