How to pass getContext to Java class not working?

Question

I am creating common java class for ProgressBar i getting error like below

java.lang.NullPointerException: Attempt to invoke virtual method 'void app.bridgecenterandstaffmanagament.com.bridgecenterandstaffmanagament.CommonClass.Singletonclass_obj.showProgressBar(android.content.Context)' on a null object reference
                                                                                                                           at app.bridgecenterandstaffmanagament.com.bridgecenterandstaffmanagament.Fragments.NotificationFragment.onCreateView(NotificationFragment.java:41)

Fragment

public class NotificationFragment extends Fragment {


    public NotificationFragment() {
        // Required empty public constructor
    }

    RecyclerView recyclerView;



    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment

        View v = inflater.inflate(R.layout.fragment_notification, container, false);


        recyclerView = v.findViewById(R.id.recylierview_notification);



       // Singletonclass_obj.getInstance().showProgressBar(getActivity());
        Singletonclass_obj.getInstance().showProgressBar(getContext());
       // print();

        return v;
    }


}

Java class

public class Singletonclass_obj extends Application{
    private  ProgressBar progressBar;
    private static Singletonclass_obj singletonclassobj;



    public static Singletonclass_obj getInstance() {
        return singletonclassobj;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        singletonclassobj = this;
    }

    public void showProgressBar(Context context)
    {
      //  Toast.makeText(context, "welcometoindia", Toast.LENGTH_SHORT).show();
        progressBar = new ProgressBar(context, null, android.R.attr.progressBarStyleSmall);
    }

    public void hideProgressBar()
    {
        if (progressBar !=null && progressBar.isShown())
            progressBar.setVisibility(View.INVISIBLE);
     }

}

Same codeing working fine my last Project..please help me any one.

Why not use `Singletonclass_obj.getInstance().showProgressBar(getActivity());`? — John Joe, Sep 12 '17 at 06:51
You application implementation is already a singleton, there is no need to make it again. — Iulian Popescu, Sep 12 '17 at 06:52
@ Iulian Popescu I tried not working..my last project same code wrking sir..but why not working here i donot know,,please tell me what mistake i did — demo, Sep 12 '17 at 06:57
did you add **Singletonclass_obj** in manifest file as `android:name=""` — AskNilesh, Sep 12 '17 at 06:58
@NileshRathod it's java class sir,i am not able to add in manifest file. — demo, Sep 12 '17 at 07:02
@Mariyappan than why are your **extends Application** to your **Singletonclass_obj** class — AskNilesh, Sep 12 '17 at 07:04
@NileshRathod For initialize SharedPreferences inside onCreate() ,,,I `extends Application` removed also tried not working — demo, Sep 12 '17 at 07:08

score 4 · Accepted Answer · answered Sep 12 '17 at 07:10

4

as per my above comment in question

try this add your Singletonclass_obj in to manifest file inside application tag like below code

<application
        android:name=".Singletonclass_obj"<!--add here your Singletonclass_obj class -->
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

answered Sep 12 '17 at 07:10

AskNilesh

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it's working sir,but progress bar not showing,toast message is printing. – demo Sep 12 '17 at 07:34
ProgressDialog is also showing but ProgressBar not showing.what was the problem sir. – demo Sep 12 '17 at 07:43
1

` progressBar = new ProgressBar(context, null, android.R.attr.progressBarStyleLarge); progressBar.setVisibility(View.VISIBLE);` inside singletonclass sir – demo Sep 12 '17 at 07:54
`progressBar = new ProgressBar(context, null, android.R.attr.progressBarStyleLarge); progressBar.setVisibility(View.VISIBLE);` not showing why sir – demo Sep 12 '17 at 07:57
Iulian Popescu, he told below answer it's not possible to show. – demo Sep 12 '17 at 07:59
How to achieve ProgressBar is there any way sir,because Progress Dialog Deprecated. – demo Sep 12 '17 at 08:01
@Mariyappan wait i'll update you – AskNilesh Sep 12 '17 at 08:02
1

@Mariyappan you won't be able to use the ProgressBar because you don't have a view to add in your `Singletonclass_obj` – AskNilesh Sep 12 '17 at 08:05
ok thank you sir very much sir. – demo Sep 12 '17 at 09:13
@Mariyappan most welcome happy to help you – AskNilesh Sep 12 '17 at 09:13

Iulian Popescu · Answer 2 · 2017-09-12T07:19:01.933

The problem was that you didn't initialise correctly the application class. Basically, the system doesn't know about your class and hence it is not created. You need to add the following in you <application> tag from Manifest and it will work:

android:name=".Singletonclass_obj"

and call it like this: ((Singletonclass_obj)getActivity().getApplication()).showProgressBar(getContext());

However, as I said in comments, you don't need to create the application class as a singleton because it already is. So your application class would be something like this:

public class Singletonclass_obj extends Application {
    private ProgressBar progressBar;

    @Override
    public void onCreate() {
        super.onCreate();
    }

    public void showProgressBar(Context context)
    {
//          Toast.makeText(context, "welcometoindia", Toast.LENGTH_SHORT).show();
        progressBar = new ProgressBar(context, null, android.R.attr.progressBarStyleSmall);
    }

    public void hideProgressBar()
    {
        if (progressBar !=null && progressBar.isShown())
            progressBar.setVisibility(View.INVISIBLE);
    }

}

Even if this will fix your issue regarding the NPE, you won't be able to use the ProgressBar because you don't have a view to add it (the application doesn't have a view).

Thank you sir,Toast message is printing but ProgressBar is not showing sir. — demo, Sep 12 '17 at 07:35
How to achieve ProgressBar is there any way sir,becase Progress Dialog Deprecated. — demo, Sep 12 '17 at 08:01

How to pass getContext to Java class not working?

2 Answers2