Getting the list of apps installed, and understanding the flags being used

Question

On Android, there is a common solution to get the list of apps using:

PackageManager pm=getPackageManager();
List<ApplicationInfo> packages=pm.getInstalledApplications(PackageManager.GET_META_DATA)

After this query, some of the ApplicationInfo objects get their field "metadata" being filled with stuff.

My question is simple:

What is the purpose of this field?

When should we use it, and do we really need it ?

Also, what is the meaning of just using 0 as the flags? will it get all of the apps?

Answer 1

What is the purpose of this field?

To give you the metadata for the component, as specified by <meta-data> elements in the manifest.

When should we use it

When you want to access the contents of the <meta-data> elements.

do we really need it ?

If you have <meta-data> elements, yes. Otherwise, no.

what is the meaning of just using 0 as the flags? will it get all of the apps?

It always gets "all of the apps". What the flags control is what data about those apps it retrieves. I assume this is to minimize the amount of data transferred over IPC in response to these calls, but that's just an educated guess.