android - 添加 fragment 时无法解决

Question

正在关注 this guide我正在尝试设置 fragment ，但这里出现错误:

getSupportFragmentManager().beginTransaction()
    .add(R.id.fragment_container, myfrag).commit();

Can't resolve method add(int, com.mypackage.MyFragment)

我有一个带有 fragment_container id 和 MyFragment Extends Fragment 的 FrameLayout...所以我不确定我在这里做错了什么...第一次使用 fragment ...

这是我的代码

主要 Activity :

public class MainFragmentActivity extends FragmentActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.settings_fragmentactivity);
        int frag = getIntent().getExtras().getInt("fragment");

        if(findViewById(R.id.fragment_container) != null) {
            if(savedInstanceState != null) return;

            MyFragment myfrag= new MyFragment();
                        getSupportFragmentManager().beginTransaction().add(R.id.fragment_container, myfrag).commit();

...

我的 fragment :

public class MyFragment extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.settings_devicelist, container, false);
    }

    @Override
    public void onCreate(Bundle savedState) {
        super.onCreate(savedState);

        listView = (ListView)getView().findViewById(R.id.lvHosts);
...

settings_framentactivity.xml:

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/fragment_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

Answer 1

确保您正在导入 android.support.v4.app.Fragment 类而不是 android.app.Fragment