java - Android bugs on device. What should I do to fix them? -

in application noticed these 3 things:

-the button enabled when going 1 activity enabling user click on original activity. problem don't want user click on @ point in application. don't want disable button in application, when 1 intent called. how can that?

-i noticed strange... when toast notification pops in application until exit application. when exit application, of toast notifications residual , popping outside of application. there reason that? did miss in activity lifecycle handle cancellation of toasts @ point?

lastly, 1 rather tough solve. how lock screen when user rotates device, activity doesn't not called again , asynctask can still resume without starting on again?

thanks lot time. curious why these things happen , should into?

here's code:

//main activity.java  package com.example.patient_device;  import android.app.activity; import android.app.progressdialog; import android.content.context; import android.content.intent; import android.database.sqlite.sqlitedatabase; import android.os.asynctask; import android.os.bundle; import android.view.view; import android.widget.button;  import java.io.*;   public class mainactivity extends activity {      //fields     private progressdialog progressbar;     private context context;       /**      * called when activity first created.      */     @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.start_setup);         //set context         context = this;          //initialize start setup button , add onclick event listener button         final button start_setup_button = (button) findviewbyid(r.id.start_setup_button);         start_setup_button.setonclicklistener(new view.onclicklistener() {             public void onclick(view view) {                  //executes asynctask                 new retrieveinfotask().execute();                  //instantiates intent launch new activity                 intent myintent = new intent(mainactivity.this, retrieveinfoactivity.class);                 mainactivity.this.startactivity(myintent);              }         });     }      public class retrieveinfotask extends asynctask<void, void, void> {          //called on ui thread execute progress bar         @override         protected void onpreexecute() {             super.onpreexecute();              progressbar = new progressdialog(context);             progressbar.setindeterminate(true);             progressbar.setcancelable(false);             progressbar.setmessage(mainactivity.this.getstring(r.string.retrieve_info));             progressbar.show();         }          //methods retrieves information user device. performed in background thread         private void retrieveinfo() {              try {                  //reading drawable resource line line                 string str="";                 stringbuffer buf = new stringbuffer();                 inputstream = mainactivity.this.getresources().openrawresource(r.drawable.user_info);                 bufferedreader reader = new bufferedreader(new inputstreamreader(is));                 if (is!=null) {                     while ((str = reader.readline()) != null) {                         buf.append(str + "\n" );                     }                 }                 is.close();              } catch (exception e) {                 e.printstacktrace();             }         }           //doinbackground calls retrieveinfo() perform action in background         @override         protected void doinbackground(void... params) {              retrieveinfo();             return null;         }          //when background task done, dismiss progress bar         @override         protected void onpostexecute(void result) {             if (progressbar!=null) {                 progressbar.dismiss();             }         }       } }  //retrieveinfoactivity.java  package com.example.patient_device;  import android.app.activity; import android.content.broadcastreceiver; import android.content.context; import android.content.intent; import android.content.intentfilter; import android.content.res.resources; import android.os.batterymanager; import android.os.bundle; import android.util.log; import android.widget.textview; import android.widget.toast;  public class retrieveinfoactivity extends activity {      private static string tag = "retrieveinfoactivity";     private context context;     string filelastsync = "09-18-2014 03:47 pm";     @override    public void oncreate(bundle savedinstancestate) {              context = this;              super.oncreate(savedinstancestate);             setcontentview(r.layout.retrieve_info);              //once new activity launched, setup complete             toast.maketext(getapplicationcontext(), "setup complete!",                     toast.length_long).show();              //gets 'last synced' string , sets datetime of last sync             resources resources = context.getresources();             string syncstring = string.format(resources.getstring(r.string.last_sync), filelastsync);              //dynamically sets datetime of last sync string             textview lastsynctextview = ((textview) findviewbyid(r.id.last_sync) );             lastsynctextview.settext(syncstring);              //calls registerreceiver receive broadcast state of battery             this.registerreceiver(this.mbatinforeceiver,new                     intentfilter(intent.action_battery_changed));      }      private broadcastreceiver mbatinforeceiver = new broadcastreceiver()  {          @override         public void onreceive(context arg0, intent intent) {              //battery level             int level = intent.getintextra("level", 0);              //dynamically sets value of battery level             textview batterytextview = ((textview) findviewbyid(r.id.battery) );             batterytextview.settext("battery level: " + string.valueof(level)+ "%");              //if battery level drops below 25%, announce battery low             //todo: add 25 constants file.             if(level < 25) {                  toast.maketext(getapplicationcontext(), "low battery!",                         toast.length_long).show();               }             //plugged in status             int plugged = intent.getintextra(batterymanager.extra_plugged, -1);              //battery status             int status = intent.getintextra(batterymanager.extra_status, -1);              //if device charging or contains full status, it's charging             boolean ischarging = status == batterymanager.battery_status_charging ||                     status == batterymanager.battery_status_full;              //if device ischarging , plugged in, show battery charging             if(ischarging && plugged == batterymanager.battery_plugged_ac || plugged == batterymanager.battery_plugged_usb) {                  toast.maketext(getapplicationcontext(), "charging.." + string.valueof(level)+ "%",                         toast.length_long).show();              }else{                 toast.maketext(getapplicationcontext(), "unplugged!",                         toast.length_long).show();             }           }      };      @override     public void ondestroy() {          try {             super.ondestroy();             unregisterreceiver(this.mbatinforeceiver);         }         catch (exception e) {             log.e(retrieveinfoctivity.tag, getclass() + " releasing receivers-" + e.getmessage());         }      }  }  //startsetupactivity.java   import android.app.activity; import android.content.intent; import android.os.bundle; import android.view.view; import android.widget.button;  public class startsetupactivity extends activity {      @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);       } }  //fragmentsactivity.java   import android.app.fragment; import android.os.bundle; import android.view.layoutinflater; import android.view.view; import android.view.viewgroup;  public class fragmentsactivity extends fragment{     @override     public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) {          return inflater.inflate(r.layout.main, container, false);     } } 

first of whenever want disable press override onbackpressed() method , remove super. this:

@override public void onbackpressed() {     //super.onbackpressed(); } 

second you'r using application context show toast. use activity context.

toast.maketext(this or youractivity.this, "setup complete!", toast.length_long).show(); 

third add attribute manifest class. avoid recrating activity when orientation change

android:configchanges="orientation"