Develop Reference

Android Fragment populating listview with JSON

I am trying to do a fragment where there is a listview inside and I am trying to populate the listview using JSON. I only have one error and i dont know where to put the single error i have.
The error is pointing at the getJSON(); just below the return rootview saying invalid method declaration
Here is my code where it extends a fragment and inside is a listview
public class News extends Fragment {
private ListView lv;
private String JSON_STRING;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View rootView = inflater.inflate(news, container, false);
lv = (ListView) rootView.findViewById(R.id.listView3);
return rootView;
}
getJSON();
private void showResult(){
JSONObject jsonObject = null;
ArrayList<HashMap<String,String>> list = new ArrayList<>();
try {
jsonObject = new JSONObject(JSON_STRING);
JSONArray result = jsonObject.getJSONArray(Config.TAG_JSON_ARRAY1);
for(int i = 0; i<result.length(); i++){
JSONObject jo = result.getJSONObject(i);
String NID = jo.getString(Config.TAG_NID);
String title = jo.getString(Config.TAG_title);
String content = jo.getString(Config.TAG_content);
String n_date = jo.getString(Config.TAG_n_date);
HashMap<String,String> match = new HashMap<>();
match.put(Config.TAG_NID, NID);
match.put(Config.TAG_title,title);
match.put(Config.TAG_content,content);
match.put(Config.TAG_n_date,n_date);
list.add(match);
}
} catch (JSONException e) {
e.printStackTrace();
}
ListAdapter adapter = new SimpleAdapter(
getActivity(), list, R.layout.newsadapterlayout,
new String[]{Config.TAG_title,Config.TAG_content, Config.TAG_n_date, Config.TAG_NID},
new int[]{ R.id.title, R.id.content, R.id.n_date});
lv.setAdapter(adapter);
}
private void getJSON(){
class GetJSON extends AsyncTask<Void,Void,String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
JSON_STRING = s;
showResult();
}
#Override
protected String doInBackground(Void... params) {
RequestHandler rh = new RequestHandler();
String s = rh.sendGetRequest(Config.URL_NEWS);
return s;
}
}
GetJSON gj = new GetJSON();
gj.execute();
}
Any help would be very much appreciated. Thanks guys

You can't declare a class inside of a method.
Separate private void getJSON() from the class GetJSON, simply move the code outside of the method, you can still do; GetJSON gj = new GetJSON();

how to send ArrayList(Bitmap) from asyncTask to Fragment and use it in Arrayadapter

I want to send a list of bitmap i retreived from mysql database using asyncTask to the fragment Fragment_ListView.class, in this fragment class i want to set the adapter of the listView with the bitmap token from asyncTask but i don't know how to do that.
Async Task
#Override
protected void onPostExecute(ArrayList<Bitmap> bitmapArrayList) {
super.onPostExecute(bitmapArrayList);
loading.dismiss();
// now after getting images from server , i want to send this bitmapArrayList
// to Fragment_ListView where i set the adapter of the
}
#Override
protected ArrayList<Bitmap> doInBackground(String... params) {
imageList = new ArrayList();
String add1 = "http://192.168.1.11/save/load_image_from_db.php?id=1";
String add2 = "http://192.168.1.11/save/load_image_from_db.php?id=2";
String add3 = "http://192.168.1.11/save/load_image_from_db.php?id=3";
URL url;
Bitmap image = null;
String[] adds = {add1, add2, add3};
for (int i = 0; i < adds.length; i++) {
try {
url = new URL(adds[i]);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
image = BitmapFactory.decodeStream(connection.getInputStream());
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
imageList.add(image);
image = null;
}
return imageList;
OnCreate of MainActivity
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listfrg = new Fragment_ListView();
getFragmentManager().beginTransaction().add(R.id.frml, listfrg).commit();
}
Fragment_ListView :
public class Fragment_ListView extends Fragment {
ListView mListView;
static ArrayList<Bitmap> bitmaps;
static MySimpleArrayAdapter adapter;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.frglist, container, false);
mListView = (ListView) view.findViewById(R.id.listView);
bitmaps = new ArrayList<>();
adapter = new MySimpleArrayAdapter(getActivity(), bitmaps);
mListView.setAdapter(adapter);
return view;
}

Something like this,
Create a new interface file
public interface BitMapArrayCallBack {
abstract void bitmapArray(ArrayList<Bitmap> bitmaps);
}
Then in AsyncTask ... i don't know your class name so i will assume the class ServerRequest
public class ServerRequest {
Context context;
public ServerRequest(Context context) {
this.context = context;
}
public void doAsyncTask(BitMapArrayCallBack bitmapCallback) {
new MyAsyncTask(bitmapCallback).execute();
}
public class MyAsyncTask extends AsyncTask<Void, Void, Void> {
private BitMapArrayCallBack bitmapCallback;
public MyAsyncTask(BitMapArrayCallBack bitmapCallback) {
this.bitmapCallback = bitmapCallback;
}
//call do in background etc..
#Override
protected void onPostExecute(ArrayList<Bitmap> bitmapArrayList) {
super.onPostExecute(bitmapArrayList);
loading.dismiss();
bitmapCallback.bitmapArray(bitmapArrayList);
// This will hold and return your arraylist
}
}
}
Now you must call your asynctask in fragment listview
public class Fragment_ListView extends Fragment {
ListView mListView;
static MySimpleArrayAdapter adapter;
private ServerRequest serverRequest;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.frglist, container, false);
mListView = (ListView) view.findViewById(R.id.listView);
serverRequest = new ServerRequest(getActivity);
serverRequest.doAsyncTask(new BitMapArrayCallBack {
#Override
void bitMapArray(ArrayList<Bitmap> bitmaps) {
// in here you have access to the bitmaps array
adapter = new MySimpleArrayAdapter(getActivity(), bitmaps);
mListView.setAdapter(adapter);
}
})
return view;
}

Updating/Creating Custom Listview on PostExecute inside a Fragment

So I have a Sections Pager Application in Android. On my fourth fragment, I run an asynctask that connects to a device via bluetooth and updates a custom list that I created (supposedly) However, the list either updates late or doesn't update at all. I'm not exactly sure what to do on the postexecute to allow update so I updated it outside of the asynctask.
Code is below:
public class FourthFragment extends Fragment {
private WeakReference<getBeacons> getBeaconTaskWeakRef;
ArrayList<ArtInfo> ArtList = new ArrayList<>();
;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
startNewBeaconsAsyncTask();
}
ArrayList<String> titles = new ArrayList<>();
ArrayList<String> artists = new ArrayList<>();
ArrayList<String> years = new ArrayList<>();
ArrayList<Integer> images = new ArrayList<>();
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
for (int i = 0; i < ArtList.size(); i++) {
titles.add(ArtList.get(i).getArtTitle());
artists.add(ArtList.get(i).getArtistName());
years.add(ArtList.get(i).getYear());
int resID = getResources().getIdentifier(ArtList.get(i).getImageFilename(), "drawable", "com.acuart.acumen.acuart");
images.add(resID);
}
View v = inflater.inflate(R.layout.frag_list, container, false);
ListView byTitleList = (ListView) v.findViewById(R.id.byTitleList);
byTitleList.setAdapter(new titleList(getActivity(), R.layout.custom_list, titles));
return v;
}
private void startNewBeaconsAsyncTask() {
getBeacons newbeacons = new getBeacons(this);
this.getBeaconTaskWeakRef = new WeakReference<getBeacons>(newbeacons);
newbeacons.execute();
}
class titleList extends ArrayAdapter<String> {
public titleList(Context context, int resource, ArrayList<String> objects) {
super(context, resource, objects);
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = ((Activity) getContext()).getLayoutInflater().inflate(R.layout.custom_list, null);
TextView title = (TextView) v.findViewById(R.id.row_title);
TextView artist = (TextView) v.findViewById(R.id.row_artist);
TextView year = (TextView) v.findViewById(R.id.row_year);
ImageView image = (ImageView) v.findViewById(R.id.row_image);
title.setText(titles.get(position));
artist.setText(artists.get(position));
year.setText(years.get(position));
image.setBackgroundResource(images.get(position));
return v;
}
}
private class getBeacons extends AsyncTask<Void, Void, Void> {
private WeakReference<FourthFragment> fragmentWeakReference;
private getBeacons(FourthFragment fragment) {
this.fragmentWeakReference = new WeakReference<FourthFragment>(fragment);
}
ProgressDialog dialog = new ProgressDialog(getActivity());
Context context = getApplicationContext();
int artCount = 0;
SQLHelper markerDBHelper = new SQLHelper(context);
#Override
protected void onPreExecute() {
dialog.setMessage("Loading, please wait...");
dialog.show();
}
#Override
protected Void doInBackground(Void... params) {
checkBluetooth();
}
#Override
protected void onPostExecute(Void v) {
dialog.dismiss();
}
} //processing bluetooth data and creating a query for database return.
}
Any help/comments/ideas are appreciated.

Code in onPostExecute() runs on the UI thread, so you should be able to update your list adapter there.
I'm a bit confused by your question, are you saying that it takes a long time for onPostExecute() to run? Did you have your code in there to update the list, and then moved it out because onPostExecute() took too long to be called?
Do you have a bunch of other async tasks running?
I didn't have time to test compile/test this, so there could very well be some syntax mistakes, but this is just to give you an idea
In titleList add a method to update the data backing the adapter list so:
public void updateAdapterData(ArrayList<String> newData) {
clear();
addAll(newData);
notifyDataSetChanged();
}
And the async task could do something like this
private titleList mTitleList; //Set this in your onCreateView
private class getBeacons extends AsyncTask<Void, Void, ArrayList<String>> {
#Override
protected void onPreExecute() {
dialog.setMessage("Loading, please wait...");
dialog.show();
}
#Override
protected ArrayList<Object> doInBackground(Void... params) {
//If checkbluetooth returns a list..
return checkBluetooth();
}
#Override
protected void onPostExecute(ArrayList<String> newList) {
mTitleList.updateAdapterData(newList)
dialog.dismiss();
}
}

At First set the ListView adapter as follows:
titleList adapter=new titleList(getActivity(), R.layout.custom_list, titles));
byTitleList.setAdapter(adapter);
After doing the background task if you get an List of "titles", then in "onPostExecute" method you can do the following:-
private class getBeacons extends AsyncTask<Void, Void, ArrayList<String> > {
ArrayList<String> titles = new ArrayList<String>();
private getBeacons() {
}
#Override
protected void onPreExecute() {
}
#Override
protected ArrayList<String> doInBackground(Void... params) {
//call a method for assigning values to titles
return titles;
}
#Override
protected void onPostExecute(ArrayList<String> titles) {
//Now assign this arraylist referrence to your actual titles arraylist
adapter.notifyDataSetChanged();
}
}

You just need to update the ArrayList in your titleList adapter and call notifyDataSetChanged() on the adapter. I suggest doing this with a setList() method in the titleList class. You also need to keep a reference of the adapter where it is accessible by your AsyncTask.

onclick listener on listview without normal id

I have this code for create a custom listadapter
this is a part of my code:
protected void onPostExecute(String success)
{
ListAdapter adapter = new SimpleAdapter (context, jsonList,
R.layout.items, new String[]{TAG_PELI, TAG_nombre2},
new int[]{R.id.nombrePeli, R.id.nombreTwo});
setListAdapter(adapter);
getListView();
}
in my xml witht custom listview is:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<ListView
android:id="#android:id/list"
android:layout_width="300dp"
android:layout_height="300dp"
android:layout_centerHorizontal="true" >
</ListView>
the problem is that at call "onclicklistener" the id is not defined because is declared with
android:id="#android:id/list", I have to choose this form because thrown an error. what have I to call "oncliclistener". thanks
EDIT =============================== (SOLVED)
with this code works for me! :) Thanks
public class MainActivity extends Activity {
private Context context;
private static String url ="http://comupunt.esy.es/cities.php";
private static final String TAG_PELI = "name";
private static final String TAG_nombre2 = "nametwo";
ListView list;
ArrayList<HashMap<String, String>> jsonList = new ArrayList<HashMap<String,String>>();
protected void onCreate (Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
list =(ListView) findViewById(R.id.list);
new GetJSONActivity(MainActivity.this).execute();
list.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
HashMap<String,String> map =
(HashMap<String,String>)list.getItemAtPosition(position);
String value = map.get(TAG_PELI);
String products = map.get(TAG_nombre2);
Toast toast1 =
Toast.makeText(getApplicationContext(),
value, Toast.LENGTH_SHORT);
toast1.show();
}
});
}
public boolean onCreateOptionsMenu(Menu menu)
{
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
private class GetJSONActivity extends AsyncTask<String, Void, String>
{
private Activity activity;
public GetJSONActivity(Activity activity)
{
this.activity = activity;
context = activity;
}
#Override
protected String doInBackground(final String... args) {
// TODO Auto-generated method stub
JSONParser jparser = new JSONParser();
try{
JSONArray json = jparser.GetJSONfromUrl(url);
for(int i =0;i <json.length();i++){
try {
JSONObject c = json.getJSONObject(i);
String vpeli = c.getString(TAG_PELI);
String vname2 = c.getString(TAG_nombre2);
HashMap <String, String> map = new HashMap<String,String>();
map.put(TAG_PELI, vpeli);
map.put(TAG_nombre2, vname2);
jsonList.add(map);
} catch (JSONException e) {
// TODO: handle exception
e.printStackTrace();
return "error creando variables";
}
}
; }catch (Exception e)
{
}
return "exito";
}
protected void onPostExecute(String success)
{
ListAdapter adapter = new SimpleAdapter (context, jsonList,
R.layout.items, new String[]{TAG_PELI, TAG_nombre2},
new int[]{R.id.nombrePeli, R.id.nombreTwo});
list.setAdapter(adapter);
}
}
}

assign an id to your ListView in your xml file :
<ListView
android:id="#+id/my_list_id"
android:layout_width="300dp"
android:layout_height="300dp"
android:layout_centerHorizontal="true" >
</ListView>
and in your java code :
public class MainActivity extends Activity {
ListView list;
private Context context;
private static String url ="http://comupunt.esy.es/cities.php";
private static final String TAG_PELI = "name";
private static final String TAG_nombre2 = "nametwo";
ListView listView;
ArrayList<HashMap<String, String>> jsonList = new ArrayList<HashMap<String,String>>();
protected void onCreate (Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = findViewById(R.id.my_list_view);
new GetJSONActivity(MainActivity.this).execute();
}
public boolean onCreateOptionsMenu(Menu menu)
{
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
private class GetJSONActivity extends AsyncTask<String, Void, String>
{
private Activity activity;
public GetJSONActivity(Activity activity)
{
this.activity = activity;
context = activity;
}
#Override
protected String doInBackground(final String... args) {
// TODO Auto-generated method stub
JSONParser jparser = new JSONParser();
try{
JSONArray json = jparser.GetJSONfromUrl(url);
for(int i =0;i <json.length();i++){
try {
JSONObject c = json.getJSONObject(i);
String vpeli = c.getString(TAG_PELI);
String vname2 = c.getString(TAG_nombre2);
HashMap <String, String> map = new HashMap<String,String>();
map.put(TAG_PELI, vpeli);
map.put(TAG_nombre2, vname2);
jsonList.add(map);
} catch (JSONException e) {
// TODO: handle exception
e.printStackTrace();
return "error creando variables";
}
}
; }catch (Exception e)
{
}
return "exito";
}
protected void onPostExecute(String success)
{
ListAdapter adapter = new SimpleAdapter (context, jsonList,
R.layout.items, new String[]{TAG_PELI, TAG_nombre2},
new int[]{R.id.nombrePeli, R.id.nombreTwo});
listView.setAdapter(adapter);
notifyDataSetChanged();
}
}
}
now your list has a valid id and you can use it like this : R.id.my_list_id

Use your own app-specific ID in your XML, references using the "add to" syntax of #+id:
android:id="#+id/list"
Then you can references it in code as R.id.list.
=== Edit
Ok, I see what you are doing now, though you're not actually hooking up a listener. You should be able to do this:
getListView().setOnClickListener(this);
Then your Activity just implements the onClick() method appropriately (though I'm not sure that's really what you're trying to do here.)

implement AsyncTask in Fragment android

I've an activity which output json data from as a list. But now I want to implement it in a fragment.
In this fragment I want to view it as gridview. And both files works fine. but when I tried to implement AsyncTask I gets several redflags as unreachable code. Can someone help me with this please?
Edited: New
public class SalesFragment extends Fragment {
GridView gridView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View gv = inflater.inflate(R.layout.hot_sales, null);
gridView = (GridView) gv.findViewById(R.id.grid_view);
bindGridview();
return gv;
}
public void bindGridview() {
new MyAsyncTask(getActivity(),gridView).execute("");
}
class MyAsyncTask extends AsyncTask<String, String, String> {
GridView mGridView;
Activity mContext;
Response response;
public MyAsyncTask(Activity context,GridView gview) {
this.mGridView=gview;
this.mContext=context;
}
protected String doInBackground(String... params) {
File file = new File( Environment.getExternalStorageDirectory().getAbsolutePath() + "/Android/data/sample.txt");
if(file.exists()) {
try{
Reader inputStreamReader = new InputStreamReader(new FileInputStream(file));
Gson gson = new Gson();
this.response = gson.fromJson(inputStreamReader, Response.class);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (#SuppressWarnings("hiding") IOException e){
e.printStackTrace();
}
}else{
System.out.println("Error");
}
return null;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
//List<HashMap<String,String>> aList = new ArrayList<HashMap<String,String>>();
for(Sales sales : this.response.sales){
HashMap<String, String> hm = new HashMap<String,String>();
if (sales.getCategories1().contains("12")){
//hm.put("sale_title", "" + sales.getShort_title());
for(Shop shop : this.response.shops){
String image_file = new String( Environment.getExternalStorageDirectory().getAbsolutePath()
+ "/images/" + shop.getImage());
if(shop.getId().equals(sales.getShop_id())){
hm.put("shop_image", image_file );
System.out.println(shop_image);
}
}
if(hm.size()>0){
gridView.setAdapter(new ImageAdapter(MainActivity.this,R.layout.grid_layout , imgArray, titleArray));
}
}
}
}
}
}
How to call images into gridview on above image? Please help.

There is easy step to crate asyntask within fragment
in your fragment place code on activityCreateview
new MyAsyncTask(getActivity(), mListView).execute("");
getActivity() is method to communicate with fragment and activity
in asynstak on post
context.mListView.setArrayAdapter(...........)
here is
public class SalesFragment extends Fragment {
GridView gridView;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View gv = inflater.inflate(R.layout.hot_sales, null);
gridView = (GridView) gv.findViewById(R.id.grid_view);
bindGridView()
return gv;
//return super.onCreateView(inflater, container, savedInstanceState);
}
public void bindGridview()
{
new MyAsyncTask(getActivity(), gridView).execute("");
}
class MyAsyncTask extends AsyncTask<String, String, String>
{
GridView mGridView;
Activity mContex;
public MyAsyncTask(Activity contex,GridView gview)
{
this.mGridView=gview;
this.mContex=contex;
}
protected String doInBackground(String... params)
{
//fetch data
}
#Override
protected void onPostExecute(String result) {
{
for(Sales sales : this.response.sales){
HashMap<String, String> hm = new HashMap<String,String>();
if (sales.getCategories1().contains("12")){
//hm.put("sale_title", "" + sales.getShort_title());
for(Shop shop : this.response.shops){
String image_file = new String( Environment.getExternalStorageDirectory().getAbsolutePath()
+ "/images/" + shop.getImage());
if(shop.getId().equals(sales.getShop_id())){
hm.put("shop_image", image_file );
System.out.println(shop_image);
}
}
}
}
if(hm.size()>0)
mcontext.mGridView.setAdapter(new ImageAdapter(mContext),hm);
}
before fetching data make it model like
public class ImageModel
{
String title;
String img;
}
ArrayList<ImageModel> arrayList=new ArrayList<ImageModel>();
fill array list with required data
then
mcontext.mGridView.setAdapter(new ImageAdapter(mContext),hm,arrayList);
//in image adapter
public class ImageAdapter extends ArrayAdapter<String> {
public ImageAdapter(Context context, HashMap<String, String> hm,ArrayList<ImageModel> images )
{
super(context, R.layout.activity_t);
}
//--code
}
use hash map in adapter and assign images with position
set data and fetch value from model