2. Basic features of Android app

1, APK is the Android application installation format,. Dex is the Android binary execution file format.

2, the Android operating system is a multi-user operating system based on Linux, each application is used by different users.

3, by default, an application of a UserID, system settings, you do not need to manually set,

For such an application, the user has permission to do all of the work.

4. Each process has its own instance of a virtual machine, so each application is relatively independent.

5, by default, the application has its own Linux process, the system will decide when to close it, when the resources are not enough.

6. There are, however, exceptions.

A) You can share the same userid for two applications, allowing you to share resources with each other;

b) Applications may request access to system resources, such as contacts, text messages, etc., but need to be authorized during installation;

2. Basic features of Android app