java - App randomly crashing, MainActivity session error occurs -

sometimes application run slow , messes up. attached main activity , manifest, think 1 of making application mess up. gives me error : session 'mainactivity': error.

any appreciated.

thank you.

main activity

import graphics.myglsurfaceview; import gameinfo.gamedatabase;  public class mainactivity extends actionbaractivity {      //runs before application created     private button mcampaignbutton;     private context context = this;     private glsurfaceview mglview;      //when application created     @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);          //new thread perform database creation / filling         runnable runnable = new runnable(){         public void run(){             //instantiate gamedatabase object (this activity)             final gamedatabase gdb = new gamedatabase(context);              gdb.fillgamedatabase();         }     };      thread mythread = new thread(runnable);     mythread.start();      mglview = new myglsurfaceview(this);     setcontentview(mglview);      //keeps screen on doesn't fall asleep     getwindow().addflags(windowmanager.layoutparams.flag_keep_screen_on);      //finding button button id after application created     mcampaignbutton = (button)findviewbyid(r.id.campaignbuttonid);      //checks if campaign button clicked     mcampaignbutton.setonclicklistener(new view.onclicklistener() {         @override         public void onclick(view v) {              //intent go main activity campaign level select activity             final intent intent = new intent(mainactivity.this, campaignselectlevel.class);              startactivity(intent);          }     });     }      } 

android manifest

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="tekvision.codedecrypter"> <!-- tell system app requires opengl es 2.0. -->     <uses-feature         android:glesversion="0x00020000"         android:required="true" />     <supports-gl-texture android:name="gl_oes_compressed_etc1_rgb8_texture" />     <application         android:allowbackup="true"         android:icon="@mipmap/ic_launcher"         android:label="@string/app_name"         android:theme="@style/apptheme"  >      <activity         android:name=".mainactivity"         android:label="@string/app_name" >         <intent-filter>             <action android:name="android.intent.action.main" />              <category android:name="android.intent.category.launcher" />         </intent-filter>     </activity>      <activity         android:name=".campaignselectlevel"         android:label="@string/title_activity_campaign_select_level" >     </activity>      <!-- anagrams.modern era java class different package-->     <activity android:name="anagrams.modern_era"               android:label="modern_era">      </activity>  </application> 

make sure declaring permissions in manifest file required application i.e.

    <uses-permission android:name="android.permission.write_external_storage"/> 

for more details check this: uses-permission