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Я пытаюсь заполнить recyclerview из задачи async. и в задаче Async данные извлекаются через вызов API и помещаются в таблицу SQLite, тогда список заполняется из таблицы SQLite. Список не отображается при первой загрузке. Но когда я закрываю приложение и снова открываю приложение, список заполняется. Это общая проблема, которую нужно решать должным образом или мне не хватает чего-то еще?Recyclerview из SQLite отображает пустую страницу в первый раз
public class KingsActivity extends AppCompatActivity {
RecyclerView mRecyclerView;
RecyclerView.Adapter mAdapter;
RecyclerView.LayoutManager mLayoutManager;
List<King> kingList=new ArrayList<King>();
@Override
protected void onCreate(Bundle savedInstanceState) {
Log.d("method_track","onCreate");
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//To avoid the load on the main thread
new DownloadDataAsync().execute(this);
}
public class DownloadDataAsync extends AsyncTask<Context, Integer, Context> {
@Override
protected Context doInBackground(Context... ctx) {
downloadData(ctx[0]);
return ctx[0];
}
@Override
protected void onProgressUpdate(Integer... progress) {
}
@Override
protected void onPostExecute(Context result) {
Log.d("method_track","PostExecute");
Cursor kingsRows=DatabaseHelper.getInstance(result.getApplicationContext()).getData(DatabaseHelper.TABLE_WESTEROS_KINGS);
kingsRows.moveToFirst();
while(kingsRows.moveToNext()){
String kingName=kingsRows.getString(kingsRows.getColumnIndex(DatabaseHelper.KEY_WESTEROS_KINGS_NAME));
int battleCount=kingsRows.getInt(kingsRows.getColumnIndex(DatabaseHelper.KEY_WESTEROS_KINGS_BATTLE_COUNT));
int rating=kingsRows.getInt(kingsRows.getColumnIndex(DatabaseHelper.KEY_WESTEROS_KINGS_RATING));
kingList.add(new King(kingName,rating,battleCount));
}
kingsRows.close();
mRecyclerView = (RecyclerView)findViewById(R.id.my_recycler_view);
mLayoutManager = new LinearLayoutManager(result);
mRecyclerView.setLayoutManager(mLayoutManager);
mAdapter = new KingsAdapterRC(kingList,result);
mRecyclerView.setAdapter(mAdapter);
mAdapter.notifyDataSetChanged();
}
public void downloadData(final Context ctx){
// Get a RequestQueue
RequestQueue queue = HttpRequestHandler.getInstance(ctx.getApplicationContext()).
getRequestQueue();
String url ="http://starlord.hackerearth.com/gotjson";
// Request a string response from the provided URL.
StringRequest stringRequest = new StringRequest(Request.Method.GET, url,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
// Display the first 500 characters of the response string.
//Log.d("result_check",response.substring(0,500));
loadToDb(response,ctx);
populateList(ctx);
calculateRating(ctx);
logRatings(ctx);
//mTextView.setText("Response is: "+ response.substring(0,500));
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.d("result_check","Error");
//mTextView.setText("That didn't work!");
}
});
// Add a request to RequestQueue.
HttpRequestHandler.getInstance(ctx).addToRequestQueue(stringRequest);
}
protected void loadToDb(String jsonResponse,Context ctx){
DatabaseHelper.getInstance(ctx.getApplicationContext()).truncate(DatabaseHelper.TABLE_WESTEROS_DATA);
try {
JSONArray jsonArray = new JSONArray(jsonResponse);
for(int i=0;i<jsonArray.length();i++){
JSONObject jsonObj = (JSONObject)jsonArray.get(i);
Iterator<String> iter = jsonObj.keys();
HashMap<String,String> fieldVales=new HashMap<String, String>();
while (iter.hasNext()) {
String key = iter.next();
try {
Object value = jsonObj.get(key);
fieldVales.put(key,value.toString());
} catch (JSONException e) {
// Something went wrong!
Log.e("loadTodb",e.toString());
}
}
DatabaseHelper.getInstance(ctx.getApplicationContext()).insert(DatabaseHelper.TABLE_WESTEROS_DATA,fieldVales);
}
} catch (Throwable t) {
//Log.e("My App", "Could not parse malformed JSON: \"" + json + "\"");
}
}
protected void populateList(Context ctx){
List<King> kingList=new ArrayList<King>();
String[] kings;
int kingsCount=0;
String sql="SELECT DISTINCT "+DatabaseHelper.KEY_WESTEROS_ATTACKER_KING+ " FROM "+ DatabaseHelper.TABLE_WESTEROS_DATA
+" WHERE "+ DatabaseHelper.KEY_WESTEROS_ATTACKER_KING +" <> ''";
Cursor rows=DatabaseHelper.getInstance(ctx.getApplicationContext()).getReadableDatabase().rawQuery(sql, null);
kingsCount+=rows.getCount();
String sql2="SELECT DISTINCT "+DatabaseHelper.KEY_WESTEROS_DEFENDER_KING + " FROM "+ DatabaseHelper.TABLE_WESTEROS_DATA
+ " WHERE "+ DatabaseHelper.KEY_WESTEROS_DEFENDER_KING + " NOT IN ("+sql+ ") AND "
+ DatabaseHelper.KEY_WESTEROS_DEFENDER_KING +" <> ''";
Cursor rows2=DatabaseHelper.getInstance(ctx.getApplicationContext()).getReadableDatabase().rawQuery(sql2, null);
kingsCount+=rows2.getCount();
kings=new String[kingsCount];
int i=0;
if (rows.moveToFirst()) {
while (!rows.isAfterLast()) {
//your code to implement
kings[i]=rows.getString(rows.getColumnIndex(DatabaseHelper.KEY_WESTEROS_ATTACKER_KING));
i++;
rows.moveToNext();
}
}
rows.close();
if (rows2.moveToFirst()) {
while (!rows2.isAfterLast()) {
//your code to implement
kings[i]=rows2.getString(rows2.getColumnIndex(DatabaseHelper.KEY_WESTEROS_DEFENDER_KING));
i++;
rows2.moveToNext();
}
}
rows2.close();
DatabaseHelper.getInstance(ctx.getApplicationContext()).truncate(DatabaseHelper.TABLE_WESTEROS_KINGS);
for(i=0;i<kingsCount;i++){
HashMap<String,String> fieldValues=new HashMap<String, String>();
fieldValues.put(DatabaseHelper.KEY_WESTEROS_KINGS_NAME,kings[i]);
fieldValues.put(DatabaseHelper.KEY_WESTEROS_KINGS_RATING,"400");
fieldValues.put(DatabaseHelper.KEY_WESTEROS_KINGS_BATTLE_COUNT,"0");
DatabaseHelper.getInstance(ctx.getApplicationContext()).insert(DatabaseHelper.TABLE_WESTEROS_KINGS,fieldValues);
}
}
protected void calculateRating(Context ctx){
Cursor battles_cur=DatabaseHelper.getInstance(ctx.getApplicationContext()).getData(DatabaseHelper.TABLE_WESTEROS_DATA);
if(battles_cur.moveToFirst()){
while(!battles_cur.isAfterLast()){
String attackingKing=battles_cur.getString(battles_cur.getColumnIndex(DatabaseHelper.KEY_WESTEROS_ATTACKER_KING));
String defendingKing=battles_cur.getString(battles_cur.getColumnIndex(DatabaseHelper.KEY_WESTEROS_DEFENDER_KING));
if(!attackingKing.equals("") && !defendingKing.equals("")){
HashMap<String,String> whereConDfk=new HashMap<String,String>();
whereConDfk.put(DatabaseHelper.KEY_WESTEROS_KINGS_NAME,defendingKing);
Cursor cursor1=DatabaseHelper.getInstance(ctx.getApplicationContext()).getData(DatabaseHelper.TABLE_WESTEROS_KINGS,whereConDfk);
double defKing_rating;
double defKing_battleCount;
if(cursor1.moveToFirst()){
defKing_rating=cursor1.getDouble(cursor1.getColumnIndex(DatabaseHelper.KEY_WESTEROS_KINGS_RATING));
defKing_battleCount=cursor1.getDouble(cursor1.getColumnIndex(DatabaseHelper.KEY_WESTEROS_KINGS_BATTLE_COUNT));
cursor1.close();
HashMap<String,String> whereConAtk=new HashMap<String,String>();
whereConAtk.put(DatabaseHelper.KEY_WESTEROS_KINGS_NAME,attackingKing);
Cursor cursor2=DatabaseHelper.getInstance(ctx.getApplicationContext()).getData(DatabaseHelper.TABLE_WESTEROS_KINGS,whereConAtk);
Double atkKing_rating;
Double atkKing_battleCount;
if(cursor2.moveToFirst()){
atkKing_rating=cursor2.getDouble(cursor2.getColumnIndex(DatabaseHelper.KEY_WESTEROS_KINGS_RATING));
atkKing_battleCount=cursor2.getDouble(cursor2.getColumnIndex(DatabaseHelper.KEY_WESTEROS_KINGS_BATTLE_COUNT));
cursor2.close();
atkKing_battleCount++;
defKing_battleCount++;
Double defKing_rating_tr=Math.pow(10,(defKing_rating/400));
Double atkKing_rating_tr=Math.pow(10,(atkKing_rating/400));
Double defKing_rating_ex=defKing_rating_tr/(defKing_rating_tr+atkKing_rating_tr);
Double atkKing_rating_ex=atkKing_rating_tr/(defKing_rating_tr+atkKing_rating_tr);
String attackerStatus=battles_cur.getString(battles_cur.getColumnIndex(DatabaseHelper.KEY_WESTEROS_ATTACKER_OUTCOME));
Double atkKing_rating_new=atkKing_rating;
Double defKing_rating_new=defKing_rating;
if(attackerStatus.equals("win")){
atkKing_rating_new=atkKing_rating+(32*(1-atkKing_rating_ex));
defKing_rating_new=defKing_rating+(32*(0-defKing_rating_ex));
}else if(attackerStatus.equals("loss")){
atkKing_rating_new=atkKing_rating+(32*(0-atkKing_rating_ex));
defKing_rating_new=defKing_rating+(32*(1-defKing_rating_ex));
}else if(attackerStatus.equals("draw")){
atkKing_rating_new=atkKing_rating+(32*(0.5-atkKing_rating_ex));
defKing_rating_new=defKing_rating+(32*(0.5-defKing_rating_ex));
}
String update_atkKing_ratingQuery="UPDATE "+ DatabaseHelper.TABLE_WESTEROS_KINGS + " SET "
+ DatabaseHelper.KEY_WESTEROS_KINGS_RATING+" = "+atkKing_rating_new+", "
+ DatabaseHelper.KEY_WESTEROS_KINGS_BATTLE_COUNT+" = "+atkKing_battleCount
+ " WHERE "+ DatabaseHelper.KEY_WESTEROS_KINGS_NAME +" =\""+attackingKing+"\"";
String update_defKing_ratingQuery="UPDATE "+ DatabaseHelper.TABLE_WESTEROS_KINGS + " SET "
+ DatabaseHelper.KEY_WESTEROS_KINGS_RATING+" = "+defKing_rating_new+", "
+ DatabaseHelper.KEY_WESTEROS_KINGS_BATTLE_COUNT+" = "+defKing_battleCount
+ " WHERE "+ DatabaseHelper.KEY_WESTEROS_KINGS_NAME +" =\""+defendingKing+"\"";
DatabaseHelper.getInstance(ctx.getApplicationContext()).getWritableDatabase().execSQL(update_atkKing_ratingQuery);
DatabaseHelper.getInstance(ctx.getApplicationContext()).getWritableDatabase().execSQL(update_defKing_ratingQuery);
}
}
}
battles_cur.moveToNext();
}
}
}
protected void logRatings(Context ctx){
Log.d("method_track","logratings");
Cursor kings_cur=DatabaseHelper.getInstance(ctx.getApplicationContext()).getData(DatabaseHelper.TABLE_WESTEROS_KINGS);
try {
while (kings_cur.moveToNext()) {
String name=kings_cur.getString(kings_cur.getColumnIndex(DatabaseHelper.KEY_WESTEROS_KINGS_NAME));
String rating=kings_cur.getString(kings_cur.getColumnIndex(DatabaseHelper.KEY_WESTEROS_KINGS_RATING));
String battleCount=kings_cur.getString(kings_cur.getColumnIndex(DatabaseHelper.KEY_WESTEROS_KINGS_BATTLE_COUNT));
//Log.d("method_track", "logratings");
Log.d("rating_inspect",name+" - "+rating+" - "+battleCount);
}
}finally {
kings_cur.close();
}
}
}
}
отладка вашего приложения .. это покажет вам, что именно происходит в первый раз .... попробуйте удалить mAdapter.notifyDataSetChanged(); – kgandroid
dont Intialize your recycler view in onPostExecute сделать это перед вызовом asynch-задачи и обновить список адаптеров, вызвав notifyDataSetChange, как только вы получите список из asynch-задачи i, e внутри onPostExecute –