Question

i am very new to android. I have a doubt regarding the OS operation in android.

In Symbian OS when an application gets crashed the device will gets switched off and will gets switched on by its own.

Where as in android when an application gets crashed it does not disturbs the other one, how does this happening, can anyone explain about this and suggest me a tutorial to learn the basics of android…..

Answer 1

From the Application Fundamentals

Once installed on a device, each Android application lives in its own security sandbox:

• The Android operating system is a multi-user Linux system in which each application is a different user.

• By default, the system assigns each application a unique Linux user ID (the ID is used only by the system and is unknown to the application). The system sets permissions for all the files in an application so that only the user ID assigned to that application can access them.

• Each process has its own virtual machine (VM), so an application’s code runs in isolation from other applications.

• By default, every application runs in its own Linux process. Android starts the process when any of the application’s components need to be executed, then shuts down the process when it’s no longer needed or when the system must recover memory for other applications.

In this way, the Android system implements the principle of least privilege. That is, each application, by default, has access only to the components that it requires to do its work and no more. This creates a very secure environment in which an application cannot access parts of the system for which it is not given permission.

To sum up:

Each app is it’s own user with it’s own ID and privileges and is running in it’s own VM isolated from other apps.

So if an app crashes, other apps need not know or care about this event since they are running in completely different virtualized context of their own and the crashed app doesn’t affect them (Unless they are sharing some resources like files which are handled by a combination of developer skill and system level exception handling).

This is how app separation is maintained in Android.