Cannot resolve getSystemService method in ListView adapter

Question

I am working through John Horton\'s Android Programming for Beginners, and am currently attempting to create a note-taking app. Horton has just introduced ListVie

Answer 1

Create a class variable and a Constructor for your adapter:

Context context;
public NoteAdapter(Context context){
this.context = context;
}

Then initialize the layoutinflater the following way:

LayoutInflater inflater = LayoutInflater.from(context);

Answer 2

You should pass Context to your adapter and then replace this line:

 LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

I hope this will help.

Answer 3

Try

public class NoteAdapter extends BaseAdapter {

    Context mContext = null;

    public NoteAdapter(Context context){
       mContext = context;
    }


    @Override
    public View getView(int whichItem, View view, ViewGroup viewGroup){

        // check if view has been inflated already
        if (view == null){
            LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE); // ERROR HERE

            view = inflater.inflate(R.layout.listitem, viewGroup, false);

        }

        return view;
    }

}

Answer 4

The best way to get a LayoutInflater is by calling getLayoutInflater() on an Activity. That way, the activity's theme is taken into account. If NoteAdapter is defined inside of an Activity, just call getLayoutInflater(). If NoteAdapter is defined in its own separate Java class file, pass in a LayoutInflater via the constructor.

To more directly address your question, any View, like ListView, can call getContext() to get a Context. That is where getSystemService() is defined. So, replacing getSystemService() with viewGroup.getContext().getSystemService() would work.

Answer 5

First make the constructor of Adapter: like follow :

Context context;
public NoteAdapter(Context context)
{
  this.context = context
}    

Now use this context:

LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

Answer 6

In my views, if you are learning then learn RecyclerView. bcz it is better than ListView. i am not saying that ListView has been depricated. But there alot of internal things in which RecyclerView is better.

Following is example of Adapter

public class NoteAdapter extends BaseAdapter {

    List<Note> mNoteList = new ArrayList<Note>();

    Context context;

    public NoteAdapter(Context context){
        this.context = context;
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 

    }

    @Override
    public int getCount(){
        return mNoteList.size();
    }

    @Override
    public Note getItem(int whichItem){
        return mNoteList.get(whichItem);
    }

    @Override
    public long getItemId(int whichItem){
        return whichItem;
    }

    @Override
    public View getView(int whichItem, View view, ViewGroup viewGroup){

        // check if view has been inflated already 
        if (view == null){

            view = inflater.inflate(R.layout.listitem, viewGroup, false);

        }

        return view;
    }

} 

Inside MainActivity.java

NoteAdapter noteA = new NoteAdapter(MainActivity.this);

OR

NoteAdapter noteA = new NoteAdapter(getContext());

OR

NoteAdapter noteA = new NoteAdapter(getActivity);

// if in Fragment

OR

NoteAdapter noteA = new NoteAdapter(getApplicationContext);

// will work but no need to use it. bcz this is context of whole application. For an adapter you don't need context of whole application.