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

Question

I'm using AndroidHive register login and it's working fine in example project of this login-register.

But after many attempts trying it with CardViews and other widgets, this error appears on the LogCat:

java.lang.NullPointerException: Attempt to invoke virtual method 'void client.myproject.app.AppController.addToRequestQueue(com.android.volley.Request, java.lang.String)' on a null object reference
            at client.myproject.RegisterActivity.registerUser(RegisterActivity.java:185)
            at client.myproject.RegisterActivity.access$300(RegisterActivity.java:35)
            at client.myproject.RegisterActivity$1.onClick(RegisterActivity.java:81)
            at android.view.View.performClick(View.java:4780)
            at android.view.View$PerformClick.run(View.java:19866)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5254)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

While these codes works fine in a single app (just with register login).

I'm using Volley library.

Mildred

Did you add AppController to the AndroidManifest.xml? – Mild

Answer 1

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">

Datcha

It's because of AppController, which extends Application. – Datcha

Here you can read what Application is used for: developer.android.com/reference/android/app/Application.html – Datcha

I am also facing the same problem. But I am making login and registration process in the middle of app. So I can not add it in the application tag. I tried adding it to the activity tag but still the same error. Any help ? – Simferopol

WHAT A BOSS. Worked. – Stanzel

Answer 2

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">

Mild

Answer 3

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);

Harrisharrisburg

Answer 4

In menifest file add appcontroller as shown

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

Acculturation

Answer 5

Please check if you've initialized your requestQueue object as :

requestQueue = Volley.newRequestQueue(this);

Conflation

Answer 6

You didn't pass any data to the volley method, that means it get null data (empty data)..... see example:

protected Map<String, String> getParams() throws AuthFailureError {
                Map<String, String> map=new HashMap<>();
                map.put(region, regionName);
                return map;
            }

if regionName is empty it will give you NullPointerException, so regionName must have something.....

Wolpert

Answer 7

try this inside onCreate()

requestQueue=Volley.newRequestQueue(getApplicationContext());

Peale

Answer 8

I have the same error because i have mistakenly referenced the wrong xml file in onCreate method

// R.layout.activity_calender should be the same xml file of your activity (CalenderActivity)
setContentView(R.layout.activity_calender);

Whole