purpose Of using PackageManager in Android

What is PackageManager?

• What is the purpose of using it ?

What do the following methods describe?:

1. getPackageManager()
2. getApplicationInfo()
3. getPackageName()

Can any one give detailed description as I could not get complete information in the Android developer guide.

And also one sample program 开发者_如何学JAVAthat comprises all the methods.

The Android Package Manager serves a similar function to Linux package managers. http://en.wikipedia.org/wiki/Package_manager

From the API docs: "[It's a] Class for retrieving various kinds of information related to the application packages that are currently installed on the device."

Want to know which apps are installed? Ask the package manager. And so on.

The Android Developer page for PackageManager gives a detailed explanation.