java - Marshmallow permissions and explanation -

could explain me plaese how should explain user permission

i work camera2api , implement such snippet of code ask permishion dinamicly

private void opencamera(int width, int height) {     setupcameraoutputs(width, height);     camerahelper.configuretransform(width, height, textureview, previewsize, getactivity());     cameramanager manager = (cameramanager) getsystemservice(context.camera_service);      try {         if (!cameraopencloselock.tryacquire(2500, timeunit.milliseconds)) {             throw new runtimeexception("time out waiting lock camera opening.");         }          if (activitycompat.checkselfpermission(this, manifest.permission.camera) !=                 packagemanager.permission_granted) {              // should show explanation?             if (activitycompat.shouldshowrequestpermissionrationale(this, manifest.permission.camera)) {                  // show explanation user *asynchronously* -- don't block                 // thread waiting user's response! after user                 // sees explanation, try again request permission.              } else {                 // no explanation needed, can request permission.                  activitycompat.requestpermissions(                         getactivity(), new string[]{android.manifest.permission.camera},                         my_permissions_request);                  // my_permissions_request                 // app-defined int constant. callback method gets                 // result of request.             }         }          manager.opencamera(mcameraid, mstatecallback, mbackgroundhandler);     } catch (cameraaccessexception e) {         e.printstacktrace();     } catch (interruptedexception e) {         throw new runtimeexception("interrupted while trying lock camera opening.", e);     } } 

according google docks should check if user deny permission before

there method return true of false

shouldshowrequestpermissionrationale(); 

and according google

this method returns true if app has requested permission , user denied request.

if understand correctly according google comments inside method implementation

// show explanation user asynchronously -- don't block

// thread waiting user's response! after user

// sees explanation, try again request permission.

and example user deny permission before , next time when go screen camera app should create castom pop-up explanation "please agree permishion if want continue" , example user agree time , should recall method again according this

// sees explanation, try again request permission.

but method

shouldshowrequestpermissionrationale(); 

return me true again, because didn't know user intent agree permission.

could explain me please how make way? maybe have example?

eventually find solution halp of @nuuneoi, lot!

and implement this

public void camera(view view) {     tocamera(); }  private void tocamera() {     if (!ischeckpermission()){         return;     }      if (isprocesswasfinish()) {         startactivity(new intent(getapplicationcontext(), cameraactivity.class));         overridependingtransition(r.anim.open_next, r.anim.close_main);     } else {         startactivity(new intent(getapplicationcontext(), userdatascreen.class));         overridependingtransition(r.anim.open_next, r.anim.close_main);     } }  private boolean ischeckpermission() {     if (activitycompat.checkselfpermission(this, manifest.permission.camera) !=             packagemanager.permission_granted) {          // should show explanation?         if (activitycompat.shouldshowrequestpermissionrationale(this, manifest.permission.camera)) {             showmessageokcancel("you need allow access camera");             return false;         }          // no explanation needed, can request permission.          activitycompat.requestpermissions(this, new string[]{android.manifest.permission.camera},                 my_permissions_request);         return false;         // my_permissions_request         // app-defined int constant. callback method gets         // result of request.     }      return true; }  private void showmessageokcancel(string message) {     new alertdialog.builder(mainactivity.this)             .setmessage(message)             .setpositivebutton("ok", listener)             .setnegativebutton("cancel", listener)             .create()             .show(); }  dialoginterface.onclicklistener listener = new dialoginterface.onclicklistener() {      final int button_negative = -2;     final int button_positive = -1;      @override     public void onclick(dialoginterface dialog, int which) {         switch (which) {             case button_negative:                 // int = -2                 dialog.dismiss();                 break;              case button_positive:                 // int = -1                 activitycompat.requestpermissions(                         mainactivity.this, new string[]{android.manifest.permission.camera},                         my_permissions_request);                 dialog.dismiss();                 break;         }     } };  @override public void onrequestpermissionsresult(int requestcode, @nonnull string[] permissions,                                        @nonnull int[] grantresults) {     switch (requestcode) {         case my_permissions_request: {             // if request cancelled, result arrays empty.             if (grantresults.length > 0                     && grantresults[0] == packagemanager.permission_granted) {                 log.e(my_log, "camera permission granted");                 // permission granted, yay!                 // contacts-related task need do.                  tocamera();              } else {                 log.e(my_log, "camera permission denied");                 // permission denied, boo! disable                 // functionality depends on permission.             }         }         default: {             super.onrequestpermissionsresult(requestcode, permissions, grantresults);         }          // other 'case' lines check other         // permissions app might request     } }