Develop Reference

Arraylist of strings into one comma separated string

Trying to convert a Arraylist of strings into one big comma separated string.
However when I use the
String joined = TextUtils.join(", ", participants);
Debugger shows me size of 4 for participants however the joined value as "" therefore empty
private ArrayList<String> participants;
Not sure what is going wrong?
UPDATE:
List<String> list = new ArrayList<>();
list.add("Philip");
list.add("Paul Smith");
list.add("Raja");
list.add("Ez");
String s = TextUtils.join(", ", list);
This works when I have a list that I manually populate however below is how the code is working right now.
In the onCreate()
callApi(type);
String s = TextUtils.join(", ", participants);
getSupportActionBar().setTitle(s);
In callAPI():
JSONArray participantsR = sub.getJSONArray("referralParticipants");
Log.e("Participants length ", String.valueOf(participantsR.length()));
for (int i = 0; i < participantsR.length(); i++)
{
JSONObject object = participantsR.getJSONObject(i);
String firstname = (String) object.get("fullName");
participants.add(firstname);
Log.e("Times", String.valueOf(i));
}

I'm trying to reproduce your error and am unable to. Here is my code:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_temp);
List<String> list = new ArrayList<>();
list.add("Philip Johnson");
list.add("Paul Smith");
list.add("Raja P");
list.add("Ezhu Malai");
String s = TextUtils.join(", ", list);
Log.d(LOGTAG, s);
}
My output is Philip Johnson, Paul Smith, Raja P, Ezhu Malai as expected.
Are you importing the correct TextUtils class?
android.text.TextUtils;
Given the new information, here is my approach:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_temp);
callApi(type, new OnResponseListener<List<String>>() {
#Override public void onResponse(List<String> list) {
getSupportActionBar().setTitle(TextUtils.join(", ", list));
}
});
}
I don't know what networking library you're using, but you may have to define OnResponseListener as an interface. It's very easy:
public interface OnResponseListener<T> {
public void onResponse(T response);
}
You will then need to modify your callApi function to take an instance of OnResponseListener> and call it's onResponse method after completing the call.
I would recommend looking into the Volley library, and reading the Android documentation about simple network calls.

I use StringUtils.join from Apache Common Utilities.
The code is super-simple just the way you wanted,
StringUtils.join(participants,", ");
Works flawlessly for me.
EDIT
As requested, here is the StringUtils.java file for those who just want to use this single utility class and not the entire library.

I don't know what TextUtils does. This will do it.
StringBuffer sb = new StringBuffer();
for (String x : participants) {
sb.append(x);
sb.append(", ");
}
return sb.toString();
Easy enough, just use that.

Try with kotlin
val commaSeperatedString = listOfStringColumn.joinToString { it ->
"\'${it.nameOfStringVariable}\'" }
// output: 'One', 'Two', 'Three', 'Four', 'Five'

Appwarp Android Programming get Property from Room List Activity

I'm new in Multiplayer programming. How to set String into hashmap value ? I want to call hashmap properties from RoomListActivity and set it's value on QuizMaintain activity and also I want to set hashmap value from QuizMaintain class to textview. Here's my sample code
RoomListActivity
public void onJoinNewRoomClicked(View view){
progressDialog = ProgressDialog.show(this,"","Please wait...");
progressDialog.setCancelable(true);
HashMap<String, Object> properties = new HashMap<String, Object>();
properties.put("timer", "");
properties.put("question", "");
properties.put("answer", "");
properties.put("foulanswer", "");
theClient.createRoom(""+System.currentTimeMillis(), "Yoshua", 2, properties);
}
Then I want to set it's value from QuizMaintain activity
public class QuizMaintain extends Activity implements RoomRequestListener, NotifyListener {
private WarpClient theClient;
private HashMap<String, Object> properties;
private TextView txttimer,txtquestion;
private String roomId = "";
private HashMap<String, User> userMap = new HashMap<String, User>();
String string="5x5#5x4#150:3#500:20#536+59";
String[] questions = string.split("#");
String question1 = questions[0];
String question2 = questions[1];
String question3 = questions[2];
String question4 = questions[3];
String question5 = questions[4];
#Override
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_quiz_maintain);
txttimer = (TextView)findViewById(R.id.timer);
txtquestion = (TextView)findViewById(R.id.questionview);
try{
theClient = WarpClient.getInstance();
}catch(Exception e){
e.printStackTrace();
}
theClient.getLiveRoomInfo("143680827");
Intent intent = getIntent();
roomId = intent.getStringExtra("roomId");
init(roomId);
//setquestionview();
}
private void init(String roomId){
if(theClient!=null){
theClient.addRoomRequestListener(this);
theClient.addNotificationListener(this);
theClient.joinRoom(roomId);
}
}
#Override
public void onGetLiveRoomInfoDone(LiveRoomInfoEvent event) {
properties = event.getProperties();
properties.put("question", question1);
}
I want to set hashmap value where is the key are "question". And the value that i want to set are from split string.When I ask their support team if I want to get room properties I should call getLiveRoomInfo method and pass roomID as argument. A bit confused here. Thanks.
But it seems my problem are not solved yet. After call method updateRoomProperties but I got another error here. It's say WarpClient.AddZoneRequestListener(this) return null pointer exception

When you are creating a room you are passing a hashmap. This hashmap is stored as a JSON document inside the room on server. AppWarp calls it Room Properties.
Now to retrieve these properties you have to call getLiveRoomInfo method. This will present you the room properties. Here you are adding/changing some key-value again. But you haven't told the server that you are updating these room properties. Therefore your changes remain local and that too limited to the scope of function.
So, when you call the getLiveRoomInfo method, you won't see the changes as you haven't updated them on server. To update on server, you need to call updateRoomProperties method. In this method you can add or change your hashmap.

NullPointerException when using Aysnctask in android

I am writing an android application, I use Aysnctask to get the current weather using openWeatherAPI. but it gives me a NullPointerException at this line :
results[0]=t;
this is the Aysnctask class I wrote:
private class GetWeather extends AsyncTask<String[], Void, String[]>{
#Override
protected String[] doInBackground(String... params) {
// TODO Auto-generated method stub
try {
params[0]=currentLatitude;
params[1]=currentLongitude;
String Url1="http://api.openweathermap.org/data/2.5/weather?lat="+currentLatitude+"&lon="+currentLongitude;
s1=getJson(Url1);
//Toast.makeText(getApplicationContext(), "the ss = "+s1, Toast.LENGTH_LONG).show();
Log.d("yes","yes");
if(s1!=null){
JSONObject jObj1 = new JSONObject(s1);
Log.d("jsonOOO","jsonOOO");
Tem= jObj1.getJSONObject("main").getDouble("temp");
Log.d("temmm","temmm="+String.valueOf(Tem));
pressure=jObj1.getJSONObject("main").getDouble("pressure");
humm=jObj1.getJSONObject("main").getDouble("humidity");
wind=jObj1.getJSONObject("wind").getDouble("speed");
desc=jObj1.getJSONObject("weather").getDouble("description");
double tem_c=Tem-273.15;
Log.d("tem11","tem11="+String.valueOf(tem_c));
String t=Double.toString(tem_c);
String t=String.valueOf(tem_c);
Log.d("tem22","tem22="+t);
results[0]=t;
Log.d("results[0]=","results[0]"+results[0]);
results[1]=String.valueOf(pressure);
results[2]=String.valueOf(humm);
results[3]=String.valueOf(wind);
results[4]=String.valueOf(desc);
}
} catch (Exception e) {
// TODO: handle exception
}
return results;
}//do in background
#Override
protected void onPostExecute(String[] results) {
temp.setText(results[0]+"°C");
hum.setText(results[1]+ "%");
press.setText(results[2]+ " hPa");
windSpeed.setText(results[3]+ " mps");
condDescr.setText(results[4]);
}
}
the value of temp,pressure, etc.. is not null. I tried to print them in logCat and they were printed.

The results array needs to be declared and initialized (probably as a local variable in the doInBackground(String) method):
String[] results = new String[5];

It seems like you did not initialize String[] results before you called it.
Hence causing the NullPointerException.

You have to initialize your String Array like this : String[] results = new String[5];

results must be null. Null-check and initialize as below:
Log.d("tem22","tem22="+t);
if (results == null ) { //null-check
results = new String[5]; //initialize
}
results[0]=t;
Log.d("results[0]=","results[0]"+results[0]);
results[1]=String.valueOf(pressure);
results[2]=String.valueOf(humm);
results[3]=String.valueOf(wind);
results[4]=String.valueOf(desc);
To avoid such exceptions, it is better to configure your IDE to warn you about potential null de-referencing
(e.g in Eclipse -> Preferences -> Java -> Compiler -> Errors -> Warnings ->Null analysis)

Parsing JSON then adding multiple strings to an ArrayList

Currently working on an app that takes results from a search, parses the JSON object returned, and then adds the resulting pieces into a few ArrayLists within a class created called VenueList.
Here is the method that receives the results from the service and parses the JSON:
private static List<String> getResultsFromJson(String json) {
ArrayList<String> resultList = new ArrayList<String>();
try {
JSONObject resultsWrapper = (JSONObject) new JSONTokener(json).nextValue();
JSONArray results = resultsWrapper.getJSONArray("results");
for (int i = 0; i < results.length(); i++) {
JSONObject result = results.getJSONObject(i);
resultList.add(result.getString("text"));
}
}
catch (JSONException e) {
Log.e(TAG, "Failed to parse JSON.", e);
}
return resultList;
}
What results of this becomes a List variable call mResults (to clarify: mResults = getResultsFromJson(restResult);. That is then used, among other places, in the following loop that puts the results into an ArrayAdapter that is used for displaying them in a ListFragment:
for (String result : mResults) {
VenueList.addVenue(result, "HELLO WORLD");
adapter.add(result);
}
I also add the result to a class called VenueList that manages the results and makes them accessible for multiple views. It essentially just holds multiple ArrayLists that hold different types of details for each venue returned in the search. The method I use to add a venue to VenueList is below (and you can see it used in the for loop above):
public static void addVenue(String name, String geo) {
venueNames.add(name);
venueGeos.add(geo);
}
I want the addVenue method to be able to take multiple arguments and update the VenueList class. Yet, when I call the addVenue method in the for loop, I can only pass it String result (from the parameters of the loop) and can't figure out how to pass it a second argument (which should also come from the JSON parsed by getResultsFromJson) so I've used "HELLO WORLD" as a placeholder for now.
I realize getResultsFromJson only has one list returned. I need to be able to take multiple elements from the JSON object that I parse, and then add them to VenueList in the right order.
So my questions are:
1) Given the getResultsFromJson method and the for loop, how can I use the addVenue() method as designed? How do I parse multiple elements from the JSON, and then add them to the VenueList at the same time? I plan on adding more arguments to it later on, but I assume if I can make it work with two, I can make it work with four or five.
2) If that's not possible, how should the getResultsFromJson, the for loop, and the addVenue method be redesigned to work properly together?
Please let me know if you need more detail or code - happy to provide. Thank you!
EDIT - Full VenueList class:
public class VenueList {
private static ArrayList<String> venueNames;
private static ArrayList<String> venueGeos;
public VenueList() {
venueNames = new ArrayList<String>();
venueGeos = new ArrayList<String>();
}
public static void addVenue(String name, String geo) {
venueNames.add(name);
venueGeos.add(geo);
}
public static String getVenueName(int position) {
return venueNames.get(position);
}
public static String getVenueGeo(int position) {
return venueGeos.get(position);
}
public static void clearList() {
venueNames.clear();
venueGeos.clear();
}
}
Clarification: I will have additional ArrayLists for each element of data that I want to store about a venue (phone number, address, etc etc)

1) I don't think methods getResultsFromJson(String json) and addVenue(String name, String geo) fit your needs.
2) I would consider rewriting method getResultsFromJson(String json) to something like this:
private static SortedMap<Integer, List<String>> getResultsFromJson(String json) {
Map<Integer, String> resultMap = new TreeMap<Integer, String>();
//...
return resultMap;
}
where the number of keys of your map should be equal to the number of objects you're extracting info, and each one of them will properly have their own list of items just in the right order you extract them.
With this approach you can certainly change your logic to something like this:
// grab your retuned map and get an entrySet, the just iterate trough it
SortedMap<Integer, String> result = returnedMap.entrySet();
for (Entry<Integer, String> result : entrySet) {
Integer key = result.getKey(); // use it if you need it
List<String> yourDesiredItems = result.getValue(); // explicitly shown to know how to get it
VenueList.addVenue(yourDesiredItems);
}
public static void addVenue(List<String> yourDesiredItems) {
// refactor here to iterate the items trough the list and save properly
//....
}
EDIT -- as you wish to avoid the go-between map i'm assuming you need nothing to return from the method
First i'm providing you with a solution to your requirements, then i'll provide you with some tips cause i see some things that could smplify your design.
To save VenueList things directly from getResultsFromJSON do something like this:
private static void getResultsFromJson(String json) {
try {
JSONObject resultsWrapper = (JSONObject) new JSONTokener(json).nextValue();
JSONArray results = resultsWrapper.getJSONArray("results");
for (int i = 0; i < results.length(); i++) {
JSONObject result = results.getJSONObject(i);
//FOR EXAMPLE HERE IS WHERE YOU NEED TO EXTRACT INFO
String name = result.getString("name");
String geo = result.getString("geo");
// and then...
VenueList.addVenue(name, geo, ..., etc);
}
} catch (JSONException e) {
Log.e(TAG, "Failed to parse JSON.", e);
}
}
This implies that your addVenue method should know receive all params needed; as you can see this is just a way (that you can consider a workaround to your needs), however as i don't know all requirements that lead you to code this model, i will point to a few things you might consider:
1. If there's a reason for VenueList class to use everything static, consider doing this:
static{
venueNames = new ArrayList<String>();
venueGeos = new ArrayList<String>();
//....
}
private VenueList(){
}
This way you won't need to get an instance every time and also will avoid null pointer exceptions when doing VenueList.addVenue(...) without previous instantiation.
2. Instead of having an ArrayList for every characteristic in VenueList class consider defining a model object for a Venue like this:
public class Venue{
String name;
String geo;
//... etc
public Venue(){
}
// ... getters & setters
}
then if you need that VenueList class you will just have a list o Venue objects (List<Venue>), this means that instead of calling the method addVenue, you will first create a brand new instance of Venue class and will call the setter method of each characteristic, as an example of the refactored for loop from the workaround i provided you you'd be using something like this:
List<Venue> myListOfVenues = new ArrayList<Venue>();
for (int i = 0; i < results.length(); i++) {
JSONObject result = results.getJSONObject(i);
// THIS WOULD REMAIN THE SAME TO EXTRACT INFO
String name = result.getString("name");
String geo = result.getString("geo");
// and then instead of calling VenueList.addVenue(name, geo, ..., etc)...
Venue v = new Venue();
v.setName(name);
v.setGeo(geo);
// ...etc
myListOfVenues.add(v);
}
// Once you're done, set that List to VenueList class
VenueList.setVenueList(myListOfVenues);
So VenueList class would now have a single property List<Venue> venueList; and would suffer minor tweeks on methods getVenueName, etc... and everything would be more readable... i hope this helps you to get another approach to solve your problem, if i still don't make my point let me know and i'll try to help you out...

Pulling data from a remote mySQL database, using AsyncTask; only displaying very last table row

As the title says really. I have two columns. I want to put them into textviews so I did it. However only the bottom two results, one from each column gets shown. Very odd. Here is my code: http://pastebin.com/qNgfHfT3
The parsing/onPostExecute is towards the bottom where the issue is.
One thing to note: The logs labeled "work" & "dontwork" show all my results, however the logs in the onPostExecute (Google & Google1) only show the last result so I presume the error is in the transfer from parsing to displaying.
Would really appreciate any help here. Thanks.

If you are receiving a JSON response I'd suggest you to parse it by using Gson. It's strongly recommendable as long as you can parse the whole thing in a pair of lines.
Note that creating a proper object it is as easy as doing the following:
YourObject object = gson.fromJson(responseReader, YourObject.class);
or even if you are retrieving a list of items:
Type listType = new TypeToken<List<YourObject>>() {}.getType();
List<YourObject> objects = gson.fromJson(responseReader, listType);
Here's an example that fits exactly your needs
After the process is done you'll have your object (or list of objects) available in an accesible variable.
EDIT:
First your Asynctask should have the following params:
public class HttpTask extends AsyncTask<Void, Void, ArrayList<Driver>> {
and your doInBackground method will need to pass that array to your onPostExecute:
#Override
protected ArrayList<Driver> doInBackground(Void... params) {
For the rest, I take it when the JSon parsing starts.
//PARSING JSON DATA
try {
JSONObject json_data;
Driver d;
jArray = new JSONArray(result);
int l = jArray.length();
if(l>0){
ArrayList<Driver> drivers = newArrayListList<Driver>();
for (int i = 0; i < l; i++) {
json_data = jArray.getJSONObject(i);
d = new Driver(json_data.optString("Driver_full_name"), json_data.optString("Drives_for"));
drivers.add(d);
Log.i("work", returnString);
Log.i("dontwork", somethingelse);
}
} catch (JSONException e1) {
Log.d("DB", "Error somewhere");
CurrentSeasonDrivers_DriverName.this.runOnUiThread(new Runnable() {
public void run() {
Toast.makeText(CurrentSeasonDrivers_DriversName, "Could not parse data so shut up", Toast.LENGTH_LONG).show();
}
});
}
return drivers;
}
protected void onPostExecute(ArrayList<Drivers>... drivers) {
Log.i("Google", returnString);
Log.i("Google1", somethingelse);
String firstDriverName = drivers.get(0).name;
String firstDriverDrivesFor = drivers.get(0).drivesfor;
String secondDriverName = drivers.get(1).name;
TextView drivername = (TextView) findViewById(R.id.DriverName);
drivername.setText(firstDriverName);
TextView drivesfor = (TextView) findViewById(R.id.DrivesFor);
drivesfor.setText(firstDriverDrivesFor);
}
With this and an object for your driver will complete the circle.
public class Driver{
public String name;
public String drivesfor;
public Driver(String _name, String _drivesfor){
name = _name;
drivesfor = _drivesfor;
}
}
I guess you can take over from here.
Let me know about your progress.