java - 将 fragment 设置为 Activity 开始时的布局

Question

主要 Activity .java:

public class MainActivity extends AppCompatActivity  {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if (savedInstanceState == null) {
            getFragmentManager().beginTransaction()
                    .add(R.id.container, new homePage())
                    .commit();
        }
    }
}

这是我得到的错误:

Cannot resolve method add(int, etc...) on line add(R.id.container, new homePage())

基本上我创建了三个 fragment 和一个 Activity 。我的 Activity 没有布局(虽然它显然有布局页面，但它的 ID 是容器)。我想在 Activity 开始时将主页布局文件添加到容器中，但这似乎不起作用。到目前为止，我只创建了布局等，现在我正在尝试添加 Java 代码，但我不确定为什么这不起作用。

我还没有编辑任何 fragment 的 java 代码，所以它基本上是 android studio 在创建时添加的代码。

public class homePage extends Fragment {

    private OnFragmentInteractionListener mListener;
    private View view;

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

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.fragment_home_page, container, false);
        Button btnLogin = (Button) view.findViewById(R.id.login);
        btnLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                loginView();
            }
        });
        return view;
    }

    public static homePage newInstance() {
        homePage fragment = new homePage();
        Bundle args = new Bundle();
        return fragment;
    }

    public void loginView(){}

    @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);
    }
}

Answer 1

这可能是因为您的 homeFragment 从支持库 (android.support.v4.app.Fragment) 扩展了 Fragment，因此你的 MainActivity 应该使用 getSupportFragmentManager() 而不是 getFragmentManager() 它是 android.app.Fragment 的一部分.