In today's world, it is a known fact that almost everyone owns a smartphone which either operates on mac, windows or android OS. Among all these, Android is most used and popular. Because it is an open source platform, it is used by any manufacturer of the phone. This highly reduces the cost of manufacturing these phones than other phones that contain their OS.
Android applications are applications that have been developed for Android platform. During the development process, each application contains many different folders and files within it, which defines and controls phones functionalities and resources. To allow the application to run in the mobile phone, there is always need to create an archive that carries all the necessities required. This archive file is what is termed as android application APK, which is the abbreviation for Android package kit.
An APK consists of the full package of all necessary files and data that are mandatory for running an application on a mobile phone. This files and data include the source code. The source code is necessary for defining the functionalities of the application and known as classes.dex. Also contained is the manifest file which specifies the permissions for the application, its flow, version code, signatures, certificates, package SHA-1 digests among others.
Lit also contains a libs file which is a directory that consists of compiled jar files or code and used as the library for applications. Another directory is assets that contain arbitrary files such as fonts, texts in it. Resources file like XML is used to define the layout of the diverse pages of the application.
Android APK support library is a collection of librarie with WhatsApp old version for Androids which can be categorized into either component or compatibility libraries. Each library applies a naming convention that is used to identify the minSdk version the project need to have to use it.
Compatibility libraries centralize on backporting characteristics from new framework releases to enable the phone operating on the previous release to take advantage of this newer APIs. It could either be v4 or v7- appcompat. The former is monolithic and larger. The latter provides the support actualization for actionbar and toolbar. It, however, needs the v4 library but does not include it.
Component libraries allow the developer to add features that are not included in the standard framework.
After thorough testing of the developed application, there is generated an export APK where the application is signed with a secret key to affirming the developer's authority over the use. After that, the signed Best app APKs is uploaded to the google store for access by its users.