Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)

Question

i want to ask, why my code doesnt work when running on device, but when i run on emulator android like a Genymotion, it's working perfectly..

someone said on this link like this : you cannot call methods on the Activity superclass until after super.onCreate(), except in certain situations. Please postpone your initialization of promptsView until after super.onCreate() has been called.

i still dont get it, please tell me if you have the same problems..

anyway , i'm sorry if my explanation is bad..

public class DestinationListAdapter extends ArrayAdapter<DestinationModel> {

    Context context;
    int layoutResourceId;
    List<DestinationModel> data = Collections.emptyList();

    public DestinationListAdapter(Context context, int layoutResourceId, List<DestinationModel> data) {
        super(context, layoutResourceId, data);
        this.layoutResourceId = layoutResourceId;
        this.context = context;
        this.data = data;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        View row = convertView;
        DestinationHolder holder = null;

        if(row == null)
        {
            // Predicted Error At Line Below
            LayoutInflater inflater = ((Activity)context).getLayoutInflater();
            row = inflater.inflate(layoutResourceId, parent, false);

            holder = new DestinationHolder();
            holder.destination_id = (TextView) row.findViewById(R.id.destination_id);
            holder.destination_name = (TextView) row.findViewById(R.id.destination_name);

            row.setTag(holder);
        }
        else
        {
            holder = (DestinationHolder)row.getTag();
        }

        DestinationModel weather = data.get(position);
        holder.destination_id.setText(weather.getDestination_id());
        holder.destination_name.setText(weather.getDestination_name());

        return row;
    }

Answer 1

for make sure when return back & continuing previous activity i just Added & checking for getContext()!=null

Here's an good example :

Before block

adapter = new ExampleAdapter(getContext());
adapter.setData(items);
listView.setAdapter(adapter);

And better replace for getActivity()!=null

For example:

if (getActivity()!=null){
    adapter = new ExampleAdapter(getActivity());
    adapter.setData(items);
    listView.setAdapter(adapter);
}

I think this is solved all problem which got the same error like my problems !

Answer 2

Be conscious of where in the lifecycle you are. The value of getContext() may not be available yet.

For example, in a DialogFragment, the context will not be available until onCreateDialog() is called. So don't try and create an adapter in the constructor, because the context will still be null at that point.