purpose Of using PackageManager in Android

Question

What is Package Manager ? What is the purpose of using it ? What does the following methods describe:
(1) getPackageManager()
(2) getApplicationInfo()
(3) getPackageName()

Can any one give detailed description as I could not get complete inf. in Android developer guide.
And also one sample program that comprises all the methods.

thanks in Advance

Answer 1

Here is the detailed explanation.

Answer 2

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.