Questions about google map

google map display problem

 
/ / Initialize the map component, set the satellite map showing the main road, and there is the zoom control 
SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager () findFragmentById (R.id.map);. 
gmap = fm.getMap (); 
gmap.setMapType (GoogleMap.MAP_TYPE_HYBRID); 
gmap.getUiSettings () setZoomControlsEnabled (true);. 

This code is to get off the above map google services framework with a piece of code that I have installed on the phone on google services and google play, official maps google are already used, play store can be run properly. However, I run this code, the above gmap = fm.getMap () when the phrase, gmap is always a null value, it has been reported that a null pointer exception error. I still see the following exceptions are Google Play Store signature invalid.
Which big wooden God can help facie What is the problem? (I always suspected the problem is the phone, do not know is not)<-! Main posts under Banner (D4) -><-! Posts under the main text (D5) ->
Reply:
Use google map need to apply for a key,

Google Play Store signature invalid. This is a signature error. Determine your application generates?


SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager () findFragmentById (R.id.map);.
gmap = fm.getMap ();
This usage requires version 4.0 can be used.


Reply:
Misspoke should be version 3.0
Reply:

cited a floor birdsaction reply:

use google map need to apply for a key,

Google Play Store signature invalid. This is a signature error. Determine your application generates?


SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager () findFragmentById (R.id.map);.
gmap = fm.getMap ();
This usage requires version 4.0 can be used.

It seems that my phone version is really a problem, I still use 2.3.
The null pointer exception is SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager () findFragmentById (R.id.map);. These words lead to?
Reply:
Should you try to use 3.1, API said above is version 12 can be used.