为什么必须在清单文件中注册活动

Question

we worked for exam with our friends. I tried to explain manifest file, talking about how to do things. But I see that I did know why to register activities to androidManifest.xml. Still do not know :). Does anyone have an idea?

Answer 1

The manifest file is used by the system to know what kind of components do the application have. Without registering your Activities / Services / Receivers / Content Providers the system would have to scan and parse the whole apk every time someone wants to use a specific component to find it. This would be really slow, that's why there is the AndroidManifest.xml , which is a small file, and it can be parsed fast to find the required component.

Answer 2

Manifest file describes the following features...

1. Version Number and Version Code: This is useful, when you are uploading the application in Google play or go for upgrade the existing published apk.

2.minSdk and targetSdk: mentioned your min and max version number your application supports.

3.application tag: used to set the first activity or home activity when you launch an application from laucher.

4.activity tag: the list of all activities in the application declared as child tag in application tag for the easier navigation to activity manager.

When we switch one activity to another activity, the activity manager checks whether this activity is declared in manifest file or not. If not found throws exception.

Uses: Developer can have look at all the activities at a glance (By Manifest file)

5.Filter tags: By intent filters in activity tag, User can open any kind of application activity.

1. Uses permission and Uses features: All application resources are declared here. example: Internet connectivity is needed for your application, Uses WIFI in your application.