JSONArray到ListView数组数据未显示

Question

i want to when run the app make the jsonRequest without pressing any button and save the data. i just add a method for internet connection check:

if the connection to the internet its true, make the json request pass to the spinner, and save de data.

and when the internet connection its false, just load the data from sharedPreferences to the spinner.

The application runs totally fine with the buttons (with simple onClick methods) and without the verificaConexion method.

But when i remove the buttons, add the verificaConexion method and i have internet connection, just, make the json request, show the data in the spinner and not save the data And when I close the app, remove the wifi, open the app, the spinner shows nothing.

For any reason the methods save and load data doesn't works.

This is my onCreate()

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

    btnObtener = (Button) findViewById(R.id.btnObtener);
    spDelegaciones = (Spinner)findViewById(R.id.spDelegaciones);
    btnGuardar = (Button) findViewById(R.id.btnGuardar);
    btnCargar = (Button) findViewById(R.id.btnCargar);
    txJsonArray = (TextView) findViewById(R.id.txJsonArray);

    verificaConexion(this);

}

This is my json Request method, works fine:

public void request() {
        JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(json_url,
                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray jsonArray) {
                        Log.e("jsonArray", "" + jsonArray);
                        if (jsonArray == null) {
                            Toast.makeText(MainActivity.this, "EL JSONArray esta VACIO !!! ", Toast.LENGTH_SHORT).show();
                        } else {

                            for (int i = 0; i < jsonArray.length(); i++) {

                                try {
                                    JSONObject jsonObject = jsonArray.getJSONObject(i);
                                    //con el php JsonArrayRequest2.php
                                    // String contact = jsonObject.getString("delegacion");
                                    //con el php JsonArrayVariosCampos.php
                                    String contact = jsonObject.getString("Delegacion");
                                    arrayList.add(contact);


                                } catch (JSONException e) {
                                    e.printStackTrace();
                                }
                            }

                            adapter.notifyDataSetChanged();
                        }

                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

                Toast.makeText(MainActivity.this, "ERROR...", Toast.LENGTH_SHORT).show();
                error.printStackTrace();
            }
        });
        RequestQueue requestQueue = Volley.newRequestQueue(MainActivity.this);
        requestQueue.add(jsonArrayRequest);

}

my guardarDatos method to save the data:

 public boolean guardarDatos(){

    SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(this);
    SharedPreferences.Editor mEdit1 = sp.edit();
/* sKey is an array */
    mEdit1.putInt("Status_size", arrayList.size());

    for(int i=0;i<arrayList.size();i++)
    {
        mEdit1.remove("Status_" + i);
        mEdit1.putString("Status_" + i, arrayList.get(i));
    }

    Toast.makeText(MainActivity.this, " DATOS GUARDADOS ", Toast.LENGTH_SHORT).show();

    return mEdit1.commit();



}

and my cargarDatos method to load the data:

public void cargarDatos(){

    SharedPreferences mSharedPreference1 =   PreferenceManager.getDefaultSharedPreferences(this);
    arrayList.clear();
    int size = mSharedPreference1.getInt("Status_size", 0);

    for(int i=0;i<size;i++)
    {
        arrayList.add(mSharedPreference1.getString("Status_" + i, null));
    }


    adapter = new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, arrayList);
    spDelegaciones.setAdapter(adapter);

    Toast.makeText(MainActivity.this, " DATOS CARGADOS ", Toast.LENGTH_SHORT).show();

}

and here is my class to check the internet connection:

public boolean verificaConexion(Context ctx){
    boolean bConectado = false;
    ConnectivityManager connec = (ConnectivityManager) ctx.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo[] redes = connec.getAllNetworkInfo();
    for (int i = 0; i < 2; i++) {
        if (redes[i].getState() == NetworkInfo.State.CONNECTED) {
           bConectado = true;
            if(bConectado) {
                Toast.makeText(MainActivity.this, " con conexion ", Toast.LENGTH_LONG).show();

                adapter = new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, arrayList);
                spDelegaciones.setAdapter(adapter);
                request();
                guardarDatos();

            }else {

                cargarDatos();
            }

        }else{




        }


    }
    return bConectado;

}

Answer 1

Since you are using only one string in contact class. instead of arrayList<Contact> I will use ArrayList<String>

here I have removed singleTone class. and added jsonArrayRequest code inside in same class. and after adding item in arraylist I have called adapter.notifyDataSetChanged();

MainActivity.class

public class MainActivity extends AppCompatActivity {

    TextView txdeleg_lista;
    Button btnObtener;
    ArrayList<String> arrayList = new ArrayList<String>();
    ListView listView;
    String json_url = "your url";
    ArrayAdapter<String> adapter;

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

    btnObtener = (Button) findViewById(R.id.btnObtener);
    txdeleg_lista = (TextView) findViewById(R.id.txdeleg_lista);
    listView = (ListView) findViewById(R.id.lvDelegacion);

    adapter = new ArrayAdapter<String>(MainActivity.this, android.R.layout.simple_list_item_1, arrayList);

    btnObtener.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //startActivity(new Intent(MainActivity.this, DesplegarLista.class));

            listView.setAdapter(adapter);


            request();

        }
    });
  }

  public void request() {
    JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(json_url,
            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(JSONArray jsonArray) {
                    Log.e("jsonArray",""+jsonArray);
                    if(jsonArray == null){
                        Toast.makeText(MainActivity.this,"EL JSONArray esta VACIO !!! ", Toast.LENGTH_SHORT).show();
                    }
                    else {

                        for (int i = 0; i < jsonArray.length(); i++) {

                            try {
                                JSONObject jsonObject = jsonArray.getJSONObject(i);
                                String contact = jsonObject.getString("UFULLNAME");
                                arrayList.add(contact);


                            } catch (JSONException e) {
                                e.printStackTrace();
                            }
                        }

                        adapter.notifyDataSetChanged();
                    }

                }
            }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {

            Toast.makeText(MainActivity.this,"ERROR...", Toast.LENGTH_SHORT).show();
            error.printStackTrace();
        }
    });
    RequestQueue requestQueue = Volley.newRequestQueue(MainActivity.this);
    requestQueue.add(jsonArrayRequest);
    }
}

check and if you have any query comment.