Question

当我点击＆＃34;新项目＆＃34;中的按钮时，我正在尝试保存一些信息。页。之后，我想将这些信息保存在＆＃34; Projects＆＃34;页面并显示在＆＃34;我的项目＆＃34;页。出于某种原因，它没有显示任何内容。请帮帮忙？

新项目页面：

public class NewProjectFragment extends Fragment {
    // TODO: Rename parameter arguments, choose names that match
    // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";

    // TODO: Rename and change types of parameters
    private String mParam1;
    private String mParam2;

    LinearLayout container;

    TextView new_project;
    String tv_project_name;

    private OnFragmentInteractionListener mListener;

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

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment NewProjectFragment.
     */
    // TODO: Rename and change types and number of parameters
    public static NewProjectFragment newInstance(String param1, String param2) {
        NewProjectFragment fragment = new NewProjectFragment();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }



    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }


    }

    Button addButton;

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

        View view = inflater.inflate(R.layout.fragment_new_project, container, false);

       new_project=(TextView) view.findViewById(R.id.textView_new_project);

       tv_project_name= (String) new_project.getText();

        addButton= (Button) view.findViewById(R.id.button_add_project);

        addButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v)
            {
                addItem(tv_project_name);
            }
        });

        return view;
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnFragmentInteractionListener) {
            mListener = (OnFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    /**
     * This interface must be implemented by activities that contain this
     * fragment to allow an interaction in this fragment to be communicated
     * to the activity and potentially other fragments contained in that
     * activity.
     * <p>
     * See the Android Training lesson <a href=
     * "http://developer.android.com/training/basics/fragments/communicating.html"
     * >Communicating with Other Fragments</a> for more information.
     */
    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);
    }

    public void addItem(String name) {
        Projects project=new Projects();
        project.addItem(tv_project_name);
    }

}

我的项目页面：

public class MyProjectsFragment extends Fragment {
    // TODO: Rename parameter arguments, choose names that match
    // the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
    private static final String ARG_PARAM1 = "param1";
    private static final String ARG_PARAM2 = "param2";

    // TODO: Rename and change types of parameters
    private String mParam1;
    private String mParam2;

    private OnFragmentInteractionListener mListener;

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

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment MyProjectsFragment.
     */
    // TODO: Rename and change types and number of parameters
    public static MyProjectsFragment newInstance(String param1, String param2) {
        MyProjectsFragment fragment = new MyProjectsFragment();
        Bundle args = new Bundle();
        args.putString(ARG_PARAM1, param1);
        args.putString(ARG_PARAM2, param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_PARAM1);
            mParam2 = getArguments().getString(ARG_PARAM2);
        }
    }


    ListView listView;
    ArrayList<String> listItems= Projects.getArrayList();
    ArrayAdapter<String> adapter;

    @Override
    public void onStart() {
        super.onStart();
        adapter= new ArrayAdapter<String>(getActivity(), android.R.layout.simple_list_item_1, listItems);
        listView.setAdapter(adapter);
        Create();
    }

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

        View view = inflater.inflate(R.layout.fragment_my_projects, container, false);

        listView=(ListView) view.findViewById(R.id.listview_projects);
        listItems= new ArrayList<String>();

        return view;
    }

    // TODO: Rename method, update argument and hook method into UI event
    public void onButtonPressed(Uri uri) {
        if (mListener != null) {
            mListener.onFragmentInteraction(uri);
        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnFragmentInteractionListener) {
            mListener = (OnFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement OnFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    /**
     * This interface must be implemented by activities that contain this
     * fragment to allow an interaction in this fragment to be communicated
     * to the activity and potentially other fragments contained in that
     * activity.
     * <p>
     * See the Android Training lesson <a href=
     * "http://developer.android.com/training/basics/fragments/communicating.html"
     * >Communicating with Other Fragments</a> for more information.
     */
    public interface OnFragmentInteractionListener {
        // TODO: Update argument type and name
        void onFragmentInteraction(Uri uri);
    }

    public void Create() {


       /* listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> a, View v, int position,
                                    long id) {
            }
        });*/

    }
}

项目类：

public class Projects {

    static ArrayList<String> names= new ArrayList<String>();

    public void addItem(String name)
    {
        names.add(name);
    }

    public static ArrayList getArrayList()
    {
        return names;
    }
}

Answer 1

每次您输入My Project时，您都会在listItems= new ArrayList<String>()中onCreateView。它没有明确的数据。

每当你addItem时，你会初始化一个新的Project，这很奇怪。我的建议是：

public class Projects {

    static ArrayList<String> names= new ArrayList<String>();

    public static void addItem(String name)
    {
        names.add(name);
    }

    public static ArrayList getArrayList()
    {
        return names;
    }
}

Project.getArrayList()到getList

Project.addItem("")添加数据

这种方式还不是很合适，但应该可行。

ListView不显示信息

1 个答案: