android - flashlight not working on some devices -

i made simple flashlight app not working on devices camera led on others works fine. can tell me doing wrong?

here main activity:

public class mainactivity extends activity {      private camera camera;     private camera.parameters parameters;     private imagebutton flashlightbutton;     boolean isflashlighton = false;       @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);           adview madview = (adview) findviewbyid(r.id.adview);             adrequest adrequest = new adrequest.builder().build();             madview.loadad(adrequest);           flashlightbutton = (imagebutton)findviewbyid(r.id.flashlight_button);         flashlightbutton.setonclicklistener(new flashonofflistener());          if (isflashsupported()) {             camera = camera.open();             parameters = camera.getparameters();         } else {             shownoflashalert();         }     }        private class flashonofflistener implements view.onclicklistener{          @override         public void onclick(view v) {             if(isflashlighton){                 flashlightbutton.setimageresource(r.drawable.flashlight_off);                 parameters.setflashmode(parameters.flash_mode_off);                 camera.setparameters(parameters);                 camera.stoppreview();                 isflashlighton = false;             }else{                 flashlightbutton.setimageresource(r.drawable.flashlight_on);                 parameters.setflashmode(parameters.flash_mode_torch);                 camera.setparameters(parameters);                 camera.startpreview();                 isflashlighton = true;             }          }      }      private void shownoflashalert() {         new alertdialog.builder(this)                 .setmessage("your device hardware not support flashlight!")                 .seticon(android.r.drawable.ic_dialog_alert).settitle("error")                 .setpositivebutton("ok", new onclicklistener() {                      @override                     public void onclick(dialoginterface dialog, int which) {                         dialog.dismiss();                         finish();                     }                 }).show();     }      private boolean isflashsupported() {         packagemanager pm = getpackagemanager();         return pm.hassystemfeature(packagemanager.feature_camera_flash);     }      @override     protected void ondestroy() {         if(camera != null){             camera.stoppreview();             camera.release();             camera = null;         }         super.ondestroy();     } } 

the problem you're having has how manufacturers have different ways putting camera led in flashlight mode , how older devices running dated versions of android used enable led. samsung , htc have issues, simplest way go around use switch-case statements turn flashlight on/off different types of devices. question has been asked several times before way go search on here different ways of turning on flashlight different manufacturers , android versions. write logic gets device's attributes, tests them using switch-case or if-else , you're supposed each vendor. @ least, that's best way ensure full compatibility.