java - Before loading listview from json url, giving error at onQueryTextChange(),when applying getFilter() -

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• what nullpointerexception, , how fix it? 12 answers

i new in android development ,i have implemented searchfilter searchview. applied filter listview , giving me correct result. problem that, when listview still loading ...at time if click on search edit text,my app gets crash....

my code:

public class cityadapter extends baseadapter implements filterable {      valuefilter valuefilter;     private arraylist<city> citylist;     private arraylist<city> mstringfilterlist;     private context context;     private layoutinflater layoutinflater;      public cityadapter(context context, arraylist<city> citylist) {         this.context = context;         this.citylist = citylist;         mstringfilterlist = citylist;         layoutinflater = (layoutinflater) context.getsystemservice(context.layout_inflater_service);     }      @override     public int getcount() {         return citylist.size();     }      @override     public object getitem(int position) {         return citylist.get(position);     }      @override     public long getitemid(int position) {         return position;     }      @override     public filter getfilter() {         if (valuefilter == null) {             valuefilter = new valuefilter();         }         return valuefilter;     }      public class holder {         robototextview cityname_txt;         textview cityid_txt;     }      @override     public view getview(int position, view convertview, viewgroup parent) {         final holder holder;         if (convertview == null) {             holder = new holder();             convertview = layoutinflater.inflate(r.layout.city_list_item, null);             holder.cityname_txt = (robototextview) convertview.findviewbyid(r.id.citytxt);             holder.cityid_txt = (textview) convertview.findviewbyid(r.id.idtxt);              convertview.settag(holder);         } else {             holder = (holder) convertview.gettag();         }         holder.cityname_txt.settext(citylist.get(position).getcity_name());         holder.cityid_txt.settext(citylist.get(position).getcity_id());          return convertview;     }      private class valuefilter extends filter {         @override         protected filterresults performfiltering(charsequence constraint) {             filterresults results = new filterresults();              if (constraint != null && constraint.length() > 0) {                 arraylist<city> filterlist = new arraylist<city>();                 (int = 0; < mstringfilterlist.size(); i++) {                     if ((mstringfilterlist.get(i).getcity_name().touppercase())                             .contains(constraint.tostring().touppercase())) {                          city city = new city(mstringfilterlist.get(i)                                 .getcity_id(), mstringfilterlist.get(i)                                 .getcity_name());                          filterlist.add(city);                     }                 }                 results.count = filterlist.size();                 results.values = filterlist;             } else {                 results.count = mstringfilterlist.size();                 results.values = mstringfilterlist;             }             return results;          }          @override         protected void publishresults(charsequence constraint, filterresults results) {             citylist = (arraylist<city>) results.values;             notifydatasetchanged();         }      } } 

my activity code

search_view.setonquerytextlistener(this);         lv.setonitemclicklistener(new adapterview.onitemclicklistener() {             @override             public void onitemclick(adapterview<?> parent, view view, int position, long id) {                 string itemid = (string) lv.getitematposition(position).tostring();                 toast.maketext(context,"position="+itemid,toast.length_long).show();                 intent i_details = new intent(dharmshalacities.this, dharmshaladetailsactivity.class);                 i_details.putextra("itemid", itemid);                 startactivity(i_details);             }         });     }      @override     public boolean onquerytextsubmit(string query) {         return false;     }      @override     public boolean onquerytextchange(string newtext) {             cityadapter.getfilter().filter(newtext);          return false;     }  //and giving error line of code        //cityadapter.getfilter().filter(newtext); 

logcat error

06-16 07:22:19.326 23888-23888/com.newsoftsolutions.android.padamashligotram e/androidruntime: fatal exception: main process: com.newsoftsolutions.android.padamashligotram, pid: 23888 java.lang.nullpointerexception: attempt invoke virtual method 'android.widget.filter com.newsoftsolutions.android.padamashligotram.adapter.cityadapter.getfilter()' on null object reference @ com.newsoftsolutions.android.padamashligotram.dharmshalacities.onquerytextchange(dharmshalacities.java:76) @ android.widget.searchview.ontextchanged(searchview.java:1257) @ android.widget.searchview.access$2000(searchview.java:95) @ android.widget.searchview$11.ontextchanged(searchview.java:1737) @ android.widget.textview.sendontextchanged(textview.java:7749) @ android.widget.textview.handletextchanged(textview.java:7809) @ android.widget.textview$changewatcher.ontextchanged(textview.java:9727) @ android.text.spannablestringbuilder.sendtextchanged(spannablestringbuilder.java:964) @ android.text.spannablestringbuilder.replace(spannablestringbuilder.java:515) @ android.text.spannablestringbuilder.replace(spannablestringbuilder.java:454) @ android.text.spannablestringbuilder.replace(spannablestringbuilder.java:33) @ android.view.inputmethod.baseinputconnection.replacetext(baseinputconnection.java:685) @ android.view.inputmethod.baseinputconnection.committext(baseinputconnection.java:197) @ com.android.internal.widget.editableinputconnection.committext(editableinputconnection.java:184) @ com.android.internal.view.iinputconnectionwrapper.executemessage(iinputconnectionwrapper.java:286) @ com.android.internal.view.iinputconnectionwrapper$myhandler.handlemessage(iinputconnectionwrapper.java:78) @ android.os.handler.dispatchmessage(handler.java:102) @ android.os.looper.loop(looper.java:135) @ android.app.activitythread.main(activitythread.java:5289) @ java.lang.reflect.method.invoke(native method) @ java.lang.reflect.method.invoke(method.java:372) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:899) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:694) 06-16 07:22:20.643 23888-24385/com.newsoftsolutions.android.padamashligotram e/pass 1: connection success

 @override     public void onitemclick(adapterview<?> parent, view view, int position, long id) {          if (youradapter != null) {              string itemid = (string) lv.getitematposition(position).tostring();             toast.maketext(context, "position=" + itemid, toast.length_long).show();             intent i_details = new intent(dharmshalacities.this, dharmshaladetailsactivity.class);             i_details.putextra("itemid", itemid);             startactivity(i_details);         }     } 

change here too

 @override     public boolean onquerytextchange(string newtext) {     if (cityadapter != null) {         cityadapter.getfilter().filter(newtext);         }         return false;     }