Develop Reference

Invoke Virtual Method on null object reference

I am trying to implement fragments for a project in Android Studio. The point of the project is to select a color from a spinner in one fragment then pass it to the parent activity and then pass it from the parent activity to the second fragment to change the background color of the second fragment. The problem I am having is my listener in the palette activity is set to null despite the fact I invoke it in the onAttach function.
This is my code for the Fragment that causes the app to crash
package edu.temple.palettecolorapp;
import android.content.Context;
import android.graphics.Color;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.Spinner;
/**
* A simple {#link Fragment} subclass.
* Activities that contain this fragment must implement the
* {#link PaletteFragment.OnFragmentInteractionListener} interface
* to handle interaction events.
* Use the {#link PaletteFragment#newInstance} factory method to
* create an instance of this fragment.
*/
public class PaletteFragment extends Fragment {
private String colorArr[];
private String translationArr[];
Context parent;
private final String mParam1 = "colors";
private final String mParam2 = "translation";
public OnFragmentInteractionListener mListener;
public PaletteFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
*
* #return A new instance of fragment PaletteFragment.
*/
// TODO: Rename and change types and number of parameters
public static PaletteFragment newInstance(String colors[], String translation[]) {
PaletteFragment fragment = new PaletteFragment();
Bundle args = new Bundle();
args.putStringArray("colors", colors);
args.putStringArray("translation", translation);
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
this.colorArr = getArguments().getStringArray(mParam1);
this.translationArr = getArguments().getStringArray(mParam2);
}
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
this.parent = context;
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) parent;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
// this.parent = context;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_palette, container, false);
Spinner spinner = v.findViewById(R.id.spinner);
PaletteAdapter pa = new PaletteAdapter(parent,colorArr,translationArr);
spinner.setAdapter(pa);
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String c = colorArr[position];
mListener.onColorSelection(c);
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
return v;
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
public void onColorSelection(String color);
}
}
This is in the main activity
package edu.temple.palettecolorapp;
import android.content.Intent;
import android.content.res.Resources;
import android.net.Uri;
import android.support.constraint.ConstraintLayout;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.AdapterView;
import android.widget.Spinner;
import android.content.Context;
import android.graphics.Color;
import android.view.View;
public class PaletteActivity extends AppCompatActivity implements PaletteFragment.OnFragmentInteractionListener {
PaletteFragment master;
ColorFragment subject;
FragmentTransaction ft;
private final String colors[] = {"blue", "green", "purple", "red", "gray", "cyan", "magenta", "yellow", "lime"};
private boolean isSelected = false;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Context context = getApplicationContext();
Resources res = context.getResources();
String title = res.getString(R.string.palette_title);
setTitle(title);
setContentView(R.layout.activity_palette);
String translation[] = res.getStringArray(R.array.colors);
PaletteFragment master = PaletteFragment.newInstance(colors,translation);
ColorFragment subject = ColorFragment.newInstance("magenta");
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
ft.add(R.id.fragment1,master);
ft.replace(R.id.fragment2,subject);
ft.addToBackStack(null);
ft.commit();
}
#Override
public void onColorSelection(String color) {
subject.updateBackgroundColor(color);
}
}
I am having trouble in this portion of the fragment in the 'onCreateView' method
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_palette, container, false);
Spinner spinner = v.findViewById(R.id.spinner);
PaletteAdapter pa = new PaletteAdapter(parent,colorArr,translationArr);
spinner.setAdapter(pa);
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
String c = colorArr[position];
mListener.onColorSelection(c);
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
return v;
}
The 'mListener.onColorSelection' call causes the error and this is what the output is
E/AndroidRuntime: FATAL EXCEPTION: main
Process: edu.temple.palettecolorapp, PID: 14867
java.lang.NullPointerException: Attempt to invoke virtual method 'void edu.temple.palettecolorapp.ColorFragment.updateBackgroundColor(java.lang.String)' on a null object reference
at edu.temple.palettecolorapp.PaletteActivity.onColorSelection(PaletteActivity.java:45)
at edu.temple.palettecolorapp.PaletteFragment$1.onItemSelected(PaletteFragment.java:87)
at android.widget.AdapterView.fireOnSelected(AdapterView.java:944)
at android.widget.AdapterView.dispatchOnItemSelected(AdapterView.java:933)
at android.widget.AdapterView.access$300(AdapterView.java:53)
at android.widget.AdapterView$SelectionNotifier.run(AdapterView.java:898)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Edit2: added ColorFragment 'updateBackgroundColor' method
import android.content.Context;
import android.graphics.Color;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
/**
* A simple {#link Fragment} subclass.
* Activities that contain this fragment must implement the
* to handle interaction events.
* Use the {#link ColorFragment#newInstance} factory method to
* create an instance of this fragment.
*/
public class ColorFragment extends Fragment {
private View v;
TextView t;
String color;
private final String KEY = "color";
public ColorFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters
* #return A new instance of fragment ColorFragment.
*/
// TODO: Rename and change types and number of parameters
public static ColorFragment newInstance() {
ColorFragment fragment = new ColorFragment();
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
this.color = getArguments().getString(KEY);
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
v = inflater.inflate(R.layout.fragment_color, container, false);
t = v.findViewById(R.id.textView);
t.setBackgroundColor(Color.BLACK);
return v;
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
}
#Override
public void onDetach() {
super.onDetach();
}
public void updateBackgroundColor(String c){ // causing problems
t.setBackgroundColor(Color.parseColor(c));
}
}

Apparently ColorFragment subject in PaletteActivity is null when calling #onColorSelection().
Please check the assignment of value for the variable and make sure it is not null.
#Override
public void onColorSelection(String color) {
subject.updateBackgroundColor(color);
}
EDIT:
change the line:
ColorFragment subject = ColorFragment.newInstance("magenta");
TO:
subject = ColorFragment.newInstance("magenta");

Cannot transfer downloaded data from activity to fragment using bundle in android

I have been trying to pass some downloaded content from my activity to fragment in vain. I've broken up the steps to see where the error pops up and have made a few conclusions: (i) switching between fragment and activity and vice versa works fine.
(ii) Problem arises only when I enter some data and try to pass it to the fragment from the activity using a bundle.
Here is my fragment code:
package com.antojoh.bottomnavig;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.widget.CardView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
/**
* A simple {#link Fragment} subclass.
* Activities that contain this fragment must implement the
* {#link ShopFragment.OnFragmentInteractionListener} interface
* to handle interaction events.
* Use the {#link ShopFragment#newInstance} factory method to
* create an instance of this fragment.
*/
public class ShopFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
static ArrayList<String> arrayList = new ArrayList<String>();
static ArrayAdapter<String> arrayAdapter;
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
public ShopFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* #param param1 Parameter 1.
* #param param2 Parameter 2.
* #return A new instance of fragment ShopFragment.
*/
// TODO: Rename and change types and number of parameters
public static ShopFragment newInstance(String param1, String param2) {
ShopFragment fragment = new ShopFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_shop, container, false);
ListView listView = (ListView) view.findViewById(R.id.list);
arrayAdapter = new ArrayAdapter<String>(getContext(), android.R.layout.simple_list_item_checked, arrayList);
listView.setAdapter(arrayAdapter);
CardView cardView = (CardView) view.findViewById(R.id.cardView);
cardView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Intent intent = new Intent(getContext(), BarcodeActivity.class);
startActivity(intent);
}
});
Bundle bundle = this.getArguments();
if (bundle != null){
String value = bundle.getString("coder");
arrayList.add(value);
arrayAdapter.notifyDataSetChanged();
}
return view;
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
Toast.makeText(context, "Shop Fragment", Toast.LENGTH_SHORT).show();
}
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
}
Here is my Activity Code :
package com.antojoh.bottomnavig;
import android.Manifest;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.AsyncTask;
import android.os.Vibrator;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.util.SparseArray;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import com.google.android.gms.vision.CameraSource;
import com.google.android.gms.vision.Detector;
import com.google.android.gms.vision.barcode.Barcode;
import com.google.android.gms.vision.barcode.BarcodeDetector;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class BarcodeActivity extends AppCompatActivity {
SurfaceView cameraPreview;
private EditText editText;
BarcodeDetector barcodeDetector;
CameraSource cameraSource;
final int RequestCameraPermissionID = 1001;
#Override
public void onRequestPermissionsResult(int requestCode, #NonNull String[] permissions, #NonNull int[] grantResults) {
switch (requestCode) {
case RequestCameraPermissionID: {
if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
try {
if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
return;
}
cameraSource.start(cameraPreview.getHolder());
} catch (IOException e) {
e.printStackTrace();
}
}
}
break;
}
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_barcode);
editText = (EditText) findViewById(R.id.editText);
cameraPreview = (SurfaceView) findViewById(R.id.cameraPreview);
barcodeDetector = new BarcodeDetector.Builder(this)
.setBarcodeFormats(Barcode.UPC_A | Barcode.UPC_E | Barcode.EAN_8 | Barcode.EAN_13 | Barcode.CODE_128 | Barcode.CODE_39 | Barcode.CODE_93 | Barcode.ISBN | Barcode.ITF)
.build();
cameraSource = new CameraSource.Builder(this, barcodeDetector)
.setRequestedPreviewSize(640, 480)
.setAutoFocusEnabled(true)
.build();
cameraPreview.getHolder().addCallback(new SurfaceHolder.Callback() {
#Override
public void surfaceCreated(SurfaceHolder surfaceHolder) {
if (ActivityCompat.checkSelfPermission(getApplicationContext(), Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(BarcodeActivity.this, new String[]{Manifest.permission.CAMERA}, RequestCameraPermissionID);
return;
}
try {
cameraSource.start(cameraPreview.getHolder());
}catch (IOException e){
e.printStackTrace();
}
}
#Override
public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {
}
#Override
public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
cameraSource.stop();
}
});
barcodeDetector.setProcessor(new Detector.Processor<Barcode>() {
#Override
public void release() {
}
#Override
public void receiveDetections(Detector.Detections<Barcode> detections) {
final SparseArray<Barcode> qrcodes = detections.getDetectedItems();
if (qrcodes.size() != 0){
update(qrcodes.valueAt(0).rawValue);
}
}
});
}
public class DownloadTask extends AsyncTask<String, Void, String>{
#Override
protected String doInBackground(String... urls) {
String result="";
URL url;
HttpURLConnection urlConnection=null;
try {
url = new URL(urls[0]);
urlConnection = (HttpURLConnection)url.openConnection();
InputStream in = urlConnection.getInputStream();
InputStreamReader reader = new InputStreamReader(in);
int data = reader.read();
while (data != -1){
char current = (char) data;
result += current;
data = reader.read();
}
return result;
}catch (Exception e){
e.printStackTrace();
}
return null;
}
}
public void update(String string) {
String result = "";
DownloadTask task = new DownloadTask();
try {
result = task.execute("https://www.barcodable.com/ean/" + string).get();
} catch (Exception e) {
e.printStackTrace();
}
Pattern p = Pattern.compile("<title>UPC (.*?)</title>");
Matcher m = p.matcher(result);
while (m.find()) {
if (m.group(1) != null) {
Bundle bundle = new Bundle();
bundle.putString("coder", m.group(1));
ShopFragment shopFragment = new ShopFragment();
shopFragment.setArguments(bundle);
getSupportFragmentManager().beginTransaction().replace(R.id.cont, shopFragment).commit();
}
}
}
public void enter(View view){
update(editText.getText().toString());
}
}
And the Logcat :
08-14 14:46:03.037 5419-5460/com.antojoh.bottomnavig W/System.err: java.io.FileNotFoundException: https://www.barcodable.com/ean/9781614272137
at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:250)
at com.android.okhttp.internal.huc.DelegatingHttpsURLConnection.getInputStream(DelegatingHttpsURLConnection.java:210)
at com.android.okhttp.internal.huc.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java)
at com.antojoh.bottomnavig.BarcodeActivity$DownloadTask.doInBackground(BarcodeActivity.java:144)
at com.antojoh.bottomnavig.BarcodeActivity$DownloadTask.doInBackground(BarcodeActivity.java:134)
at android.os.AsyncTask$2.call(AsyncTask.java:304)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:243)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
08-14 14:46:03.038 5419-5460/com.antojoh.bottomnavig W/System.err: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
at java.lang.Thread.run(Thread.java:761)
08-14 14:46:03.041 5419-5419/com.antojoh.bottomnavig E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.antojoh.bottomnavig, PID: 5419
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:389)
at android.view.View.performClick(View.java:5610)
at android.view.View$PerformClick.run(View.java:22265)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:384)
at android.view.View.performClick(View.java:5610) 
at android.view.View$PerformClick.run(View.java:22265) 
at android.os.Handler.handleCallback(Handler.java:751) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6077) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756) 
Caused by: java.lang.NullPointerException: Attempt to invoke interface method 'int java.lang.CharSequence.length()' on a null object reference
at java.util.regex.Matcher.reset(Matcher.java:995)
at java.util.regex.Matcher.<init>(Matcher.java:174)
at java.util.regex.Pattern.matcher(Pattern.java:1006)
at com.antojoh.bottomnavig.BarcodeActivity.update(BarcodeActivity.java:171)
at com.antojoh.bottomnavig.BarcodeActivity.enter(BarcodeActivity.java:190)
at java.lang.reflect.Method.invoke(Native Method) 
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:384) 
at android.view.View.performClick(View.java:5610) 
at android.view.View$PerformClick.run(View.java:22265) 
at android.os.Handler.handleCallback(Handler.java:751) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6077) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756) 

It was simple. The website did not accept too many requests at a time( which I did). So all i had to do was either switch to another website or wait for a specific time to gain entry for requesting access again! Thanks!

Why doesn't this class return the JSON data from given URL?

The class that I have made does not fetch data from the given URL which I have as a String. In a static initializer I make a URL from the String, and then getResponseFromHttpUrl method should have returned the JSON data as a String. However my Log.d("jsondata") don't show anything at all and my app crashes.
package com.example.android.bakingapp;
import android.util.Log;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Scanner;
public class RecipeJson {
public static final String url = "https://d17h27t6h515a5.cloudfront.net/topher/2017/May/59121517_baking/baking.json";
public static URL urlBuilt;
public static String jsonData;
static {
try {
urlBuilt = buildUrl();
jsonData = getResponseFromHttpUrl(urlBuilt);
Log.d("jsondata", jsonData);
} catch (Exception e) {
e.printStackTrace();
}
}
public static URL buildUrl() throws java.net.MalformedURLException {
return new URL(url);
}
public static String getResponseFromHttpUrl(URL url) throws IOException {
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
try {
InputStream in = urlConnection.getInputStream();
Scanner scanner = new Scanner(in);
scanner.useDelimiter("\\A");
boolean hasInput = scanner.hasNext();
if (hasInput) {
return scanner.next();
} else {
return null;
}
} finally {
urlConnection.disconnect();
}
}
}
Here are the app logs:
08-07 20:59:54.776 26319-26319/com.example.android.bakingapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.android.bakingapp, PID: 26319
java.lang.ExceptionInInitializerError
at com.example.android.bakingapp.RecipeListFragment.onCreateView(RecipeListFragment.java:68)
at android.support.v4.app.Fragment.performCreateView(Fragment.java:2346)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1428)
at android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1759)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1827)
at android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:797)
at android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2596)
at android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2383)
at android.support.v4.app.FragmentManagerImpl.removeRedundantOperationsAndExecute(FragmentManager.java:2338)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:2245)
at android.support.v4.app.FragmentManagerImpl.dispatchStateChange(FragmentManager.java:3248)
at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:3200)
at android.support.v4.app.FragmentController.dispatchActivityCreated(FragmentController.java:195)
at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:597)
at android.support.v7.app.AppCompatActivity.onStart(AppCompatActivity.java:177)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1382)
at android.app.Activity.performStart(Activity.java:7151)
at android.app.ActivityThread.handleStartActivity(ActivityThread.java:2949)
at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:194)
at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:180)
at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:157)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:72)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1800)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6649)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:826)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
at org.json.JSONTokener.nextValue(JSONTokener.java:94)
at org.json.JSONArray.<init>(JSONArray.java:92)
at org.json.JSONArray.<init>(JSONArray.java:108)
at com.example.android.bakingapp.dummy.DummyContent.makeJsonArray(DummyContent.java:55)
at com.example.android.bakingapp.dummy.DummyContent.<clinit>(DummyContent.java:28)
The culprit is this line:
jsonArray = new JSONArray(RecipeJson.jsonData);
Which means the problem is really with my class. But what is the source of the problem?
Edit: Here is the RecipeListFragment code
package com.example.android.bakingapp;
import android.content.Context;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.example.android.bakingapp.dummy.DummyContent;
import com.example.android.bakingapp.dummy.DummyContent.DummyItem;
/**
* A fragment representing a list of Items.
* <p/>
* Activities containing this fragment MUST implement the {#link OnListFragmentInteractionListener}
* interface.
*/
public class RecipeListFragment extends Fragment {
private static final String ARG_COLUMN_COUNT = "column-count";
int dp;
private int mColumnCount = 1;
private OnListFragmentInteractionListener mListener;
/**
* Mandatory empty constructor for the fragment manager to instantiate the
* fragment (e.g. upon screen orientation changes).
*/
public RecipeListFragment() {
}
public static RecipeListFragment newInstance(int columnCount) {
RecipeListFragment fragment = new RecipeListFragment();
Bundle args = new Bundle();
args.putInt(ARG_COLUMN_COUNT, columnCount);
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Configuration config = getResources().getConfiguration();
dp = config.smallestScreenWidthDp;
if (dp < 600) mColumnCount = 1;
else mColumnCount = 3;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_recipelist_list, container, false);
// Set the adapter
if (view instanceof RecyclerView) {
Context context = view.getContext();
RecyclerView recyclerView = (RecyclerView) view;
if (mColumnCount <= 1) {
recyclerView.setLayoutManager(new LinearLayoutManager(context));
} else {
recyclerView.setLayoutManager(new GridLayoutManager(context, mColumnCount));
}
recyclerView.setAdapter(new MyRecipeListRecyclerViewAdapter(DummyContent.ITEMS, mListener));
}
return view;
}
#Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnListFragmentInteractionListener) {
mListener = (OnListFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnListFragmentInteractionListener");
}
}
#Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p/>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnListFragmentInteractionListener {
void onListFragmentInteraction(DummyItem item);
}
}

"Unfortunately, App has stopped" After clicking the Item in ListView to Fragment Activity

I'm a beginner for doing this application and I encounter this problem after I put Listview in Tab Activity. In Listview there are items are onclick to go for the new activity (That activity is fragment) for VR Panorama View I will display the codes and logcat.
ImageLoaderTask
package com.example.computer.vratdragfinal;
import android.content.res.AssetManager;
import android.graphics.Bitmap;
import android.os.AsyncTask;
import com.google.vr.sdk.widgets.pano.VrPanoramaView;
import java.lang.ref.WeakReference;
import android.graphics.BitmapFactory;
import android.util.Log;
import java.io.IOException;
import java.io.InputStream;
public class ImageLoaderTask extends AsyncTask<AssetManager, Void, Bitmap> {
private static final String TAG = "ImageLoaderTask";
private final String assetName;
private final WeakReference<VrPanoramaView> viewReference;
private final VrPanoramaView.Options viewOptions;
private static WeakReference<Bitmap> lastBitmap = new WeakReference<>(null);
private static String lastName;
#Override
protected Bitmap doInBackground(AssetManager... params) {
AssetManager assetManager = params[0];
if (assetName.equals(lastName) && lastBitmap.get() != null) {
return lastBitmap.get();
}
try(InputStream istr = assetManager.open(assetName)) {
Bitmap b = BitmapFactory.decodeStream(istr);
lastBitmap = new WeakReference<>(b);
lastName = assetName;
return b;
} catch (IOException e) {
Log.e(TAG, "Could not decode default bitmap: " + e);
return null;
}
}
#Override
protected void onPostExecute(Bitmap bitmap) {
final VrPanoramaView vw = viewReference.get();
if (vw != null && bitmap != null) {
vw.loadImageFromBitmap(bitmap, viewOptions);
}
}
public ImageLoaderTask(VrPanoramaView view, VrPanoramaView.Options viewOptions, String assetName) {
viewReference = new WeakReference<>(view);
this.viewOptions = viewOptions;
this.assetName = assetName;
}
}
MainActivity
package com.example.computer.vratdragfinal;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
assert tabLayout != null;
tabLayout.addTab(tabLayout.newTab().setText(R.string.welcome));
tabLayout.addTab(tabLayout.newTab().setText(R.string.venue));
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
final ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
final PagerAdapter adapter = new FragmentStatePagerAdapter(getSupportFragmentManager()) {
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return new WelcomeFragment();
case 1:
return new ttsd();
}
return null;
}
#Override
public int getCount() {
return 2;
}
};
assert viewPager != null;
viewPager.setAdapter(adapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
public void refreshNow() {
finish();
overridePendingTransition(0,0);
startActivity(getIntent());
overridePendingTransition(0,0);
}
}
toptourist1
package com.example.computer.vratdragfinal;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.google.vr.sdk.widgets.pano.VrPanoramaView;
public class toptourist1 extends Fragment {
private VrPanoramaView panoWidgetView;
private ImageLoaderTask backgroundImageLoaderTask;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.activity_toptourist1, container,false);
panoWidgetView = (VrPanoramaView) v.findViewById(R.id.pano_view);
return v;
}
#Override
public void onPause() {
panoWidgetView.pauseRendering();
super.onPause();
}
#Override
public void onResume() {
panoWidgetView.resumeRendering();
super.onResume();
}
#Override
public void onDestroy() {
panoWidgetView.shutdown();
super.onDestroy();
}
private synchronized void loadPanoImage() {
ImageLoaderTask task = backgroundImageLoaderTask;
if (task != null && !task.isCancelled()) {
task.cancel(true);
}
VrPanoramaView.Options viewOptions = new VrPanoramaView.Options();
viewOptions.inputType = VrPanoramaView.Options.TYPE_STEREO_OVER_UNDER;
String panoImageName = "sample_converted.jpg";
task = new ImageLoaderTask(panoWidgetView, viewOptions, panoImageName);
task.execute(getActivity().getAssets());
backgroundImageLoaderTask = task;
}
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
loadPanoImage();
}
}
ttsd
package com.example.computer.vratdragfinal;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.widget.SwipeRefreshLayout;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import android.content.Intent;
import android.widget.AdapterView;
public class ttsd extends Fragment {
public ttsd() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.ttsd, container, false);
// Inflate the layout for this fragment
String[] awayStrings = {
"Tubbataha Reef",
"San Agustin Church",
"Mayon Volcano",
"Malapascua Island",
"Puerto Galera",
"Puerto Princesa Undergound River",
"Donsol",
"Banaue Rice Terraces",
};
ListView lv = (ListView) view.findViewById(R.id.listView2);
ArrayAdapter<String> lva = new ArrayAdapter<String>(
getActivity(), android.R.layout.simple_list_item_1, awayStrings);
lv.setAdapter(lva);
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
if(position==0) {
Intent myintent = new Intent(view.getContext(), toptourist1.class);
startActivityForResult(myintent, 0);
}
}
});
final SwipeRefreshLayout mSwipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.fragment_away);
mSwipeRefreshLayout.setOnRefreshListener(
new SwipeRefreshLayout.OnRefreshListener() {
#Override
public void onRefresh() {
((MainActivity) getActivity()).refreshNow();
Toast.makeText(getContext(), "Refresh Layout working", Toast.LENGTH_LONG).show();
}
}
);
return view;
}
}
ViewPageAdapter
package com.example.computer.vratdragfinal;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import java.util.ArrayList;
public class ViewPageAdapter extends FragmentPagerAdapter{
ArrayList<Fragment> fragments = new ArrayList<>();
ArrayList<String> tabTitles = new ArrayList<>();
public void addFragments (Fragment fragments,String tabTitles){
this.fragments.add(fragments);
this.tabTitles.add(tabTitles);
}
public ViewPageAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return fragments.get(position);
}
#Override
public int getCount() {
return fragments.size();
}
#Override
public CharSequence getPageTitle(int position) {
return tabTitles.get(position);
}
}
**WelcomeFragment**
package com.example.computer.vratdragfinal;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.google.vr.sdk.widgets.pano.VrPanoramaView;
public class WelcomeFragment extends Fragment {
private VrPanoramaView panoWidgetView;
private ImageLoaderTask backgroundImageLoaderTask;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.welcome_fragment, container,false);
panoWidgetView = (VrPanoramaView) v.findViewById(R.id.pano_view);
return v;
}
#Override
public void onPause() {
panoWidgetView.pauseRendering();
super.onPause();
}
#Override
public void onResume() {
panoWidgetView.resumeRendering();
super.onResume();
}
#Override
public void onDestroy() {
panoWidgetView.shutdown();
super.onDestroy();
}
private synchronized void loadPanoImage() {
ImageLoaderTask task = backgroundImageLoaderTask;
if (task != null && !task.isCancelled()) {
task.cancel(true);
}
VrPanoramaView.Options viewOptions = new VrPanoramaView.Options();
viewOptions.inputType = VrPanoramaView.Options.TYPE_STEREO_OVER_UNDER;
String panoImageName = "converted.jpg";
task = new ImageLoaderTask(panoWidgetView, viewOptions, panoImageName);
task.execute(getActivity().getAssets());
backgroundImageLoaderTask = task;
}
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
loadPanoImage();
}
}
Run
02/13 16:35:13: Launching app
$ adb shell am start -n "com.example.computer.vratdragfinal/com.example.computer.vratdragfinal.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER
Client not ready yet..Waiting for process to come online
Connected to process 7627 on device emulator-5554
Capturing and displaying logcat messages from application. This behavior can be disabled in the "Logcat output" section of the "Debugger" settings page.
W/art: Before Android 4.1, method int android.support.v7.widget.ListViewCompat.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView
D/EGL_emulation: eglMakeCurrent: 0xae834b80: ver 2 0
E/eglCodecCommon: glUtilsParamSize: unknow param 0x00008cdf
W/SdkConfigurationReader: VrParamsProvider returned null params, using defaults.
D/ConfigUtils: Parameters file not found for reading: java.io.FileNotFoundException: /storage/sdcard/Cardboard/current_device_params: open failed: ENOENT (No such file or directory)
I/GVR: [vr/gvr/capi/src/gvr.cc:94] Initialized GVR version 1.10.0
E/eglCodecCommon: glUtilsParamSize: unknow param 0x00008cdf
W/art: Attempt to remove local handle scope entry from IRT, ignoring
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.computer.vratdragfinal, PID: 7627
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.computer.vratdragfinal/com.example.computer.vratdragfinal.toptourist1}: java.lang.ClassCastException: com.example.computer.vratdragfinal.toptourist1 cannot be cast to android.app.Activity
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2236)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
at android.app.ActivityThread.access$800(ActivityThread.java:151)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
Caused by: java.lang.ClassCastException: com.example.computer.vratdragfinal.toptourist1 cannot be cast to android.app.Activity
at android.app.Instrumentation.newActivity(Instrumentation.java:1066)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2226)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
at android.app.ActivityThread.access$800(ActivityThread.java:151) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5254) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 
Application terminated.

You can't simply say here Activity is a fragment and can not redirect from one fragment to another using Intent. Intent is used to switch between activities. That's the reason behind the crash. Either use the mechanism by which you can redirect to fragment or if you want to use intent, you need to use activity instead of fragment.

Grid-view is not formed in horizontal-scrolling-pages like home screen when app is in Background or Process is died

I am developing Horizontal Scrolling pages and tabs
MY app is working well in all devices in foreground, but when it goes to background, after one hour, the logs saying that Process com.example.myapp has died. When i reopen the app , the gridview data is not appearing but when scrolling horizontally , getView() method displaying all data like images and text.
that means app has data but view is not formed when process has died. And if i press back button and re-open the app, It is working good
My MainActivity.java is here
package com.bbgusa.bbgdemo.ui.phone;
import java.util.List;
import java.util.Vector;
import org.json.JSONObject;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.widget.TabHost;
import com.bbgusa.bbgdemo.R;
import com.bbgusa.bbgdemo.listener.phone.CustomViewPager;
import com.bbgusa.bbgdemo.ui.chat.phone.ChatFragmentTab;
import com.bbgusa.bbgdemo.ui.dialpad.phone.DialerFragment;
import com.bbgusa.bbgdemo.ui.home.phone.AlarmFragmentPhone;
import com.bbgusa.bbgdemo.ui.home.phone.HomeFragment;
import com.bbgusa.bbgdemo.ui.home.phone.HomeFragmentTab;
import com.bbgusa.bbgdemo.ui.home.phone.InfoFragPhone;
import com.bbgusa.bbgdemo.ui.home.phone.MapPhone;
import com.bbgusa.bbgdemo.ui.home.phone.WeatherFragmentPhone;
import com.bbgusa.bbgdemo.ui.messages.phone.MessagesFragment;
import com.bbgusa.bbgdemo.ui.settings.phone.AboutFragment;
import com.bbgusa.bbgdemo.ui.tablet.ConstantsManager;
import com.bbgusa.bbgdemo.ui.tablet.OnFragmentChangedListenerPhone;
import com.bbgusa.bbgdemo.utils.common.UConnectUtils;
public class MainActivity extends FragmentActivity implements TabHost.OnTabChangeListener, ViewPager.OnPageChangeListener, OnFragmentChangedListenerPhone {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_phone);
this.initialiseTabHost(savedInstanceState);
initialiseViewPager();
}
/**
* Initialise ViewPager
*/
private void initialiseViewPager() {
List<Fragment> fragments = new Vector<Fragment>();
fragments.add(Fragment.instantiate(this,HomeFragmentTab.class.getName()));
fragments.add(Fragment.instantiate(this, DialerFragment.class.getName()));
fragments.add(Fragment.instantiate(this,MessagesFragment.class.getName()));
fragments.add(Fragment.instantiate(this,ChatFragmentTab.class.getName()));
fragments.add(Fragment.instantiate(this, AboutFragment.class.getName()));
this.mPagerAdapter = new PagerAdapter(super.getSupportFragmentManager(), fragments);
this.mViewPager = (CustomViewPager) findViewById(R.id.tabviewpager);
this.mViewPager.setAdapter(this.mPagerAdapter);
this.mViewPager.setOnPageChangeListener(this);
this.mViewPager.setOffscreenPageLimit(5);
this.mViewPager.setCurrentItem(0);
}
#Override
public void onFragmentChangePhone(JSONObject response, String whichView, String title, String mPhoneNo) {
Bundle b = new Bundle();
if(response != null)
b.putString("JSONObject", response.toString());
if(title != null)
b.putString("Title", title);
String propertyId = UConnectUtils.getPropertyId(mPref, getString(R.string.property_id));
b.putString(UConnectUtils.PROPERTY_ID_KEY, propertyId);
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction ft = fragmentManager.beginTransaction();
Fragment fragment = null;
if (whichView.equals(ConstantsManager.GRIDVIEWPAGER)) {
// getSupportFragmentManager().popBackStack();
fragment = new HomeFragment();
} else if (whichView.equals(ConstantsManager.WEATHER)) {
fragment = new WeatherFragmentPhone();
}else if (whichView.equals(ConstantsManager.ALARM)) {
fragment = new AlarmFragmentPhone();
}else if (whichView.equals(ConstantsManager.MAPS)) {
fragment = new MapPhone();
}else if (whichView.equals(ConstantsManager.HELP)) {
fragment = new InfoFragPhone();
}
if (whichView.equals(ConstantsManager.MAPS)) { // to show plus-icon on map top right corner
HomeFragment.getInstance().onGridViewVisibilityChanged(true);
HomeFragmentTab.getInstance().onFragmentTabChange(View.VISIBLE , title, "", View.VISIBLE);
} else if (!whichView.equals(ConstantsManager.GRIDVIEWPAGER)) {
HomeFragment.getInstance().onGridViewVisibilityChanged(true);
HomeFragmentTab.getInstance().onFragmentTabChange(View.VISIBLE , title, mPhoneNo, View.GONE);
}
fragment.setArguments(b);
ft.add(R.id.main_home_frag, fragment);
if (whichView.equals(ConstantsManager.GRIDVIEWPAGER)) {
fragmentManager.popBackStack();
} else {
ft.addToBackStack(fragment.toString());
}
ft.commit();
}
#Override
public void onPageScrollStateChanged(int arg0) {
// TODO Auto-generated method stub
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
// TODO Auto-generated method stub
}
#Override
public void onPageSelected(int arg0) {
// TODO Auto-generated method stub
}
#Override
public void onTabChanged(String tabId) {
// TODO Auto-generated method stub
}
}
and my HomeFragmentTab.java is
package com.bbgusa.bbgdemo.ui.home.phone;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.bbgusa.bbgdemo.R;
import com.bbgusa.bbgdemo.ui.phone.MainActivity;
import com.bbgusa.bbgdemo.ui.tablet.ConstantsManager;
import com.bbgusa.bbgdemo.ui.tablet.OnFragmentTabChangedListener;
#SuppressLint("NewApi")
public class HomeFragmentTab extends Fragment implements OnFragmentTabChangedListener{
private static final String TAG = HomeFragmentTab.class.getSimpleName();
private static HomeFragmentTab tab;
private MainActivity activityPhone;
public static HomeFragmentTab getInstance() {
return tab;
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
activityPhone = (MainActivity) activity;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v;
if (container == null) {
return null;
}
Log.i(TAG, "onCreateView");
v = inflater.inflate(R.layout.hometab_phone, container, false);
tab = this;
activityPhone.onFragmentChangePhone(null, ConstantsManager.GRIDVIEWPAGER, getResources().getString(R.string.app_name), "");
return v;
}
#Override
public void onFragmentTabChange(int i, String title, String mPhoneNo, int mapV) {
}
}
and HomeFragment.java is
package com.bbgusa.bbgdemo.ui.home.phone;
import java.util.Locale;
import org.json.JSONArray;
import org.json.JSONObject;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.content.SharedPreferences;
import android.content.res.Resources;
import android.graphics.drawable.ColorDrawable;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.view.Window;
import android.view.WindowManager;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
import android.widget.LinearLayout;
import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.bbgusa.bbgdemo.R;
import com.bbgusa.bbgdemo.ui.ImageCacheManager;
import com.bbgusa.bbgdemo.ui.cms.tablet.TestTopics;
import com.bbgusa.bbgdemo.ui.cms.tablet.TopicList;
import com.bbgusa.bbgdemo.ui.phone.MainActivity;
import com.bbgusa.bbgdemo.ui.tablet.onGridViewVisibilityChangedListener;
import com.bbgusa.bbgdemo.utils.common.UCConstants;
import com.bbgusa.bbgdemo.utils.common.UConnectUtils;
import com.viewpagerindicator.IconPageIndicator;
import com.viewpagerindicator.IconPagerAdapter;
import com.viewpagerindicator.PageIndicator;
public class HomeFragment extends Fragment implements onGridViewVisibilityChangedListener{
private static final String TAG = HomeFragment.class.getSimpleName();
private ViewPager mViewPager;
private MainActivity activity;
private PageIndicator mIndicator;
private Animation mRotateAnim;
private Dialog indiacatorDialog;
private LinearLayout homeFragmentLL;
private static HomeFragment homeFragment;
public static final HomeFragment getInstance() {
return homeFragment;
}
#Override
public void onAttach(Activity activity) {
super.onAttach(activity);
this.activity = (MainActivity) activity;
}
#Override
public void onCreate(Bundle savedInstanceState) {
Log.i(TAG, "onCreate");
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
if (container == null) {
return null;
}
View v = inflater.inflate(R.layout.home_phone, container, false);
homeFragment = this;
UConnectUtils.setLauncher(true);
mViewPager = (ViewPager) v.findViewById(R.id.viewpager);
mIndicator = (IconPageIndicator) v.findViewById(R.id.indicator);
homeFragmentLL = (LinearLayout) v.findViewById(R.id.homeFragment);
indiacatorDialog = new Dialog(getActivity());
indiacatorDialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
indiacatorDialog.getWindow().clearFlags(WindowManager.LayoutParams.FLAG_DIM_BEHIND);
indiacatorDialog.setContentView(R.layout.indicator_dialog);
indiacatorDialog.setCanceledOnTouchOutside(false);
Window window = indiacatorDialog.getWindow();
window.setBackgroundDrawable(new ColorDrawable(android.graphics.Color.TRANSPARENT));
mRotateAnim = AnimationUtils.loadAnimation(getActivity(), R.anim.rotate_and_scale);
UConnectUtils.addAnimationFrameCount(mRotateAnim);
indicatorAnim();
// for property id
// if (activity.isInterNetAvailable()) {
Log.i(TAG, "onCreateView========== isInterNetAvailable");
new CmsPropertyAsync(activity).execute(UCConstants.CMS_CONFIG_URL, UCConstants.CMS_CONFIG_KEY);
// }
return v;
}
protected void parseJson(JSONObject rootResponce) {
TestTopics.imageUrls.clear();
TestTopics.titles.clear();
TestTopics.mMainMenuID.clear();
TestTopics.mViewType.clear();
TestTopics.mPhoneNo.clear();
try {
//get the Version
String version = rootResponce.optString("VERSION");
SharedPreferences mPref;
SharedPreferences.Editor edit;
mPref = PreferenceManager.getDefaultSharedPreferences(getActivity().getApplicationContext());
edit = mPref.edit();
edit.putString(getResources().getString(R.string.pref_cms_version_key), version).commit();
JSONArray jsonArray = rootResponce.getJSONArray("MAINMENU");
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject childMenuObject = jsonArray.getJSONObject(i);
int mainMenuID = childMenuObject.optInt("mainMenuId");
String title = childMenuObject.optString("title");
String viewType = childMenuObject.optString("viewType");
String imageUrl = childMenuObject.optString("imageUrl");
String phoneNo = childMenuObject.optString("phoneNo");
TestTopics.mMainMenuID.add(mainMenuID);
TestTopics.imageUrls.add(imageUrl);
TestTopics.titles.add(title);
TestTopics.mViewType.add(viewType);
TestTopics.mPhoneNo.add(phoneNo);
}
// Create a TopicList for this demo. Save it as the shared instance
// in
// TopicList
String sampleText = getResources().getString(R.string.sample_topic_text);
TopicList tlist = new TopicList(sampleText);
TopicList.setInstance(tlist);
// Create an adapter object that creates the fragments that we need
// to display the images and titles of all the topics.
MyAdapter mAdapter = new MyAdapter(getActivity().getSupportFragmentManager(), tlist, getResources());
// mViewPager.removeAllViews();
mViewPager.setAdapter(mAdapter);
// mViewPager.setPageTransformer(true, new DepthPageTransformer());
mIndicator.setViewPager(mViewPager);
mIndicator.setCurrentItem(0);
mIndicator.notifyDataSetChanged();
ViewTreeObserver observer = mViewPager.getViewTreeObserver();
observer.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#SuppressLint("NewApi")
#SuppressWarnings("deprecation")
#Override
public void onGlobalLayout() {
mViewPager.bringChildToFront(mViewPager.getChildAt(0));
if(Build.VERSION.SDK_INT >= UCConstants.ICE_CREAM_SANDWICH_MR1){
mViewPager.getViewTreeObserver().removeOnGlobalLayoutListener(this);
}else{
mViewPager.getViewTreeObserver().removeGlobalOnLayoutListener(this);
}
}
});
/*Fragment f = new GridViewFragment();
FragmentTransaction t = getFragmentManager().beginTransaction();
t.replace(R.id.main_home_frag, f);
t.commit();*/
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* Adapter class
*
* This adapter class sets up GridFragment objects to be displayed by a
* ViewPager.
*/
public static class MyAdapter extends FragmentStatePagerAdapter implements IconPagerAdapter {
private TopicList mTopicList;
private int mNumItems = 0;
private int mNumFragments = 0;
/**
* Return a new adapter.
*/
public MyAdapter(FragmentManager fm, TopicList db, Resources res) {
super(fm);
setup(db, res);
}
/**
* Get the number of fragments to be displayed in the ViewPager.
*/
#Override
public int getCount() {
Log.i(TAG, "getCount : mNumFragments = "+mNumFragments);
return mNumFragments;
}
/**
* Return a new GridFragment that is used to display n items at the
* position given.
*
* #param position
* int - the position of the fragement; 0..numFragments-1
*/
#Override
public Fragment getItem(int position) {
// Create a new Fragment and supply the fragment number, image
// position, and image count as arguments.
// (This was how arguments were handled in the original pager
// example.)
Bundle args = new Bundle();
args.putInt("num", position + 1);
args.putInt("firstImage", position * mNumItems);
// The last page might not have the full number of items.
int imageCount = mNumItems;
if (position == (mNumFragments - 1)) {
int numTopics = mTopicList.getNumTopics();
int rem = numTopics % mNumItems;
if (rem > 0)
imageCount = rem;
}
args.putInt("imageCount", imageCount);
args.putSerializable("topicList", TopicList.getInstance());
// Return a new GridFragment object.
Log.i(TAG, "created fragmenat number:==== "+position+" "+1);
GridViewFragmentPhone f = new GridViewFragmentPhone();
f.setArguments(args);
Log.i(TAG, "getItem : imageCount = "+imageCount);
return f;
}
/**
* Set up the adapter using information from a TopicList and resources
* object. When this method completes, all the instance variables of the
* adapter are valid;
*
* #param tlist
* TopicList
* #param res
* Resources
* #return void
*/
void setup(TopicList tlist, Resources res) {
mTopicList = tlist;
if ((tlist == null) || (res == null)) {
mNumItems = 2;//DEFAULT_NUM_ITEMS;
mNumFragments = 2;//DEFAULT_NUM_FRAGMENTS;
} else {
int numTopics = tlist.getNumTopics();
int numRowsGV = res.getInteger(R.integer.num_of_rows_gridview);
int numColsGV = res.getInteger(R.integer.num_of_cols_gridview);
int numTopicsPerPage = numRowsGV * numColsGV;
int numFragments = numTopics / numTopicsPerPage;
if (numTopics % numTopicsPerPage != 0)
numFragments++; // Add one if there is a partial page
mNumFragments = numFragments;
mNumItems = numTopicsPerPage;
}
} // end setup
#Override
public int getIconResId(int index) {
int[] ICON = new int[mNumFragments];
for (int i = 0; i < mNumFragments; i++) {
ICON[i] = R.drawable.slidericon;
}
return ICON[index % ICON.length];
}
} // end class MyAdapter
#Override
public void onGridViewVisibilityChanged(boolean hide) {
if(hide){
homeFragmentLL.setVisibility(View.GONE);
}else {
homeFragmentLL.setVisibility(View.VISIBLE);
}
}
#Override
public void onDetach() {
super.onDetach();
activity = null;
}
#Override
public void onDestroy() {
super.onDestroy();
}
private class CmsPropertyAsync extends AsyncTask<String, Void, String> {
MainActivity context;
CmsPropertyAsync(MainActivity activityTab) {
context = activityTab;
}
#Override
protected String doInBackground(String... params) {
String propertyId = UConnectUtils.getPropertyId(PreferenceManager.getDefaultSharedPreferences(context),getResources().getString(R.string.property_id));
if(propertyId != null && propertyId.length() > 0){
return propertyId;
}
return UConnectUtils.requestPropertyId(params[0], params[1]);
}
#Override
protected void onPostExecute(String propertyId) {
if(propertyId == null){
indiacatorDialog.dismiss();
showPropertyIdTimeoutAlert(getActivity());
return;
}
SharedPreferences.Editor editor = PreferenceManager.getDefaultSharedPreferences(context).edit();
editor.putString(getString(R.string.property_id),propertyId).commit();
String url = null;
String locale = Locale.getDefault().getLanguage();
url = UCConstants.CMS_BASE_URL+"mainMenu?propertyId="+propertyId+"&lang="+locale;
JsonObjectRequest jsObjRequest = new JsonObjectRequest(
Request.Method.GET, url, null, new Response.Listener<JSONObject>() {
#Override
public void onResponse(JSONObject response) {
parseJson(response);
indiacatorDialog.dismiss();
}
}, new Response.ErrorListener() {
#Override
public void onErrorResponse(VolleyError error) {
if (activity != null) {
// activity.getConnection(error);
}
indiacatorDialog.dismiss();
}
});
ImageCacheManager.getInstance().getQueueForMainmenu().add(jsObjRequest);
}
}
private void indicatorAnim() {
if (indiacatorDialog != null) {
ImageView alertIndicator = (ImageView) indiacatorDialog.findViewById(R.id.alert_indicator);
alertIndicator.startAnimation(mRotateAnim);
if (!getActivity().isFinishing()) {
indiacatorDialog.show();
}
}
}
// Show alert for Time out
private void showPropertyIdTimeoutAlert(final Activity context) {
AlertDialog.Builder alertDialog = new AlertDialog.Builder(context);
alertDialog.setIcon(R.drawable.alert_dialog_icon);
alertDialog.setTitle(context.getString(R.string.timeout_msg));
alertDialog.setMessage(context.getString(R.string.timeout_msg2));
alertDialog.setPositiveButton("OK",
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
indicatorAnim();
// for property id
new CmsPropertyAsync(activity).execute(UCConstants.CMS_CONFIG_URL, UCConstants.CMS_CONFIG_KEY);
}
});
alertDialog.setNegativeButton("Cancel", new OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
getActivity().finish();
}
});
AlertDialog alert = alertDialog.create();
alert.setCancelable(false);
alert.setCanceledOnTouchOutside(false);
if (context != null && !context.isFinishing()) {
alert.show();
}
}
}

Actually, some data is being saved with onSavedInstaceState(). The data is not being deleted when process has been killed on LowMemory.
I fixed this with
#Override
protected void onSaveInstanceState(Bundle outState) {
//super.onSaveInstanceState(outState);
}
Just do not call super class. Just comment like above