Develop Reference

Problem in parsing JSON data using volley library

This is a simple program to gain the JSON data from the internet. answerWithAsyncTask() is an interface that ensures that all the downloaded data will only be added to questionArrayList when the download is complete.
Error: java.lang.IndexOutOfBoundsException: Index: 1, Size: 0
private List<Question> questionList;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Few findViewbyId's here. Ignoring them
questionList = new QuestionBank().getQuestions(new answerWithAsyncTask() {
#Override
public void asyncMe(ArrayList<Question> questionArrayList) {
questionTextview.setText(questionArrayList.get(currentQuestionIndex).getQuestionId());
}
});
updateQuestion(); //This is the newly added line
}
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.prev_button:
updateQuestion();
break;
}
}
private void updateQuestion() {
String question = questionList.get(1).getQuestionId();
questionTextview.setText(question);
}
UPDATE This is my getQuestions method.
String url ="https://raw.githubusercontent.com/curiousily/simple-quiz/master/script/statements-data.json";
private ArrayList<Question> questionArrayList= new ArrayList<>();
public List<Question> getQuestions (final answerWithAsyncTask callback){
JsonArrayRequest jsonArrayRequest =new JsonArrayRequest(Request.Method.GET, url, (String) null,
new Response.Listener<JSONArray>() {
#Override
public void onResponse(JSONArray response) {
for(int i=0;i<response.length();i++){
Question question = new Question();
try {
question.setQuestionId(response.getJSONArray(i).getString(0));
question.setTorF(response.getJSONArray(i).getBoolean(1));
questionArrayList.add(question);
} catch (JSONException e) {
e.printStackTrace();
}
}
if(null != callback) callback.asyncMe(questionArrayList);
}
},
new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
}
});
AppController.getInstance().addToRequestQueue(jsonArrayRequest);
return questionArrayList;
}
and this my interface answerWithAsyncTask
public interface answerWithAsyncTask {
void asyncMe(ArrayList<Question> arrayList);
}

You are getting this error because
private List<Question> questionList;
is empty. In your first code, you are not getting any error because you are not calling updateQuestion() which will try to fetch data from an empty list. The error is in 2nd code because it's trying to access that empty list. Your
return questionArrayList;
is not returning data to questionList. Here, you are trying to do interface callback, to implement it properly, please look at this answer and change your code accordingly,
Java Interface Callback

Why recyclerview adapter is not setting data properly?

Few days ago, I asked this question for avoiding repetition of reycylerview items whose accepted answer helped me to avoid data repetition.
But now I am facing new problems like: not showing all items sometimes only one like this . The real problem is even after getting all items from server properly data is not shown in recyclerView properly .Data are skipped randomly. I don't understand where the problem is. I even tried to use for loop instead of foreach but result was not different. Can anyone please help to fix this? It has been pain in the neck from last one week.
Code:
private List<TimelineData> timelineDataList=new ArrayList<>() ;
public void onCreateView(){
recyclerview.setLayoutManager(new LinearLayoutManager(ctx));
//Setting Adapter
adapter=new CustomRecyclerViewAdapter(timelineDataList);
recyclerview.setAdapter(adapter);
}
#Override
public void onStart() {
super.onStart();
// Fetching data from server
socket.disconnect();
socket.connect();
//Getting Data from server
JSONObject obj=new JSONObject();
try {
obj.put("timeline_posts","all");
socket.emit("data",obj);
} catch (JSONException e) {
e.printStackTrace();
}
}
void addTimelineData(String type,String time,String img_link){
boolean isRepeated = false;
for(TimelineData data : timelineDataList){
if(data.getTime().equals(time)){
isRepeated = true;
}
}
if(!isRepeated){
timelineDataList.add(new TimelineData(type,time,img_link));
}
adapter.notifyDataSetChanged();
}
private Emitter.Listener handlePosts = new Emitter.Listener(){
#Override
public void call(final Object... args){
try {
JSONArray jsonArray=(JSONArray)args[0];
timelineDataList.clear(); //clear data before inserting new one
for(int i=0;i<jsonArray.length();i++){
try {
JSONObject ob=jsonArray.getJSONObject(i);
post_type=ob.getString("post_type");
post_time=ob.getString("time");
post_link=ob.getString("img_link");
addTimelineData(post_type,post_time,post_link);
} catch (JSONException e) {
e.printStackTrace();
}
}
} catch (Exception e) {
Log.e("error",e.toString());
}
}
};
Adapter Code:
#Override
public void onBindViewHolder( CustomRecyclerViewHolder holder, int position) {
//Fetching TimelineData
TimelineData timelineData=totalList.get(position);
///Here I'm getting and converting array of image links which are there in jsonObject to arraylist
//Getting Imglink
Gson gson=new Gson();
Type type = new TypeToken<ArrayList<String>>() {}.getType();
ArrayList<String> arrayList = gson.fromJson(timelineData.getImg_link(), type);
//Setting ViewPager
CustomPagerAdapter adp=new CustomPagerAdapter(arrayList);
pager.setAdapter(new PagerAdapter() {
#Override
public int getCount() {
return 0;
}
#Override
public boolean isViewFromObject(View view, Object object) {
return false;
}
});
holder.pager.setCurrentItem(position, false);
holder.pager.clearAnimation();
adp.notifyDataSetChanged();
holder.pager.setAdapter(adp);
holder.pager.setOffscreenPageLimit(1);
}

You are using notifyDataSetChnaged() very quickly, change notify method by this. So that you notify only selected item which you inserted.
Recommended method : You will put below code in your adapter and call this method from for loop where you were setting notifyDataSetChnaged here String s will be replaced by your model class. By this way you just notify only one element when inserting one element. This will also create some inserting animation automatically.
public void insertItemInList(String s) {
if (list == null) list = new ArrayList<>();
list.add(s);
notifyItemInserted(list.size() - 1);
}
Or
You can call notify outside for loop when your work is done like this.
for(int i=0;i<jsonArray.length();i++) {
try {
JSONObject ob=jsonArray.getJSONObject(i);
post_type=ob.getString("post_type");
post_time=ob.getString("time");
post_link=ob.getString("img_link");
addTimelineData(post_type,post_time,post_link);
} catch (JSONException e) {
e.printStackTrace();
}
}
adapter.notifyDataSetChanged();
Issue is that you are notifying adapter rapidly, it can also lead to UI inconsistency.
Let me know if this resolves your issue.

You are modifying the data list in the non-UI thread which could cause problems in the RecyclerView. Instead, you should collect all the data in tempTimelineDataList at once and update the adapted timelineDataList in the UI thread.

Sync Sqlite Database With Remote Server in Android

I store data with sqlite database from remote server with AsyncTask..
I have used Retrofit to fetch data, and now I want to store that data into sqlite... I already have DatabaseHelper.class , Model Class and NavigationDrawer in that i am performing AsynckTask in MainActivity.
private class getDataToSqlite extends AsyncTask<Post, Void, Void>{
#Override
protected Void doInBackground(Post... params) {
apiInterface.getContacts().enqueue(new Callback<List<Post>>() {
#Override
public void onResponse(Call<List<Post>> call, Response<List<Post>> response) {
if (response.isSuccessful()){
contacts = response.body();
for (int i=0; i < contacts.size(); i++){
Post post = contacts.get(i);
SaveToDatabase task = new SaveToDatabase();
task.execute(post);
adapter.addPost(post);
}
}else {
}
}
#Override
public void onFailure(Call<List<Post>> call, Throwable t) {
Toast.makeText(getApplicationContext(), "Error" + t.toString(), Toast.LENGTH_SHORT).show();
}
});
return null ;
}
}
private class SaveToDatabase extends AsyncTask<Post, Void , Void> {
#Override
protected Void doInBackground(Post... params) {
Post post = params[0];
try {
myDb.addData(post);
} catch (Exception e) {
Log.d(TAG, e.getMessage());
}
return null;
}
}
That class present in MainActivity
and i call the class in onCreate
new getDataToSqlite();
where i doing wrong please tell me

You can do something like this that I have already Done :
public boolean SyncCityMasterToDevice() {
try {
DatabaseHandler db = new DatabaseHandler(mContext);
db.dbDelete(TableCityMaster.TABLE);
List<CityMaster> cityMasterList = ServerRepo.getCities();
db.dbAddCity(cityMasterList);
Log.d(TAG, "SyncCityMasterToDevice: ");
return true;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
ServerRepo.getCities(); is a Retrofit Call.
I have called SyncCityMasterToDevice() method in an Async task
`DatabaseHandler` is the Database Helper Class.

Testing RX java

public void getTerms(boolean showDialog) {
service.getTermsFromServer().subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()).subscribe(new SingleSubscriber<String>() {
#Override
public void onSuccess(String value) {
try {
JSONObject jsonObject = new JSONObject(value);
JSONObject data = jsonObject.getJSONObject("data");
String content = data.getString("content");
String id = data.getString("id");
if (showDialog) {
***signUpView.showDialog(content, id)***;
} else {
agreeTerms(id);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
#Override
public void onError(Throwable error) {
Log.e(getClass().getName(), "Error : " + new Gson().toJson(error.getStackTrace()));
ErrorCheck.processError(error, gson, signUpView);
}
});
}
Please help me in testing this code. I have attached the method which i want to test. Here I want to verify that showDialog method gets called
Attaching the Unit test code also
#Test
public void testGetTermsCalled(){
String terms= "{\"data\":{\"id\":\"67f07c7a482542\",\"content\":\"<h3>Part of the test</h3>\",\"timestamp\":1484768675815,\"timestampFormatted\":\"2017-01-18T19:44:35\"},\"metadata\":null,\"version\":{\"id\":\"v1\",\"versionStatus\":\"candidate\",\"message\":null}}";
TestSubscriber<String> testSubscriber = new TestSubscriber<>();
signUpService.getTermsFromServer().just(terms).subscribe(testSubscriber);
signUpPresenter.getTerms(true);
Mockito.verify(signUpView).showDialog("<h3>Part of the test</h3>","67f07c71-1707-4b7a-a168-d7d05a482542");
}
Thanks!!!

Use RxJavaPlugins.setInitIoSchedulerHandler and RxAndroidPlugins.registerSchedulersHook to specify your own TestScheduler, then use its advanceTimeBy method to make some time pass, then verify that the expected calls happened.

Getting data from xml in android

I am working on android application. In my app I got the xml data response from server and stored it in a string. Now I need to get each value of that xml and display in a dropdown. How can I do that. Please help me with this. Will be really thankful.
My xml data:
<?xml version="1.0" encoding="utf-8"?>
<root>
<status>first<status>
<description>very good</description>
<Firstnames>
<name>CoderzHeaven</name>
<name>Android</name>
<name>iphone</name>
</Firstnames>
<SecondNames>
<name>Google</name>
<name>Android</name>
</SecondNames>
</root>
I am getting the above mentioned xml data from server. Now I need to display that in listview. How can I get those values using xmlparser. I tried with different examples but it didnt work for me.

You will need to create an extra class and parametrize your adapter with objects of this class, an example data model would look like:
public class DataClass {
private String status, description;
private ArrayList<String> fnames, lnames;
public DataClass() {
fnames = new ArrayList<String>();
lnames = new ArrayList<String>();
}
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public ArrayList<String> getFnames() {
return fnames;
}
public ArrayList<String> getLnames() {
return lnames;
}
}
As for the XML parser, there are literally tons of examples, you're definitely in advantage if you can use search. Just to give you a staring point, tutorials one, two, three, four.
If you experience problems, post your efforts and the code that didn't work, what have you tried and so on. Then you'll get help, otherwise nobody on SO is going to write code for you. https://stackoverflow.com/help/how-to-ask

Here's how you can do it if the xml is inside of your apps assets folder.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
InputStream input = null;
try {
input = getApplicationContext().getAssets().open("data.xml");
} catch (IOException e) {
e.printStackTrace();
}
DocumentBuilder builder = null;
try {
builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
} catch (ParserConfigurationException e) {
e.printStackTrace();
}
Document doc = null;
if (builder == null) {
Log.e("TAG", "Builder is empty.");
return;
}
try {
doc = builder.parse(input);
} catch (SAXException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
if (doc == null) {
Log.e("TAG", "Document is empty.");
return;
}
// Get Firstnames element
Element firstNames = (Element) doc.getElementsByTagName("Firstnames").item(0);
// Get name nodes from Firstnames
NodeList nameNodes = firstNames.getElementsByTagName("name");
// Get count of names inside of Firstnames
int cChildren = nameNodes.getLength();
List<String> names = new ArrayList<String>(cChildren);
for (int i=0; i<cChildren; i++) {
names.add(nameNodes.item(i).getTextContent());
Log.d("TAG","Name: "+names.get(i));
}
// Do same with SecondNames
}