android - How to check Internet connection and spawn a Dialog if not connected -

my app internet based , when device has not got internet crashes due trying download files no success. have realised while typing if data requires goes offline crash. have tried reading documentation , trying add app appears need different have been reading.

• add 'no internet connection' dialog preferably on activity , not via toast.
• add 'data unavailable' dialog fragment within toast

i use mainactivity load fragments doubt put kind of code in show dialog on fragment's used area. either way add mainactivity , internet loading fragment.

mainactivity.class:

public class mainactivity extends sherlockfragmentactivity {      private viewpager mviewpager;     private tabswipe mtabswipe;        @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         new firstlauncheula(this).show();            mviewpager = new viewpager(this);         mviewpager.setid(r.id.pager);         mviewpager.setoffscreenpagelimit(2);         setcontentview(mviewpager);          final actionbar bar = getsupportactionbar();         bar.setnavigationmode(actionbar.navigation_mode_tabs);          mtabswipe = new tabswipe(this, mviewpager);         mtabswipe.addtab(bar.newtab().settext("games"), a_internet_service.class, null);         mtabswipe.addtab(bar.newtab().settext("movies"), test_fragment.class, null);         mtabswipe.addtab(bar.newtab().settext("tech"), purchase_fragment.class, null);       }  } 

a_internet_service.class:

public class a_fragment_service extends fragment {      // static variables     static final string url = "this.is.a.url";     // xml node keys     static final string key_data = "data"; // parent node     static final string key_id = "id";     static final string key_title = "title";     static final string key_date1 = "date1";     static final string key_date2 = "date2";     static final string key_date3 = "date3";     static final string key_date2vis = "date2vis";     static final string key_date3vis = "date3vis";     static final string key_platforms = "platforms";     static final string key_thumb_url = "thumb_url";       arraylist<hashmap<string, string>> songslist;     view view;      @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         new thetask().execute();         /*     // click event single list row     list.setonitemclicklistener(new onitemclicklistener() {           @override         public void onitemclick(adapterview<?> arg0, view arg1, int arg2,                 long arg3) {             // todo auto-generated method stub          }     }); */     }      @override     public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate){         view = inflater.inflate(r.layout.main, container, false);         //list = (listview) view.findviewbyid(r.id.data_list);         return view;      }      @override     public void onactivitycreated (bundle savedinstancestate) {         super.onactivitycreated(savedinstancestate);     }      class thetask extends asynctask<void, void, void> {          @override         protected void onpreexecute() {             // todo auto-generated method stub             super.onpreexecute();          }          @override         protected void doinbackground(void... params) {             xmlparser parser = new xmlparser();             string xml = parser.getxmlfromurl(url); // getting xml url             songslist = new arraylist<hashmap<string, string>>();             document doc = parser.getdomelement(xml); // getting dom element             nodelist nl = doc.getelementsbytagname(key_data);             (int = 0; < nl.getlength(); i++) {                 // creating new hashmap                 hashmap<string, string> map = new hashmap<string, string>();                 element e = (element) nl.item(i);                 // adding each child node hashmap key => value                 map.put(key_id, parser.getvalue(e, key_id));                 map.put(key_title, parser.getvalue(e, key_title));                 map.put(key_date1, parser.getvalue(e, key_date1));                 map.put(key_date2, parser.getvalue(e, key_date2));                 map.put(key_date3, parser.getvalue(e, key_date3));                 map.put(key_date2vis, parser.getvalue(e, key_date2vis));                 map.put(key_date3vis, parser.getvalue(e, key_date3vis));                 map.put(key_platforms, parser.getvalue(e, key_platforms));                 map.put(key_thumb_url, parser.getvalue(e, key_thumb_url));                  // adding hashlist arraylist                 songslist.add(map);             }             return null;         }          @override         protected void onpostexecute(void result) {             // getting adapter passing xml data arraylist             lazyadapter adapter = new lazyadapter(getactivity(), datalist);             view = getview();             listview mlist = (listview) view.findviewbyid(r.id.data_list);             mlist.setadapter(adapter);             super.onpostexecute(result);         }     }  } 

edited fragment section:

@override public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate){     view = inflater.inflate(r.layout.main, container, false);      return view;     if(!isconnected(getactivity())) builddialog(getactivity()).show();     else {         new thetask().execute();       }  }  public boolean isconnected(context context) {      connectivitymanager cm = (connectivitymanager) context.getsystemservice(context.connectivity_service);     networkinfo netinfo = cm.getactivenetworkinfo();      if (netinfo != null && netinfo.isconnectedorconnecting()) {         android.net.networkinfo wifi = cm.getnetworkinfo(connectivitymanager.type_wifi);         android.net.networkinfo mobile = cm.getnetworkinfo(connectivitymanager.type_mobile);          if((mobile != null && mobile.isconnectedorconnecting()) || (wifi != null && wifi.isconnectedorconnecting())) return true;         else return false;     } else         return false; }  public alertdialog.builder builddialog(context c) {      alertdialog.builder builder = new alertdialog.builder(c);     builder.settitle("no internet connection.");     builder.setmessage("you have no internet connection");      builder.setpositivebutton("ok", new dialoginterface.onclicklistener() {          @override         public void onclick(dialoginterface dialog, int which) {              dialog.dismiss();         }     });      return builder; } //all other code 

you example check internet connection this:

it return true if device has internet connection or have internet connection.

public boolean isconnected(context context) {          connectivitymanager cm = (connectivitymanager) context.getsystemservice(context.connectivity_service);         networkinfo netinfo = cm.getactivenetworkinfo();          if (netinfo != null && netinfo.isconnectedorconnecting()) {             android.net.networkinfo wifi = cm.getnetworkinfo(connectivitymanager.type_wifi);             android.net.networkinfo mobile = cm.getnetworkinfo(connectivitymanager.type_mobile);              if((mobile != null && mobile.isconnectedorconnecting()) || (wifi != null && wifi.isconnectedorconnecting())) return true;             else return false;         } else             return false;     } 

and how u use in application: (inside fragments oncreateview example, if device not connected, show dialog, see code below of how spawn simple dialog)

@override public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate){     view = inflater.inflate(r.layout.yourlayout, container, false);      // getactivity() hand on context method     // if call inside activity, replace getactivity() "this"     if(!isconnected(getactivity())) builddialog(getactivity()).show();     else {         // have internet connection, save connect internet here         new thetask().execute();     }      // other stuff     return view; }  public boolean isconnected(context context) {      connectivitymanager cm = (connectivitymanager) context.getsystemservice(context.connectivity_service);     networkinfo netinfo = cm.getactivenetworkinfo();      if (netinfo != null && netinfo.isconnectedorconnecting()) {         android.net.networkinfo wifi = cm.getnetworkinfo(connectivitymanager.type_wifi);         android.net.networkinfo mobile = cm.getnetworkinfo(connectivitymanager.type_mobile);          if((mobile != null && mobile.isconnectedorconnecting()) || (wifi != null && wifi.isconnectedorconnecting())) return true;         else return false;     } else return false; }  public alertdialog.builder builddialog(context c) {      alertdialog.builder builder = new alertdialog.builder(c);     builder.settitle("no internet connection.");     builder.setmessage("you have no internet connection");      builder.setpositivebutton("ok", new dialoginterface.onclicklistener() {          @override         public void onclick(dialoginterface dialog, int which) {              dialog.dismiss();         }     });      return builder; } 

this can done anywhere in code, example in oncreate() method of activity, or in oncreateview() method of fragment - wherever desire connect internet, check first - internet stuff.

don't forget permissions:

<uses-permission android:name="android.permission.access_wifi_state" /> <uses-permission android:name="android.permission.internet" /> <uses-permission android:name="android.permission.access_network_state" /> 

i hope helps ;)