java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT

Question

Can you help me to solving this error? Where is the problem?

private final String TAG = "MulaiUjian";
private RecyclerView recyclerView;
private LinearLayoutManager layoutManager;
private RecycleViewAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_mulai_ujian);
    recyclerView = (RecyclerView)findViewById(R.id.recycle_txtSoal);
    layoutManager = new LinearLayoutManager(MulaiUjian.this);
    recyclerView.setLayoutManager(layoutManager);
    requestJsonObject();

    Toolbar toolbar = (Toolbar)findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    if(getSupportActionBar()!=null){
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setDisplayShowHomeEnabled(true);
    }
}
private void requestJsonObject(){
    RequestQueue queue = Volley.newRequestQueue(this);
    String url ="https://www.rootorial.com/worthit2/resgister/showalluser.php";
    StringRequest stringRequest = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() {
        @Override
        public void onResponse(String response) {
            Log.d(TAG, "Response " + response);
            GsonBuilder builder = new GsonBuilder();
            Gson mGson = builder.create();
            List<ItemObject> posts = new ArrayList<ItemObject>();
            posts = Arrays.asList(mGson.fromJson(response, ItemObject[].class));
            adapter = new RecycleViewAdapter(MulaiUjian.this, posts);
            recyclerView.setAdapter(adapter);
        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            Log.d(TAG, "Error " + error.getMessage());
        }
    });
    queue.add(stringRequest);
}

Stacktrace:

Process: com.example.root.pmb, PID: 7806 **com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2 path $** at com.google.gson.Gson.fromJson(Gson.java:826) at com.google.gson.Gson.fromJson(Gson.java:779) at com.google.gson.Gson.fromJson(Gson.java:728) at com.google.gson.Gson.fromJson(Gson.java:700) at com.example.root.pmb.MulaiUjian$1.onResponse(MulaiUjian.java:59) at com.example.root.pmb.MulaiUjian$1.onResponse(MulaiUjian.java:52) at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:60) at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:30) at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5268) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697) Caused by: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2 path $ at com.google.gson.stream.JsonReader.beginArray(JsonReader.java:350) at com.google.gson.internal.bind.ArrayTypeAdapter.read(ArrayTypeAdapter.java:70) at com.google.gson.Gson.fromJson(Gson.java:814) at com.google.gson.Gson.fromJson(Gson.java:779)  at com.google.gson.Gson.fromJson(Gson.java:728)  at com.google.gson.Gson.fromJson(Gson.java:700)  at com.example.root.pmb.MulaiUjian$1.onResponse(MulaiUjian.java:59)  at com.example.root.pmb.MulaiUjian$1.onResponse(MulaiUjian.java:52)  at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:60)  at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:30)  at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99)  at android.os.Handler.handleCallback(Handler.java:739)  at android.os.Handler.dispatchMessage(Handler.java:95)  at android.os.Looper.loop(Looper.java:135)  at android.app.ActivityThread.main(ActivityThread.java:5268)  at java.lang.reflect.Method.invoke(Native Method)  at java.lang.reflect.Method.invoke(Method.java:372)  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697)

Answer 1

You probably need to check your models or the response you are receiving. You are using ItemObject[].class) but might be expecting an object so deserialization is failing.

Answer 2

The problem is that, your whole JSON response is a JSONObject if see it carefully.

{
    "id_soal": [{
        "id_soal": "So0045",
        "isi_soal": "Pemilihan Umum tahun 1999 diikuti oleh:",
        "bobot_nilai": "1",
        "jawab_a": "10 partai politik",
        "jawab_b": "18 partai politik",
        "jawab_c": "45 partai politik",
        "jawab_d": "48 partai politik",
        "jawaban_benar": "D"
    }, {
        "id_soal": "So0039",
        "isi_soal": "Prinsup Pembangunan Berkelanjutan adalah :",
        "bobot_nilai": "1",
        "jawab_a": "Pembangunan terus menerus",
        "jawab_b": "Pembangunan yang tidak merusak lingkungan",
        "jawab_c": "Pembangunan yang mempertimbangkan kehidupan generasiyang akan datang",
        "jawab_d": "Pembangunan yang sesuai rencana pemerintah",
        "jawaban_benar": "C"
    }, {
        "id_soal": "So0065",
        "isi_soal": "Dimanakah tempat dibacakan naskah Proklamasi Indonesia ?",
        "bobot_nilai": "1",
        "jawab_a": "Jl. Diponogoro No. 56",
        "jawab_b": "Jl. Pegangsaan timur No. 56",
        "jawab_c": "Jl. Teuku Umar No. 67",
        "jawab_d": "Jl. Cokroaminoto No. 67",
        "jawaban_benar": "B"
    }
}

and for Gson to parse your Response Successfully you need to need to Have two model class like below

public class ItemObject {

    private List<IdSoal> id_soal = null;
    private Integer success;
    private Map<String, Object> additionalProperties = new HashMap<String, Object>();

    public List<IdSoal> getIdSoal() {
        return id_soal;
    }

    public void setIdSoal(List<IdSoal> idSoal) {
        this.id_soal = idSoal;
    }

    public Integer getSuccess() {
        return success;
    }

    public void setSuccess(Integer success) {
        this.success = success;
    }

}

and,

public class IdSoal {

    private String id_soal;
    private String isi_soal;
    private String bobot_nilai;
    private String jawab_a;
    private String jawab_b;
    private String jawab_c;
    private String jawab_d;
    private String jawaban_benar;
    private Map<String, Object> additionalProperties = new HashMap<String, Object>();

    public String getId_soal() {
        return id_soal;
    }

    public void setId_soal(String id_soal) {
        this.id_soal = id_soal;
    }

    public String getIsi_soal() {
        return isi_soal;
    }

    public void setIsi_soal(String isi_soal) {
        this.isi_soal = isi_soal;
    }

    public String getBobot_nilai() {
        return bobot_nilai;
    }

    public void setBobot_nilai(String bobot_nilai) {
        this.bobot_nilai = bobot_nilai;
    }

    public String getJawab_a() {
        return jawab_a;
    }

    public void setJawab_a(String jawab_a) {
        this.jawab_a = jawab_a;
    }

    public String getJawab_b() {
        return jawab_b;
    }

    public void setJawab_b(String jawab_b) {
        this.jawab_b = jawab_b;
    }

    public String getJawab_c() {
        return jawab_c;
    }

    public void setJawab_c(String jawab_c) {
        this.jawab_c = jawab_c;
    }

    public String getJawab_d() {
        return jawab_d;
    }

    public void setJawab_d(String jawab_d) {
        this.jawab_d = jawab_d;
    }

    public String getJawaban_benar() {
        return jawaban_benar;
    }

    public void setJawaban_benar(String jawaban_benar) {
        this.jawaban_benar = jawaban_benar;
    }
}

then all you need to do is like this

ItemObject itemObject = mGson.fromJson(response, ItemObject.class));