1.b Android apps are built using four
essential blocks: Activities, Services, Broadcast receivers, and content providers which are described as follows.
An activity is the interfacing window through which user can interact with the
application such as performing the task, sending a message, and clicking the
photo. It also keeps track of user’s current activity, his/her previous
activities and gives priority accordingly. In addition, it provides a way to
the apps to apply a user flow among each other and thus serving system for managing such flows.
It is a starting point for any app which runs in the background and performs a required
operation or any other task for remote access. There are two different
services: started service and bound service which tells system regarding how to
manage the app. Started services can be playing a music in background or
syncing of data in the background. Here,
music playback service is a known to the user via notification hence system
gives it more resources in terms of keep running it. While in case of some
background service which is not known to the users can be killed by system or
get restarts later by the system in case of managing its process. Bound
services are those which has been requested by some other app or the system itself. Example of the bound services is notification listeners, accessibility
services, and live wallpapers.
receivers: It is an android element which responds
to system-wide declarations. For example, an app can give a scheduled alarm to
broadcast receiver and can go off
regardless of alarm’s status. The broadcast can be made from the system or from
the app such as data download, the battery is low, or a picture was taken.
Providers: It handles a common app data that one can store in file storage, on
the web, SQLite or any other desirable
location which can be accessed by the app. Further, through the content
provider, other apps can request or alter that data if it has been allowed by
the content provider. The content provider can similarly be spent for
analysis and entering data which is only acknowledged to that application.
1.c The various permissions can be
requested by an application which is as
It grants the application to use user’s current location which can be used for desired app operation such as
direction for the map, in fitness app and
It allows to access contacts stored in
the device which can be used for contacting the person from a different platform such as contact can be
synced and use on social apps such as WhatsApp, Instagram and so on.
It gives permission to use device’s camera to click the photo or shoot video or any other task such as video call.
It sanctions storage access permit, it means that it can access the device
content such as photo, video, documents and so on.
It allows the usage of the microphone to
the application through which it can record the audio or can be used for an audio
call or similar tasks.