如何使用listview实现一个简单的待办事项列表？

Question

I'm trying to implement a simple to do list using this solution Add user input into a ListView on button click , but when I implement the onCreate of the solution I get the following errors http://pastebin.com/9CBCMrjv I'm using fragments in this application and I'm wondering could this be causing the errors as maybe the constructors don't apply to fragments.

Can someone make sense of the errors or where I'm going wrong with this implementation? My understanding of the errors is that this solution can't be applied to my class as it is linked to a fragment instead of a plain activity.

This is the complete class to give you a better understanding of the problem:

    public class TopRatedFragment extends Fragment implements OnClickListener {

ListView mListView;
EditText mValue;
Button mAdd;
ArrayList<String> list = new ArrayList<String>();
ArrayAdapter<String> adapter;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.fragment_top_rated, container, false);
    return rootView;    
}

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.fragment_top_rated);

    mAdd = (Button)findViewById(R.id.newList);
    mAdd.setOnClickListener(this);
    mValue = (EditText)findViewById(R.id.listData);
    adapter = new ArrayAdapter<String>(this, android.R.layout.simple_expandable_list_item_1, list);

    // set the lv variable to your list in the xml
    mListView=(ListView)findViewById(R.id.listView);  
    mListView.setAdapter(adapter);
}
public void onClick(View v)
{
    String input = mValue.getText().toString();
    if(input.length() > 0)
    {
        // add string to the adapter, not the listview
        adapter.add(input);
        // no need to call adapter.notifyDataSetChanged(); as it is done by the adapter.add() method
    }
}   

 }

The errors

The method setContentView(int) is undefined for the type TopRatedFragment

The method findViewById(int) is undefined for the type TopRatedFragment

The method setOnClickListener(View.OnClickListener) in the type View is not applicable for the arguments (TopRatedFragment)

The method findViewById(int) is undefined for the type TopRatedFragment

The constructor ArrayAdapter<String>(TopRatedFragment, int, ArrayList<String>) is undefined

The method findViewById(int) is undefined for the type TopRatedFragment

Answer 1

setContentView(R.layout.fragment_top_rated);

wrong

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.fragment_top_rated, container, false);
     mAdd = (Button)rootView.findViewById(R.id.newList);
     mAdd.setOnClickListener(this);
     mValue = (EditText)rootView.findViewById(R.id.listData);
     adapter = new ArrayAdapter<String>(getActivity, android.R.layout.simple_expandable_list_item_1, list);

// set the lv variable to your list in the xml
     mListView=(ListView)rootView.findViewById(R.id.listView);  
     mListView.setAdapter(adapter);
    return rootView;    
}

You need to inflate a view in onCreateView and return the view

Also you use the inflated view object to initialize your views

The constructor ArrayAdapter<String>(TopRatedFragment, int, ArrayList<String>) is undefined

So change to

adapter = new ArrayAdapter<String>(getActivity(), android.R.layout.simple_expandable_list_item_1, list);

get rid of the codes in onCreate

Answer 2

I am working on the same problem. I am slowly overcoming this problem. This can help you with your TodoListAdapter problems https://gitorious.org/acal/acal/source/a6ba5fbe340ae96c1078e1e8e330e1e317ba5620:src/com/morphoss/acal/activity/TodoListAdapter.java#L70

and this with your ToDoManagerActivity problems. Crash after adding footer to ListView

I am currently enrolled in the same course you took or is taking. It is a free course and anyone can sign up. No one gets a grade for this course it is offered to increase peoples general knowledge on topics, in this case Android development. Just look on coursea.org. I feel your pain when it comes to trying to get good help and I also understand where the helper is coming from when he said he did not want to do your work for you.