Android Java; ¿Cómo puedo analizar un archivo JSON local de la carpeta de activos en un ListView

Actualmente estoy desarrollando una aplicación de física que se supone que muestra una lista de fórmulas e incluso resuelve algunas de ellas (el único problema es el ListView )

Este es mi diseño principal

Y esta es mi actividad principal

 package com.wildsushii.quickphysics; import java.io.IOException; import java.io.InputStream; import java.util.ArrayList; import java.util.HashMap; import org.json.JSONException; import org.json.JSONObject; import android.os.Bundle; import android.app.Activity; import android.content.Context; import android.content.res.AssetManager; import android.view.Menu; import android.widget.ListView; public class CatList extends Activity { public static String AssetJSONFile (String filename, Context context) throws IOException { AssetManager manager = context.getAssets(); InputStream file = manager.open(filename); byte[] formArray = new byte[file.available()]; file.read(formArray); file.close(); return new String(formArray); } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_cat_list); ListView categoriesL = (ListView)findViewById(R.id.listFormulas); ArrayList<HashMap> formList = new ArrayList<HashMap>(); Context context = null; try { String jsonLocation = AssetJSONFile("formules.json", context); JSONObject formArray = (new JSONObject()).getJSONObject("formules"); String formule = formArray.getString("formule"); String url = formArray.getString("url"); } catch (IOException e) { e.printStackTrace(); } catch (JSONException e) { e.printStackTrace(); } //My problem is here!! } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.cat_list, menu); return true; } } 

De hecho, sé que puedo hacer esto sin usar JSON, pero necesito más práctica para analizar JSON. Por cierto, este es el JSON

  { "formules": [ { "formule": "Linear Motion", "url": "qp1" }, { "formule": "Constant Acceleration Motion", "url": "qp2" }, { "formule": "Projectile Motion", "url": "qp3" }, { "formule": "Force", "url": "qp4" }, { "formule": "Work, Power, Energy", "url": "qp5" }, { "formule": "Rotary Motion", "url": "qp6" }, { "formule": "Harmonic Motion", "url": "qp7" }, { "formule": "Gravity", "url": "qp8" }, { "formule": "Lateral and Longitudinal Waves", "url": "qp9" }, { "formule": "Sound Waves", "url": "qp10" }, { "formule": "Electrostatics", "url": "qp11" }, { "formule": "Direct Current", "url": "qp12" }, { "formule": "Magnetic Field", "url": "qp13" }, { "formule": "Alternating Current", "url": "qp14" }, { "formule": "Thermodynamics", "url": "qp15" }, { "formule": "Hydrogen Atom", "url": "qp16" }, { "formule": "Optics", "url": "qp17" }, { "formule": "Modern Physics", "url": "qp18" }, { "formule": "Hydrostatics", "url": "qp19" }, { "formule": "Astronomy", "url": "qp20" } ] } 

He intentado muchas cosas e incluso he eliminado todo el proyecto para hacer uno nuevo 🙁

 public String loadJSONFromAsset() { String json = null; try { InputStream is = getActivity().getAssets().open("yourfilename.json"); int size = is.available(); byte[] buffer = new byte[size]; is.read(buffer); is.close(); json = new String(buffer, "UTF-8"); } catch (IOException ex) { ex.printStackTrace(); return null; } return json; } 

  try { JSONObject obj = new JSONObject(loadJSONFromAsset()); JSONArray m_jArry = obj.getJSONArray("formules"); ArrayList> formList = new ArrayList>(); HashMap m_li; for (int i = 0; i < m_jArry.length(); i++) { JSONObject jo_inside = m_jArry.getJSONObject(i); Log.d("Details-->", jo_inside.getString("formule")); String formula_value = jo_inside.getString("formule"); String url_value = jo_inside.getString("url"); //Add your values in your `ArrayList` as below: m_li = new HashMap(); m_li.put("formule", formula_value); m_li.put("url", url_value); formList.add(m_li); } } catch (JSONException e) { e.printStackTrace(); } 

 { // json object node "formules": [ // json array formules { // json object "formule": "Linear Motion", // string "url": "qp1" } 

  Context context = null; // context is null try { String jsonLocation = AssetJSONFile("formules.json", context); 

  try { String jsonLocation = AssetJSONFile("formules.json", CatList.this); 

 try { String jsonLocation = AssetJSONFile("formules.json", context); JSONObject jsonobject = new JSONObject(jsonLocation); JSONArray jarray = (JSONArray) jsonobject.getJSONArray("formules"); for(int i=0;i 

 public static String getAssetJsonData(Context context) { String json = null; try { InputStream is = context.getAssets().open("myJson.json"); int size = is.available(); byte[] buffer = new byte[size]; is.read(buffer); is.close(); json = new String(buffer, "UTF-8"); } catch (IOException ex) { ex.printStackTrace(); return null; } Log.e("data", json); return json; } 

 String data = getAssetJsonData(getApplicationContext()); Type type = new TypeToken() { }.getType();  modelObject = new Gson().fromJson(data, type);