I have a problem with AsyncTask in android. I have a NullPointerException at this line
ConnectivityManager conMgr = (ConnectivityManager)
context.getSystemService(Context.CONNECTIVITY_SERVICE);
in this method
public static boolean checkRete(Context context) {
ConnectivityManager conMgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo infos[] = conMgr.getAllNetworkInfo();
for (NetworkInfo info : infos) {
if (info.getState() == State.CONNECTED)
return true;
}
return false;
}
This error causes a Runtime Exception while executing doInBackground() part of AsyncTask class.
protected ArrayList<ObjDb> doInBackground(Void... params) {
return Functions.query(act, "http://www.unishare.it/tutored/" + url);
}
This is the entire log of error:
04-06 18:06:40.082 25316-25365/it.polimi.mobilecourse.expenses E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #3
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:278)
at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
at java.util.concurrent.FutureTask.run(FutureTask.java:137)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
at java.lang.Thread.run(Thread.java:864)
Caused by: java.lang.NullPointerException
at it.polimi.mobilecourse.expenses.Functions.checkRete(Functions.java:36)
at it.polimi.mobilecourse.expenses.Functions.query(Functions.java:27)
at it.polimi.mobilecourse.expenses.RequestFtp.doInBackground(RequestFtp.java:33)
at it.polimi.mobilecourse.expenses.RequestFtp.doInBackground(RequestFtp.java:14)
at android.os.AsyncTask$2.call(AsyncTask.java:264)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
????????????at java.util.concurrent.FutureTask.run(FutureTask.java:137)
????????????at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
????????????at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
????????????at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
????????????at java.lang.Thread.run(Thread.java:864)
and these are other methods. The method checkRete() is called by:
static ArrayList<ObjDb> query(Context context, String url) {
System.out.println(url);
if(!checkRete(context)) {
System.out.println("Problema rete");
return null;
}
that is called by doInBackground(). I have already set the permission in Manifest for WiFi and 3g connection. Why I found this error? Please,help me!
Edit: context comes from this:
new RequestFtp().setParameters(activity, url, "controlloFB", LandingFragment.this).execute();
where setParameters sets context to activity that is a simple Activity.
Edit 2:
public class RequestFtp extends AsyncTask<Void,ArrayList<ObjDb>,ArrayList<ObjDb>> {
private String url;
private Fragment fragment;
private String op;
private HelpActivity act;
public RequestFtp setParameters(HelpActivity activity, String url,String op, Fragment fragment) {
this.url = url;
this.op=op;
this.act=activity;
this.fragment = fragment;
return this;
}
/** The system calls this to perform work in a worker thread and
* delivers it the parameters given to AsyncTask.execute() */
protected ArrayList<ObjDb> doInBackground(Void... params) {
return Functions.query(act, "http://www.unishare.it/tutored/" + url);
}
/** The system calls this to perform work in the UI thread and delivers
* the result from doInBackground() */
protected void onPostExecute(ArrayList<ObjDb> result) {
if(result == null) {
Toast.makeText(act.getApplicationContext(),R.string.error_connection,Toast.LENGTH_SHORT).show();
return;
}
act.handleResult(result,op,fragment);
}
}
Fragment:
public class LandingFragment extends Fragment {
private View view;
private LandingActivity activity;
private String str;
int id;
String nome;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
view = inflater.inflate(R.layout.landing_fragment, container, false);
buttonsActions();
return view;
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
this.activity = (LandingActivity) activity;
}
public void buttonsActions() {
Button butS = (Button) view.findViewById(R.id.buttonStudente);
butS.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent myintent = new Intent(v.getContext(), LoginStudente.class);
startActivity(myintent);
}
});
Button butT = (Button) view.findViewById(R.id.buttonTutor);
butT.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent myintent = new Intent(v.getContext(), LoginTutor.class);
startActivity(myintent);
}
});
}
private void buttonsSActions() {
Button butS = (Button) view.findViewById(R.id.buttonStudente);
butS.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent myintent = new Intent(v.getContext(), DataActivityStudent.class);
Bundle mBundle = new Bundle();
mBundle.putString("Nome", nome);
mBundle.putInt("Id", id);
myintent.putExtras(mBundle);
startActivity(myintent);
}
});
Button butT = (Button) view.findViewById(R.id.buttonTutor);
butT.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent myintent = new Intent(v.getContext(), LoginTutor.class);
startActivity(myintent);
}
});
try {
((manageListener) activity).manageButton();
}
catch(ClassCastException cce){
}
}
private void buttonsTActions() {
Button butS = (Button) view.findViewById(R.id.buttonStudente);
butS.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent myintent = new Intent(v.getContext(), LoginStudente.class);
startActivity(myintent);
}
});
Button butT = (Button) view.findViewById(R.id.buttonTutor);
butT.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent myintent = new Intent(v.getContext(), DataActivityTutor.class);
startActivity(myintent);
}
});
try {
((manageListener) activity).manageButton();
}
catch(ClassCastException cce){
}
}
public void ftpControl(String url) {
new RequestFtp().setParameters(activity, url, "controlloFB", LandingFragment.this).execute();
}
private void setNomeWelcome(String nome) {
WelcomeFragment wf = activity.getWf();
wf.setText(nome);
}
public void control(ArrayList<ObjDb> result) {
ObjDb res = result.get(0);
String response = res.get("Response");
//System.out.println("Response "+response);
if (response.compareTo("S") == 0) {
str = "S";
String id_utente = res.get("id_utente");
nome = res.get("nome");
//System.out.println("nome "+nome);
id = Integer.parseInt(id_utente);
buttonsSActions();
}
if (response.compareTo("T") == 0) {
str = "T";
String id_utente = res.get("id_utente");
nome = res.get("nome");
id = Integer.parseInt(id_utente);
buttonsTActions();
}
if (nome.compareTo("") != 0) {
setNomeWelcome(nome);
}
}
public interface manageListener{
public void manageButton();
}
}
Activity:
public class LandingActivity extends HelpActivity implements LandingFragment.manageListener {
private LandingFragment lf;
private WelcomeFragment wf;
private ProgressBar progressView;
private UiLifecycleHelper uiHelper;
private Session.StatusCallback callback;
String nome;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setLanding();
progress(true);
showWelcome();
manageSession(savedInstanceState);
}
private void manageSession(Bundle savedInstanceState){
callback=new Session.StatusCallback(){
@Override
public void call(final Session session,final SessionState state,final Exception exception){
onSessionStateChange(session, state, exception);
}
};
uiHelper = new UiLifecycleHelper(this,callback);
uiHelper.onCreate(savedInstanceState);
Settings.addLoggingBehavior(LoggingBehavior.INCLUDE_ACCESS_TOKENS);
Session session=Session.getActiveSession();
if(session.getPermissions().isEmpty()){
System.out.println("logged false");
FragmentManager fragMan = getFragmentManager();
FragmentTransaction fragTrans=fragMan.beginTransaction();
fragTrans.replace(R.id.fragreplace,lf).commit();
progress(false);
}
}
private void setLanding(){
setContentView(R.layout.landing_activity);
progressView=(ProgressBar)findViewById(R.id.progressBarRS);
lf=new LandingFragment();
wf=new WelcomeFragment();
}
@Override
public void onActivityResult(int requestCode,int resultCode,Intent data){
super.onActivityResult(requestCode,resultCode,data);
uiHelper.onActivityResult(requestCode,resultCode,data);
}
@Override
public void handleResult(ArrayList<ObjDb> result,String op,Fragment fragment){
if(result==null){
progress(false);
}
if(op=="controlloFB"){
LandingFragment lfr=(LandingFragment) fragment;
lfr.control(result);
}
}
private void onSessionStateChange(Session session, SessionState state, Exception exception) {
if(session==null || session.isClosed()){
Log.i("LandingActivity", "session nulla...");
}
if(session!=null && session.isOpened()){
Log.i("LandingActivity", "session not null...");
System.out.println(session.getPermissions());
new Request(session,"me",null, HttpMethod.GET,new Request.Callback(){
public void onCompleted(Response response){
String us=null;
try {
us=response.getGraphObject().getProperty("email").toString();
nome=response.getGraphObject()
