Want to get application groups

If you mean an Application Package in /design, then you could simply drill into the application and select the "Group" filter to view all groups in it. 

If you mean something else, then you will likely need to post more details of your use case and what you're hoping to accomplish, as application packages typically aren't exposed in such a way that they can be used in a user-facing way like this.  If so, you might just need to add all the groups in your application to a "parent" group, i.e. a "APPNAME_All Groups" group.

If you mean an Application Package in /design, then you could simply drill into the application and select the "Group" filter to view all groups in it. 

If you mean something else, then you will likely need to post more details of your use case and what you're hoping to accomplish, as application packages typically aren't exposed in such a way that they can be used in a user-facing way like this.  If so, you might just need to add all the groups in your application to a "parent" group, i.e. a "APPNAME_All Groups" group.

Thanks @Mike .

I didn't mean it from Application Package in /design. 

Actually, I want to get these details to display in a report so I want to know is there any function already present that provides all groups that belong to an application? 

Any function or any plugin exists for this?

There might be a plug-in for it, but if so then I don't happen to know about it.  I still think the closest you can come to this is to create a group to be an "application parent group" to all the other groups within the application.