NullPointerException addToRequestQueue(com.android.volley.Request, java.lang.String)' on a null object reference

In your AndroidManifest.xml add

<application android:name="YOURPACKAGENAME.AppController" 
             android:allowbackup="true" 
             android:icon="@drawable/ic_launcher" 
             android:label="@string/app_name"
             android:theme="@style/AppTheme">

As N1to says, you need to add your controller in the AndroidManifest.xml, if you don't add it then the onCreate() is never called and when you call AppController.getInstance() the instance is null.

<application android:name="YOURPACKAGENAME.AppController" 
         android:allowbackup="true" 
         android:icon="@drawable/ic_launcher" 
         android:label="@string/app_name"
         android:theme="@style/AppTheme">

It also works for me with:

<application android:name=".AppController" 
         android:allowbackup="true" 
         android:icon="@drawable/ic_launcher" 
         android:label="@string/app_name"
         android:theme="@style/AppTheme">

In my case, I forgot to initialize the variable rq, please, make sure you did it

    ...
    private RequestQueue rq;   // rq = null (NullPointerException if you use it)
    ...

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ...
        rq = Volley.newRequestQueue(YourActivity.this);  // rq != null
    }
    ...
    rq.add(request);