appcompat 和片段在一个活动中

Question

I'm adding fragments to my menu.....now one of the menufragments is a listview and i need to use both appcompatactivity and fragment class which isn't possible to extends both

The error are in the Screenshots

public class friendjava extends Fragment {

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.friends, container, false);


        final ListView list = (ListView) findViewById(R.id.listview1);

        final ArrayList<String> mylist = new ArrayList<>();
        mylist.add("wisdom");
        mylist.add("favour");
        mylist.add("faith");
        mylist.add("chisom");

        ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,mylist);

        list.setAdapter(arrayAdapter);

        list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                Toast.makeText(getApplicationContext(),mylist.get(position),Toast.LENGTH_SHORT).show();

            }
        });

    }
}

the error are in screenshot this is error screenshot

Answer 1

Try changing final ListView list = (ListView) findViewById(R.id.listview1);

into final ListView list = findViewById(R.id.listview1);

and after that run the program and check logcat

Answer 2

That is a fragment. A fragment is separate from an activity. You have to bind it to an activity. The findViewById() method needs to be tied to a view of an activity. Get the view reference to a view object first.

public class friendjava extends Fragment {

    private View view;
    private ListView list;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.friends, container, false);


        list = view.findViewById(R.id.listview1);

        final ArrayList<String> mylist = new ArrayList<>();
        mylist.add("wisdom");
        mylist.add("favour");
        mylist.add("faith");
        mylist.add("chisom");

        ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,mylist);

        list.setAdapter(arrayAdapter);

        list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                Toast.makeText(getApplicationContext(),mylist.get(position),Toast.LENGTH_SHORT).show();

            }
        });

    }

   return view;
}

Take care of how view is used and returned in the end.