Develop Reference

RecyclerView not loading

I have created a Recycler view that is supposed to be created when the activity is created. Currently, when I click a button on my MainActivity, an intent launches the ListActivity which has my recyclerview but it doesn't load. I have used toast message to confirm that each method is getting called, and that I am getting the correct data from the API. If I reset the activity using the restart activity option in Android Studio the Recycler shows up and functions correctly. I don't know what I'm doing wrong.
Here is my ListActivity:
private RecyclerView myrecyclerview;
private RecyclerView.Adapter myadapter;
private RecyclerView.LayoutManager mylayoutmanager;
static RequestQueue listqueue;
static final private String url = "https://swapi.dev/api/people/";
static ArrayList<RecyclerItem> list = new ArrayList<>();
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
getSupportActionBar().hide();
listqueue = Volley.newRequestQueue(this);
myrecyclerview = findViewById(R.id.characterlist);
myadapter = new MyAdapter(list, this);
myrecyclerview.setAdapter(myadapter);
myrecyclerview.setHasFixedSize(true);
mylayoutmanager = new LinearLayoutManager(getApplicationContext());
myrecyclerview.setLayoutManager(mylayoutmanager);
parseJsonData();
}
public void parseJsonData(){
JsonObjectRequest request = new JsonObjectRequest(
Request.Method.GET,
url, null,
new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
Toast.makeText(getApplicationContext(), response.toString(), Toast.LENGTH_SHORT).show();
try {
JSONArray jsonarray = response.getJSONArray("results");
for (int i = 0; i < jsonarray.length(); i++) {
JSONObject jsonobject = jsonarray.getJSONObject(i);
String name = jsonobject.getString("name");
String height = jsonobject.getString("height");
String mass = jsonobject.getString("mass");
String eyecolor = jsonobject.getString("eye_color");
String birthyear = jsonobject.getString("birth_year");
//list.add(new RecyclerItem("darth vader", "200", "128", "1950", "red"));
list.add(new RecyclerItem(name, "Height: " + height, "Mass: " + mass, "Birth Year: " + birthyear, eyecolor));
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
error.printStackTrace();
}
});
listqueue.add(request);
}
#Override
public void onCharacterClick(int position) {
String color = list.get(position).getEyecolor();
Toast.makeText(getApplicationContext(), color, Toast.LENGTH_SHORT).show();
}
} ```
Like I mentioned, once I reload the activity, it works correctly. But I want the recycler view to show when I navigate to the activity.

The problem is that the first time that the activity is create, list is empty and parseJsonData() is running on the background filling that list.
Once you reload the activiy, the list and adapter are filled therefore when you call
myadapter = new MyAdapter(list, this);
myrecyclerview.setAdapter(myadapter);
myrecyclerview.setHasFixedSize(true);
mylayoutmanager = new LinearLayoutManager(getApplicationContext());
myrecyclerview.setLayoutManager(mylayoutmanager);
the recycler view is show. Try to do this on your parseJsonData(); after the loop ends, then create the adapter and show the rv
for (int i = 0; i < jsonarray.length(); i++) {
JSONObject jsonobject = jsonarray.getJSONObject(i);
....
}
myadapter = new MyAdapter(list, this);
....
myrecyclerview.setLayoutManager(mylayoutmanager);

I hope it help for u
Creat a List
private List< TipsList > tipsLists = new ArrayList<>();
SET UP RECYCLERVIEW LIKE THIS
RecyclerView tipsRv = findViewById(R.id.tips_rv);
TipsAdapter adapter = new TipsAdapter(tipsLists, this);
tipsRv.setAdapter(adapter);
tipsRv.setHasFixedSize(true);
tipsRv.setLayoutManager(new LinearLayoutManager(this));
getDATA
public void getWallis() {
String myJSONStr = method.loadJSON();
try {
JSONObject ROOT_OBJ = new JSONObject(myJSONStr);
JSONArray MAIN_ARRAY = ROOT_OBJ.getJSONArray("ff_api");
JSONObject TIPS_OBJ = MAIN_ARRAY.getJSONObject(3);
JSONArray TIPS_ARRAY = TIPS_OBJ.getJSONArray("Tips");
for (int i = 0; i < TIPS_ARRAY.length(); i++) {
TipsList tipsList = new TipsList();
JSONObject jsonObject = TIPS_ARRAY.getJSONObject(i);
tipsList.setId(jsonObject.getInt("id"));
tipsList.setTipsTitle(jsonObject.getString("tipsTitle"));
tipsList.setTipsDec(jsonObject.getString("tipsDec"));
tipsLists.add(tipsList);
}
} catch (JSONException e) {
e.printStackTrace();
}
}

Need help to retrieve all the data to listview

I'm trying to make an android application that can read data from a database. but when I try to display some rows in the listview, only the bottom row of the code that I make is displayed.
this is my code for MainActivity
public class MainActivity extends AppCompatActivity {
ListView listView;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = findViewById(R.id.listView);
getJSON("http://192.168.137.234/librenms/getdata.php");
}
private void getJSON(final String urlWebService) {
class GetJSON extends AsyncTask<Void, Void, String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
try {
loadIntoListView(s);
} catch (JSONException e) {
e.printStackTrace();
}
}
#Override
protected String doInBackground(Void... voids) {
try {
URL url = new URL(urlWebService);
HttpURLConnection con = (HttpURLConnection) url.openConnection();
StringBuilder sb = new StringBuilder();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));
String json;
while ((json = bufferedReader.readLine()) !=null) {
sb.append(json).append("\n");
}
return sb.toString().trim();
} catch (Exception e) {
return null;
}
}
}
GetJSON getJSON = new GetJSON();
getJSON.execute();
}
private void loadIntoListView(String json) throws JSONException {
JSONArray jsonArray = new JSONArray(json);
String[] alerts = new String[jsonArray.length()];
this is the part to showing the atribute on listview
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject object = jsonArray.getJSONObject(i);
alerts[i] = object.getString("Rule ID");
alerts[i] = object.getString("Device ID");
alerts[i] = object.getString("Time logged");
}
ArrayAdapter<String> arrayAdapter = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, alerts);
listView.setAdapter(arrayAdapter);
}
}

Volley - get the data from onResponse

I have a problem using Volley, I cant get data out from OnResponse mehod.
I need to use the List outside , for Fragment operations, but i couldn`t get it out from there. Maybe im doing something wrong, but i was unable to find a solution on other sites.
Can anyone help me find a solution please?
Here is my code:
public class MainActivity extends AppCompatActivity
{
private static final String JSON_URL = "http://Something/v1/Api.php?apicall=gettopics";
ListView listView;
List<Topic> topicList;
List<Topic> topicList2;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.listViewTopics);
topicList = new ArrayList<>();
loadTopics();
if(topicList.isEmpty())
{
TextView t = findViewById(R.id.text);
t.setText("Empty");
}
}
class TopicAdapter extends ArrayAdapter<Topic>
{
List<Topic> topicList;
public List<Topic> getTopicList() {
return topicList;
}
public TopicAdapter(List<Topic> topicList)
{
super(MainActivity.this, R.layout.layout_topic_list, topicList);
this.topicList = topicList;
}
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
LayoutInflater inflater = getLayoutInflater();
View listViewItem = inflater.inflate(R.layout.layout_topic_list, null, true);
TextView textViewName = listViewItem.findViewById(R.id.textViewTitle);
final Topic topic = topicList.get(position);
textViewName.setText(topic.getTitle());
return listViewItem;
}
}
public void loadTopics() {
StringRequest stringRequest = new StringRequest(Request.Method.GET, JSON_URL,
new Response.Listener<String>() {
#Override
public void onResponse(String response) {
try {
JSONObject obj = new JSONObject(response);
JSONArray topicArray = obj.getJSONArray("topics");
for (int i = 0; i < topicArray.length(); i++) {
JSONObject topicObject = topicArray.getJSONObject(i);
Topic topic = new Topic(topicObject.getInt("id"),topicObject.getInt("ordering"),topicObject.getString("title"));
topicList.add(topic);
}
TopicAdapter adapter = new TopicAdapter(topicList);
listView.setAdapter(adapter);
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
//displaying the error in toast if occurrs
Toast.makeText(getApplicationContext(), error.getMessage(), Toast.LENGTH_SHORT).show();
}
});
RequestQueue requestQueue = Volley.newRequestQueue(this);
requestQueue.add(stringRequest);
}
}

Firstly in onCreate():
topicList = new ArrayList<>();
listView = (ListView) findViewById(R.id.listViewTopics);
adapter = new TopicAdapter(topicList); //note:define 'adapter' as a class field as 'listView'
listView.setAdapter(adapter);
Then in onResponse():
topicList.clear();
try{
JSONObject obj = new JSONObject(response);
JSONArray topicArray = obj.getJSONArray("topics");
for (int i = 0; i < topicArray.length(); i++) {
JSONObject topicObject = topicArray.getJSONObject(i);
Topic topic = new Topic(topicObject.getInt("id"),topicObject.getInt("ordering"),topicObject.getString("title"));
topicList.add(topic);
}
adapter.notifyDataSetChanged();
} catch (JSONException e) {
e.printStackTrace();
}

how to add data in list view from background class

I am getting this exception
android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
Below is the code:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main_page2);
lv = (ListView) findViewById(R.id.list_view);
btnNew = (Button)findViewById(R.id.btnAddNew);
btnNew.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent moveToNewUser = new Intent(getApplication(),ExecutiveInfo2.class);
moveToNewUser.putExtra("ClickType","1");
startActivity(moveToNewUser);
}
});
new Connection2().execute();
// Listview Data
}
private class Connection2 extends AsyncTask {
#Override
protected Object doInBackground(Object... arg0) {
test2();
return null;
}
#Override
protected void onPostExecute(Object s) {
super.onPostExecute(s);
}
}
public void test2() {
HttpURLConnection connection = null;
try {
sharedpreferences = getSharedPreferences("MyPrefs", this.MODE_PRIVATE);
String storedUUID = sharedpreferences.getString("UUID", "");
String url2= "http://crm.xqicai.com/sales/getExecutiveInfo?UUID="+storedUUID;
//String url = "http://crm.xqicai.com/sales/login";
URL postUrl = new URL(url2);
connection = (HttpURLConnection) postUrl.openConnection();
connection.setDoOutput(true);
connection.setDoInput(true);
connection.setRequestMethod("GET");
connection.setUseCaches(false);
connection.setInstanceFollowRedirects(true);
connection.setRequestProperty("Content-Type", "application/json");
connection.connect();
BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream(), "utf-8"));// 设置编�,�则中文乱�
while (true) {
String str = reader.readLine();
if (str == null) {
break;
}
System.out.println(str);
JSONObject mainObject = new JSONObject(str);
Status = mainObject.getString("status");
int j=0;
if(Status.equals("0"))
{
JSONObject uniObject = mainObject.getJSONObject("data");
JSONArray a = uniObject.getJSONArray("data");
for (int i = 0; i < a.length(); i++) {
JSONObject json_obj = a.getJSONObject(i);
String demo = json_obj.getString("realName");
fetchedNames[j]= demo;
j++;
}
// Adding items to listview
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, fetchedNames);
lv.setAdapter(adapter);
}
else
{
JSONObject mainObject2 = new JSONObject(str);
errorMsg = mainObject2.getString("msg");
runOnUiThread(new Runnable() {
#Override
public void run() {
Toast.makeText(getApplicationContext(), errorMsg, Toast.LENGTH_SHORT).show();
}
});
}
}
} catch (Exception e) {
e.printStackTrace();
} finally {
}
}
I'm only a beginner, so please forgive me for asking possibly a stupid question.

What line is giving the error? The problem is that you update a view created in the main thread, in your AsyncTask (a different thread). You should update this view in the onPostExecute of your AsyncTask (this is done in your main thread). I don't see immediately where you update the view.
EDIT:
Your problem should be solved if you put these two lines
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, fetchedNames);
lv.setAdapter(adapter);
below this line:
lv = (ListView) findViewById(R.id.list_view);
or in the:
protected void onPostExecute(Object s)

Test that:
ListView lv...
lv.post(new Runnable() {
#Override
public void run() {
//Update UI;
lv.setAdapter(...);
}
})

you can try use Handler with sendEmptyMessage() inside asynctask to pass by exception.
ex.
Handler mHandler = new Handler(Looper.getMainLooper()) {
#Override
public void handleMessage(Message inputMessage) {
// Adding items to listview
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, fetchedNames);
lv.setAdapter(adapter);
}
});
note for code bellow:
//call mHandler.sendEmpyMessage() in asynctask:
if(Status.equals("0"))
{
JSONObject uniObject = mainObject.getJSONObject("data");
JSONArray a = uniObject.getJSONArray("data");
for (int i = 0; i < a.length(); i++) {
JSONObject json_obj = a.getJSONObject(i);
String demo = json_obj.getString("realName");
fetchedNames[j]= demo;
j++;
}
// Adding items to listview
mHandler.sendEmpyMessage(0); //0 or any number is identify code from you want use to check with every action

Android - How to get specific data from URL/JSON?

So I have this code, which is a page with a ListView search field and a button to confirm the search, when the button is pressed the ListView is filled with movie names from the Rotten Tomatoes API, The problem is that someone helped me with this code, and I would love some help breaking it down and understanding it sentence after sentence, My main goal is to get is to get the "title", "synopsis" and "url image" of a movie that was clicked in the list, and pass it with an intent to my other activity but the whole JSON and get specific data stuff, got me very confused.
Link to Rotten Tomatoes API documentation, this is my code:
public class MovieAddFromWeb extends Activity implements View.OnClickListener,
OnItemClickListener {
private TextView searchBox;
private Button bGo, bCancelAddFromWeb;
private ListView moviesList;
public List<String> movieTitles;
static final int ACTIVITY_WEB_ADD = 3;
// the Rotten Tomatoes API key
private static final String API_KEY = "8q6wh77s65aw435cab9rbzsq";
// the number of movies to show in the list
private static final int MOVIE_PAGE_LIMIT = 8;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.movie_add_from_web);
InitializeVariables();
}
/*
* Initializing the variables and creating the bridge between the views from
* the xml file and this class
*/
private void InitializeVariables() {
searchBox = (EditText) findViewById(R.id.etSearchBox);
bGo = (Button) findViewById(R.id.bGo);
bCancelAddFromWeb = (Button) findViewById(R.id.bCancelAddFromWeb);
moviesList = (ListView) findViewById(R.id.list_movies);
bGo.setOnClickListener(this);
bCancelAddFromWeb.setOnClickListener(this);
moviesList.setOnItemClickListener(this);
}
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.bGo:
new RequestTask()
.execute("http://api.rottentomatoes.com/api/public/v1.0/movies.json?apikey="
+ API_KEY
+ "&q="
+ searchBox.getText()
+ "&page_limit=" + MOVIE_PAGE_LIMIT);
break;
case R.id.bCancelAddFromWeb:
finish();
break;
}
}
private void refreshMoviesList(List<String> movieTitles) {
moviesList.setAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, movieTitles
.toArray(new String[movieTitles.size()])));
}
private class RequestTask extends AsyncTask<String, String, String> {
// make a request to the specified url
#Override
protected String doInBackground(String... uri) {
HttpClient httpclient = new DefaultHttpClient();
HttpResponse response;
String responseString = null;
try {
// make a HTTP request
response = httpclient.execute(new HttpGet(uri[0]));
StatusLine statusLine = response.getStatusLine();
if (statusLine.getStatusCode() == HttpStatus.SC_OK) {
ByteArrayOutputStream out = new ByteArrayOutputStream();
response.getEntity().writeTo(out);
out.close();
responseString = out.toString();
} else {
// close connection
response.getEntity().getContent().close();
throw new IOException(statusLine.getReasonPhrase());
}
} catch (Exception e) {
Log.d("Test", "Couldn't make a successful request!");
}
return responseString;
}
#Override
protected void onPostExecute(String response) {
super.onPostExecute(response);
try {
// convert the String response to a JSON object
JSONObject jsonResponse = new JSONObject(response);
// fetch the array of movies in the response
JSONArray jArray = jsonResponse.getJSONArray("movies");
// add each movie's title to a list
movieTitles = new ArrayList<String>();
for (int i = 0; i < jArray.length(); i++) {
JSONObject movie = jArray.getJSONObject(i);
movieTitles.add(movie.getString("title"));
}
// refresh the ListView
refreshMoviesList(movieTitles);
} catch (JSONException e) {
Log.d("Test", "Couldn't successfully parse the JSON response!");
}
}
}
#Override
public void onItemClick(AdapterView<?> av, View view, int position, long id) {
Intent openMovieEditor = new Intent(this, MovieEditor.class);
openMovieEditor.putExtra("movieTitle", movieTitles.get(position));
openMovieEditor.putExtra("callingActivity", ACTIVITY_WEB_ADD);
startActivityForResult(openMovieEditor, ACTIVITY_WEB_ADD);
}
}

see the modified code below..
public class MovieAddFromWeb extends Activity implements View.OnClickListener, OnItemClickListener {
private TextView searchBox;
private Button bGo, bCancelAddFromWeb;
private ListView moviesList;
public List<String> movieTitles;
//added new variables
public List<String> movieSynopsis;
public List<String> movieImgUrl;
static final int ACTIVITY_WEB_ADD = 3;
// the Rotten Tomatoes API key
private static final String API_KEY = "8q6wh77s65aw435cab9rbzsq";
// the number of movies to show in the list
private static final int MOVIE_PAGE_LIMIT = 8;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.movie_add_from_web);
InitializeVariables();
}
/*
* Initializing the variables and creating the bridge between the views from
* the xml file and this class
*/
private void InitializeVariables() {
searchBox = (EditText) findViewById(R.id.etSearchBox);
bGo = (Button) findViewById(R.id.bGo);
bCancelAddFromWeb = (Button) findViewById(R.id.bCancelAddFromWeb);
moviesList = (ListView) findViewById(R.id.list_movies);
bGo.setOnClickListener(this);
bCancelAddFromWeb.setOnClickListener(this);
moviesList.setOnItemClickListener(this);
}
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.bGo:
new RequestTask()
.execute("http://api.rottentomatoes.com/api/public/v1.0/movies.json?apikey="
+ API_KEY
+ "&q="
+ searchBox.getText()
+ "&page_limit=" + MOVIE_PAGE_LIMIT);
break;
case R.id.bCancelAddFromWeb:
finish();
break;
}
}
private void refreshMoviesList(List<String> movieTitles) {
moviesList.setAdapter(new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, movieTitles
.toArray(new String[movieTitles.size()])));
}
private class RequestTask extends AsyncTask<String, String, String> {
// make a request to the specified url
#Override
protected String doInBackground(String... uri) {
HttpClient httpclient = new DefaultHttpClient();
HttpResponse response;
String responseString = null;
try {
// make a HTTP request
response = httpclient.execute(new HttpGet(uri[0]));
StatusLine statusLine = response.getStatusLine();
if (statusLine.getStatusCode() == HttpStatus.SC_OK) {
ByteArrayOutputStream out = new ByteArrayOutputStream();
response.getEntity().writeTo(out);
out.close();
responseString = out.toString();
} else {
// close connection
response.getEntity().getContent().close();
throw new IOException(statusLine.getReasonPhrase());
}
} catch (Exception e) {
Log.d("Test", "Couldn't make a successful request!");
}
return responseString;
}
#Override
protected void onPostExecute(String response) {
super.onPostExecute(response);
try {
// convert the String response to a JSON object
JSONObject jsonResponse = new JSONObject(response);
// fetch the array of movies in the response
JSONArray jArray = jsonResponse.getJSONArray("movies");
// add each movie's title to a list
movieTitles = new ArrayList<String>();
//newly added
movieSynopsis = new ArrayList<String>();
movieImgUrl= new ArrayList<String>();
for (int i = 0; i < jArray.length(); i++) {
JSONObject movie = jArray.getJSONObject(i);
movieTitles.add(movie.getString("title"));
movieSynopsis.add(movie.getString(#add the synopsis var name returned by the JSON));
movieImgUrl.add(movie.getString(#add the urlvar name returned by the JSON));
}
// refresh the ListView
refreshMoviesList(movieTitles);
} catch (JSONException e) {
Log.d("Test", "Couldn't successfully parse the JSON response!");
}
}
}
#Override
public void onItemClick(AdapterView<?> av, View view, int position, long id) {
Intent openMovieEditor = new Intent(this, MovieEditor.class);
openMovieEditor.putExtra("movieTitle", movieTitles.get(position));
//newly added
openMovieEditor.putExtra("movieSynopsis", movieSynopsis.get(position));
openMovieEditor.putExtra("movieImgUrl", movieImgUrl.get(position));
openMovieEditor.putExtra("callingActivity", ACTIVITY_WEB_ADD);
startActivityForResult(openMovieEditor, ACTIVITY_WEB_ADD);
}