android - My project cant see send or received messages -

it keeps crashing @ 1 point on 2 activities:

@override protected void onpostcreate(bundle savedinstancestate) {     super.onpostcreate(savedinstancestate);     activityutilities.customiseactionbar(this);  } 

my activityutilities.customiseactionbar leads to:

public class activityutilities {      public static void customiseactionbar(activity activity)     {         int titleid = 0;          if(build.version.sdk_int>=build.version_codes.lollipop)             titleid = activity.getresources().getidentifier("action_bar_title", "id", "android");         else             titleid = r.id.action_bar_title;          if(titleid>0){             textview titleview = (textview) activity.findviewbyid(titleid);             titleview.settextsize(22);         }     }  } 

the error code i'm getting is:

11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime: fatal exception: main 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime: process: com.ajapps.app, pid: 17854 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime: java.lang.runtimeexception: unable start activity componentinfo{com.ajapps.app/com.ajapps.app.wifichat.login}: java.lang.nullpointerexception: attempt invoke virtual method 'void android.widget.textview.settextsize(float)' on null object reference 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.app.activitythread.performlaunchactivity(activitythread.java:3119) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.app.activitythread.handlelaunchactivity(activitythread.java:3218) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.app.activitythread.access$1000(activitythread.java:198) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.app.activitythread$h.handlemessage(activitythread.java:1676) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.os.handler.dispatchmessage(handler.java:102) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.os.looper.loop(looper.java:145) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.app.activitythread.main(activitythread.java:6837) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ java.lang.reflect.method.invoke(native method) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ java.lang.reflect.method.invoke(method.java:372) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1404) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ com.android.internal.os.zygoteinit.main(zygoteinit.java:1199) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:  caused by: java.lang.nullpointerexception: attempt invoke virtual method 'void android.widget.textview.settextsize(float)' on null object reference 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ com.ajapps.app.wifichat.util.activityutilities.customiseactionbar(activityutilities.java:23) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ com.ajapps.app.wifichat.login.onpostcreate(login.java:95) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.app.instrumentation.callactivityonpostcreate(instrumentation.java:1201) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.app.activitythread.performlaunchactivity(activitythread.java:3101) 11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.app.activitythread.handlelaunchactivity(activitythread.java:3218)  11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.app.activitythread.access$1000(activitythread.java:198)  11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.app.activitythread$h.handlemessage(activitythread.java:1676)  11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.os.handler.dispatchmessage(handler.java:102)  11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.os.looper.loop(looper.java:145)  11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ android.app.activitythread.main(activitythread.java:6837)  11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ java.lang.reflect.method.invoke(native method)  11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ java.lang.reflect.method.invoke(method.java:372)  11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1404)  11-01 16:19:40.991 17854-17854/com.ajapps.app e/androidruntime:     @ com.android.internal.os.zygoteinit.main(zygoteinit.java:1199)  

if remove activityutilities.customiseactionbar, works fine app won't receive message.

chatactivity:

public class chatactivity extends activity { private static final string tag = "chatactivity";    private static final int pick_image = 1; private static final int take_photo = 2; private static final int record_audio = 3; private static final int record_video = 4; private static final int choose_file = 5; private static final int drawing = 6; private static final int download_image = 100; private static final int delete_message = 101; private static final int download_file = 102; private static final int copy_text = 103; private static final int share_text = 104;  private wifip2pmanager mmanager; private channel mchannel; private wifidirectbroadcastreceiver mreceiver; private intentfilter mintentfilter; private edittext edit; private static listview listview; private static list<message> listmessage; private static chatadapter chatadapter; private uri fileuri; private string fileurl; private arraylist<uri> tmpfilesuri;   @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_chat);      mmanager = (wifip2pmanager) getsystemservice(context.wifi_p2p_service);     mchannel = mmanager.initialize(this, getmainlooper(), null);     mreceiver = wifidirectbroadcastreceiver.createinstance();     mreceiver.setmactivity(this);      mintentfilter = new intentfilter();     mintentfilter.addaction(wifip2pmanager.wifi_p2p_state_changed_action);     mintentfilter.addaction(wifip2pmanager.wifi_p2p_peers_changed_action);     mintentfilter.addaction(wifip2pmanager.wifi_p2p_connection_changed_action);     mintentfilter.addaction(wifip2pmanager.wifi_p2p_this_device_changed_action);      //start service receive message     startservice(new intent(this, messageservice.class));      //initialize adapter chat     listview = (listview) findviewbyid(r.id.messagelist);     listmessage = new arraylist<message>();     chatadapter = new chatadapter(this, listmessage);     listview.setadapter(chatadapter);      //initialize list of temporary files uri     tmpfilesuri = new arraylist<uri>();      //send message     addfloatingactionbutton button = (addfloatingactionbutton) findviewbyid(r.id.sendmessage);     edit = (edittext) findviewbyid(r.id.editmessage);     button.setonclicklistener(new onclicklistener() {          @override         public void onclick(view arg0) {             if(!edit.gettext().tostring().equals("")){                 log.v(tag, "send message");                 sendmessage(message.text_message);             }                            else{                 toast.maketext(chatactivity.this, "please enter not empty message", toast.length_short).show();             }         }     });      //register context menu list view (for pop menu)     registerforcontextmenu(listview); }  @override protected void onpostcreate(bundle savedinstancestate) {     super.onpostcreate(savedinstancestate);      activityutilities.customiseactionbar(this); }  @override public void onresume() {     super.onresume();     registerreceiver(mreceiver, mintentfilter);              mmanager.discoverpeers(mchannel, new wifip2pmanager.actionlistener() {          @override         public void onsuccess() {             log.v(tag, "discovery process succeeded");         }          @override         public void onfailure(int reason) {             log.v(tag, "discovery process failed");         }     });     savestateforeground(true); }  @override public void onpause() {     super.onpause();     unregisterreceiver(mreceiver);     savestateforeground(false); }      @override public void onbackpressed() {     alertdialog.builder newdialog = new alertdialog.builder(this);     newdialog.settitle("close chatroom");     newdialog.setmessage("are sure want close chatroom?\n"             + "you no longer able receive messages, , "             + "all unsaved media files deleted.\n"             + "if host, other users disconnected well.");      newdialog.setpositivebutton("yes", new dialoginterface.onclicklistener(){          @override         public void onclick(dialoginterface dialog, int which) {             cleartmpfiles(getexternalfilesdir(null));             if(login.server!=null){                 login.server.interrupt();             }                    android.os.process.killprocess(android.os.process.mypid());          }      });      newdialog.setnegativebutton("cancel", new dialoginterface.onclicklistener() {          @override         public void onclick(dialoginterface dialog, int which) {             dialog.cancel();         }     });      newdialog.show(); }  @override protected void ondestroy() {     super.onstop();     cleartmpfiles(getexternalfilesdir(null)); }  // handle data sent 'for result' activities (pick/take image, record audio/video) @override protected void onactivityresult(int requestcode, int resultcode, intent data) {     super.onactivityresult(requestcode, resultcode, data);      switch(requestcode){         case pick_image:             if (resultcode == result_ok && data.getdata() != null) {                 fileuri = data.getdata();                 sendmessage(message.image_message);                              }             break;         case take_photo:             if (resultcode == result_ok && data.getdata() != null) {                 fileuri = data.getdata();                 sendmessage(message.image_message);                 tmpfilesuri.add(fileuri);             }             break;         case record_audio:             if (resultcode == result_ok) {                 fileurl = (string) data.getstringextra("audiopath");                 sendmessage(message.audio_message);             }             break;         case record_video:             if (resultcode == result_ok) {                 fileuri = data.getdata();                 fileurl = mediafile.getrealpathfromuri(this, fileuri);                 sendmessage(message.video_message);             }             break;         case choose_file:             if (resultcode == result_ok) {                 fileurl = (string) data.getstringextra("filepath");                 sendmessage(message.file_message);             }             break;         case drawing:             if(resultcode == result_ok){                 fileurl = (string) data.getstringextra("drawingpath");                 sendmessage(message.drawing_message);             }             break;     } }  // hydrate message object launch asynctasks send public void sendmessage(int type){     log.v(tag, "send message starts");     // message written in edittext sent     message mes = new message(type, edit.gettext().tostring(), null, login.chatname);      switch(type){         case message.image_message:             image image = new image(this, fileuri);             log.v(tag, "bitmap url ok");             mes.setbytearray(image.bitmaptobytearray(image.getbitmapfromuri()));                             mes.setfilename(image.getfilename());             mes.setfilesize(image.getfilesize());                            log.v(tag, "set byte array image ok");             break;         case message.audio_message:             mediafile audiofile = new mediafile(this, fileurl, message.audio_message);             mes.setbytearray(audiofile.filetobytearray());             mes.setfilename(audiofile.getfilename());             mes.setfilepath(audiofile.getfilepath());             break;         case message.video_message:             mediafile videofile = new mediafile(this, fileurl, message.audio_message);             mes.setbytearray(videofile.filetobytearray());             mes.setfilename(videofile.getfilename());             mes.setfilepath(videofile.getfilepath());             tmpfilesuri.add(fileuri);             break;         case message.file_message:             mediafile file = new mediafile(this, fileurl, message.file_message);             mes.setbytearray(file.filetobytearray());             mes.setfilename(file.getfilename());             break;         case message.drawing_message:             mediafile drawingfile = new mediafile(this, fileurl, message.drawing_message);             mes.setbytearray(drawingfile.filetobytearray());             mes.setfilename(drawingfile.getfilename());             mes.setfilepath(drawingfile.getfilepath());             break;     }            log.v(tag, "message object hydrated");      log.v(tag, "start asynctasks send message");     if(mreceiver.isgroupeowner() == wifidirectbroadcastreceiver.is_owner){         log.v(tag, "message hydrated, start sendmessageserver asynctask");         new sendmessageserver(chatactivity.this, true).executeonexecutor(asynctask.thread_pool_executor, mes);     }     else if(mreceiver.isgroupeowner() == wifidirectbroadcastreceiver.is_client){         log.v(tag, "message hydrated, start sendmessageclient asynctask");         new sendmessageclient(chatactivity.this, mreceiver.getowneraddr()).executeonexecutor(asynctask.thread_pool_executor, mes);     }             edit.settext(""); }  // refresh message list public static void refreshlist(message message, boolean ismine){     log.v(tag, "refresh message list starts");      message.setmine(ismine);      listmessage.add(message);     chatadapter.notifydatasetchanged();      log.v(tag, "chat adapter notified of changes");      //scroll last element of list     listview.setselection(listmessage.size() - 1); }     // save app's state (foreground or background) sharedprefereces public void savestateforeground(boolean isforeground){     sharedpreferences prefs = preferencemanager.getdefaultsharedpreferences(this);     editor edit = prefs.edit();     edit.putboolean("isforeground", isforeground);     edit.commit(); }  @override public boolean oncreateoptionsmenu(menu menu) {     getmenuinflater().inflate(r.menu.chat, menu);     return true; }  // handle click on menu @override public boolean onoptionsitemselected(menuitem item) {     int iditem = item.getitemid();     switch(iditem){         case r.id.send_image:             showpopup(edit);             return true;          case r.id.send_audio:             log.v(tag, "start activity record audio");             startactivityforresult(new intent(this, recordaudioactivity.class), record_audio);             return true;          case r.id.send_video:             log.v(tag, "start activity record video");             intent takevideointent = new intent(mediastore.action_video_capture);             takevideointent.putextra(mediastore.extra_video_quality, 0);             if (takevideointent.resolveactivity(getpackagemanager()) != null) {                 startactivityforresult(takevideointent, record_video);             }             return true;          case r.id.send_file:             log.v(tag, "start activity choose file");             intent choosefileintent = new intent(this, filepickeractivity.class);             startactivityforresult(choosefileintent, choose_file);             return true;          case r.id.send_drawing:             log.v(tag, "start activity draw");             intent drawintent = new intent(this, drawingactivity.class);             startactivityforresult(drawintent, drawing);             return true;          default:             return super.onoptionsitemselected(item);                }   }     //show popup menu public void showpopup(view v) {     popupmenu popup = new popupmenu(this, v);     popup.setonmenuitemclicklistener(new onmenuitemclicklistener() {          @override         public boolean onmenuitemclick(menuitem item) {             switch(item.getitemid()){             case r.id.pick_image:                 log.v(tag, "pick image");                 intent intent = new intent(intent.action_pick);                 intent.settype("image/*");                 intent.setaction(intent.action_get_content);                  // prevent crash if no app can handle intent                 if (intent.resolveactivity(getpackagemanager()) != null) {                     startactivityforresult(intent, pick_image);                 }                 break;              case r.id.take_photo:                 log.v(tag, "take photo");                 intent intent2 = new intent(mediastore.action_image_capture);                  if (intent2.resolveactivity(getpackagemanager()) != null) {                     startactivityforresult(intent2, take_photo);                 }                                    break;             }             return true;         }     });     popup.inflate(r.menu.send_image);     popup.show(); }  //create pop menu image download, delete message, etc... @override public void oncreatecontextmenu(contextmenu menu, view v, contextmenuinfo menuinfo) {     super.oncreatecontextmenu(menu, v, menuinfo);     menu.setheadertitle("options");      adaptercontextmenuinfo info = (adaptercontextmenuinfo) menuinfo;     message mes = listmessage.get((int) info.position);      //option delete message independently of type     menu.add(0, delete_message, menu.none, "delete message");      if(!mes.getmtext().equals("")){         //option copy message's text clipboard         menu.add(0, copy_text, menu.none, "copy message text");         //option share message's text         menu.add(0, share_text, menu.none, "share message text");     }              int type = mes.getmtype();     switch(type){         case message.image_message:             menu.add(0, download_image, menu.none, "download image");             break;         case message.file_message:             menu.add(0, download_file, menu.none, "download file");             break;         case message.audio_message:             menu.add(0, download_file, menu.none, "download audio file");             break;         case message.video_message:             menu.add(0, download_file, menu.none, "download video file");             break;         case message.drawing_message:             menu.add(0, download_file, menu.none, "download drawing");             break;     } }  //handle click event on pop menu @override public boolean oncontextitemselected(menuitem item) {     adaptercontextmenuinfo info = (adaptercontextmenuinfo) item.getmenuinfo();      switch (item.getitemid()) {         case download_image:             downloadimage(info.id);             return true;          case delete_message:             deletemessage(info.id);             return true;          case download_file:             downloadfile(info.id);             return true;          case copy_text:             copytexttoclipboard(info.id);             return true;          case share_text:             sharemedia(info.id, message.text_message);             return true;          default:             return super.oncontextitemselected(item);     } }  //download image , save downloads public void downloadimage(long id){       message mes = listmessage.get((int) id);     bitmap bm = mes.bytearraytobitmap(mes.getbytearray());           string path = environment.getexternalstoragepublicdirectory(environment.directory_downloads).getabsolutepath();      fileutilities.saveimagefrombitmap(this, bm, path, mes.getfilename());     fileutilities.refreshmedialibrary(this); }  //download file , save downloads public void downloadfile(long id){     message mes = listmessage.get((int) id);     string sourcepath = mes.getfilepath();     string destinationpath = environment.getexternalstoragepublicdirectory(environment.directory_downloads).getabsolutepath();      fileutilities.copyfile(this, sourcepath, destinationpath, mes.getfilename());     fileutilities.refreshmedialibrary(this); }  //delete message message list (doesn't delete on other phones) public void deletemessage(long id){     listmessage.remove((int) id);     chatadapter.notifydatasetchanged(); }  private void cleartmpfiles(file dir){     file[] childdirs = dir.listfiles();      for(file child : childdirs){         if(child.isdirectory()){             cleartmpfiles(child);         }         else{             child.delete();         }     }     for(uri uri: tmpfilesuri){         getcontentresolver().delete(uri, null, null);     }     fileutilities.refreshmedialibrary(this); }  public void talkto(string destination){     edit.settext("@" + destination + " : ");     edit.setselection(edit.gettext().length()); }  private void copytexttoclipboard(long id){     message mes = listmessage.get((int) id);     clipboardmanager clipboard = (clipboardmanager) getsystemservice(clipboard_service);      clipdata clip = clipdata.newplaintext("message", mes.getmtext());     clipboard.setprimaryclip(clip);     toast.maketext(this, "message copied clipboard", toast.length_short).show(); }  private void sharemedia(long id, int type){     message mes = listmessage.get((int) id);      switch(type){         case message.text_message:             intent sendintent = new intent();             sendintent.setaction(intent.action_send);             sendintent.putextra(intent.extra_text, mes.getmtext());             sendintent.settype("text/plain");             startactivity(sendintent);     }        } 

}

can try below code

getwindow().getdecorview().findviewbyid(titleid)