再次重新加载时，ViewPager Fragment消失

Question

以下是布局

的test.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:orientation="vertical"
          android:layout_width="match_parent"
          android:layout_height="match_parent">

<Button android:layout_width="wrap_content" android:layout_height="wrap_content"
        android:text="Click"
        android:id="@+id/button"
        />

<!-- Framelayout to display Fragments -->
<FrameLayout
        android:id="@+id/frame_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

test_detail.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:orientation="vertical"
          android:layout_width="match_parent"
          android:layout_height="match_parent">

<TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Hello"
        android:id="@+id/textView" android:layout_gravity="center_horizontal"/>
</LinearLayout>

common_view_pager_layout

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:orientation="vertical"
          android:layout_width="match_parent"
          android:layout_height="match_parent">

    <android.support.v4.view.ViewPager
        android:id="@+id/MainViewerPage"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        >
    <android.support.v4.view.PagerTabStrip
            android:id="@+id/TitlePageTabStrip"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </android.support.v4.view.ViewPager>

</LinearLayout>

以下是我的活动代码

    public class TestFragmentActivity extends FragmentActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    this.setContentView(R.layout.test);

    Button button = (Button) this.findViewById(R.id.button);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            FragmentManager fragmentManager = getSupportFragmentManager();
            fragmentManager.beginTransaction()
                    .replace(R.id.frame_container, new HomeFragment()).commit();

        }
    });

    }

    public class HomeFragment extends Fragment {
    private PagerAdapter _adapter;

    public HomeFragment() {
    }

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

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

        this._adapter = new PagerAdapter(TestFragmentActivity.this);
        this._adapter.add(new DetailFragment());

        ViewPager pager = (ViewPager) view.findViewById(R.id.MainViewerPage);
        pager.setAdapter(this._adapter);

        return view;
    }
    }


    public class DetailFragment extends Fragment {

    public DetailFragment() {
    }

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

        View rootView = inflater.inflate(R.layout.test_detail, container, false);

        return rootView;
    }
    }


    public class PagerAdapter extends FragmentPagerAdapter {
    private ArrayList<Fragment> _fragments;

    public PagerAdapter(FragmentActivity activity) {
        super(activity.getSupportFragmentManager());

        this._fragments = new ArrayList<Fragment>();
    }

    public void add(Fragment fragment) {
        this._fragments.add(fragment);
    }

    @Override
    public Fragment getItem(int position) {
        return this._fragments.get(position);
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return "Test";
    }

    @Override
    public int getCount() {
        return 1;
    }


    }
}

单击按钮时，将显示ViewPager中的片段

但是当我再次点击按钮时，片段消失了

请帮帮我。

Answer 1

尝试使用：

适配器的构造函数中的

更改为：

public class MyPagerAdapter extends FragmentPagerAdapter {
private ArrayList<Fragment> _fragments;

public MyPagerAdapter(FragmentManager activity) {
    super(activity);

    this._fragments = new ArrayList<Fragment>();
}

public void add(Fragment fragment) {
    this._fragments.add(fragment);
}

@Override
public Fragment getItem(int position) {
    return this._fragments.get(position);
}

@Override
public CharSequence getPageTitle(int position) {
    return "Test";
}

@Override
public int getCount() {
    return 1;
}


}

当你想创建适配器时，将getChildFragmentManager（）发送到它的构造函数

public class HomeFragment extends Fragment {
private MyPagerAdapter _adapter;

public HomeFragment() {
}


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

    View view = inflater.inflate(R.layout.common_view_pager_layout, container, false);
    ViewPager pager = (ViewPager) view.findViewById(R.id.MainViewerPage);

    this._adapter = new MyPagerAdapter(getChildFragmentManager());
    this._adapter.add(new DetailFragment());


    pager.setAdapter(this._adapter);


    return view;
}
}

我测试它并且它有效，任何问题都会对它进行评论。

祝你好运！

Answer 2

尝试在代码中添加以下行：

public int getItemPosition(Object object) {
   return POSITION_NONE;
}

并添加以下行

pager.setOnPageChangeListener(new OnPageChangeListener() {
     @Override
     public void onPageSelected(int position) {
          ... anything you may need to do to handle pager state ...
          adapter.notifyDataSetChanged(); //this line will force all pages to be loaded fresh when changing between fragments
     }

在

pager.setAdapter(adapter);

希望这可以帮到你！

Answer 3

在你的Fragment类中，在onCreate（）方法中，你必须像这样调用setRetainInstance（true）：

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);     
    setRetainInstance(true);
}

这告诉FragmentManager让你的片段重新加载。 另外，检查您的清单文件是否有任何

android:screenOrientation

配置更改，您基本上会说由于配置更改而自行处理重新加载。

Answer 4

在PagerFragment的onResume（）中添加以下内容：

@Override
public void onResume() {
    super.onResume();

    for (Fragment fragment : getFragmentManager().getFragments()) {
        if (fragment instanceof Tab1Fragment || fragment instanceof Tab2Fragment) {
            FragmentTransaction ft = getFragmentManager().beginTransaction();
            ft.detach(fragment);
            ft.attach(fragment);
            ft.commit();
        }
    }
}

Answer 5

确保将适配器实例传递给子片段管理器，而不是片段管理器。

像这样：

this._adapter = new PagerAdapter(getChildFragmentManager());