如何在 Fragment 中设置 ViewPager

Question

我需要在片段中放置一个 ViewPager，但我有两个片段，片段 1 是我的 MENU，片段 2 我想用作 ViewPagerIndicator。

但是一个片段不能有另一个片段……我需要为此做什么？

Answer 1

从 Android 4.2 开始，有嵌套片段。http://developer.android.com/about/versions/android-4.2.html#NestedFragments 支持库现在还包括对旧 Android 版本的支持。

所以你可以这样做：

@Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    ViewPager mViewPager = (ViewPager) view.findViewById(R.id.viewPager);
    mViewPager.setAdapter(new MyAdapter(getChildFragmentManager()));
    }

此处提供完整实现：​​https://github.com/marcoRS/nested-fragments/tree/master/src/com/burnside/digital/nestedfragments

Answer 2

您必须使用getChildFragmentManager() 而不是getSupportFragmentManager() 才能在片段中获取FragmentManger。 但是你不应该使用FragmentStatePagerAdapter 而不是FragmentPagerAdapter。

Answer 3

只需在 Fragments 中使用 getChildFragmentManager() 而不是 getSupportFragmentManager()。

内部片段

new ViewPagerAdapter(getChildFragmentManager());

内部活动

new ViewPagerAdapter(getSupportFragmentManager());

简单代码

fragment_sample.xml布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <com.google.android.material.tabs.TabLayout
        android:id="@+id/tablayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <androidx.viewpager.widget.ViewPager
        android:id="@+id/viewpager"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1" />

</LinearLayout>

SampleFragment.java类

public class SampleFragment extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View fragmentView = inflater.inflate(R.layout.fragment_sample, container, false);
        return fragmentView;
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        // find views by id
        ViewPager viewPager = view.findViewById(R.id.viewpager);
        TabLayout tabLayout = view.findViewById(R.id.tablayout);

        // attach tablayout with viewpager
        tabLayout.setupWithViewPager(viewPager);

        ViewPagerAdapter adapter = new ViewPagerAdapter(getChildFragmentManager());

        // add your fragments
        adapter.addFrag(new SampleFragment(), "Tab1");
        adapter.addFrag(new SampleFragment2(), "Tab2");
        adapter.addFrag(new SampleFragment3(), "Tab3");

        // set adapter on viewpager
        viewPager.setAdapter(adapter);
    }
}

ViewPagerAdapter.java类

// common adapter for all view pager in your project.
public class ViewPagerAdapter extends FragmentStatePagerAdapter {
    private final List<Fragment> mFragmentList = new ArrayList<>();
    private final List<String> mFragmentTitleList = new ArrayList<>();

    public ViewPagerAdapter(FragmentManager manager) {
        super(manager);
    }

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

    @Override
    public int getCount() {
        return mFragmentList.size();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitleList.get(position);
    }

    public void addFrag(Fragment fragment) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add("");
    }

    public void addFrag(Fragment fragment, String title) {
        mFragmentList.add(fragment);
        mFragmentTitleList.add(title);
    }
}

重要的相关链接

• Difference between getSupportFragmentManager() and getChildFragmentManager()?
• getSupportFragmentManager() versus getFragmentManager() in android 3.0+
• Difference between FragmentPagerAdapter and FragmentStatePagerAdapter

Answer 4

这是可能的。尝试执行此代码 view_pager_fragment.xml 文件

<android.support.design.widget.AppBarLayout
    android:id="@+id/appBarLayout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

    <android.support.design.widget.TabLayout
        android:id="@+id/tab"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</android.support.design.widget.AppBarLayout>

<android.support.v4.view.ViewPager
    android:id="@+id/viewpager"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior" />

ViewPagerFragment

ViewPager viewPager;
TabLayout tabLayout;

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.tracks, container, false);

    viewPager = (ViewPager) view.findViewById(R.id.viewpager);
    tabLayout = (TabLayout) view.findViewById(R.id.tab);

    return view;
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    setupViewPager(viewPager);
    tabLayout.setupWithViewPager(viewPager);

    tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
        @Override
        public void onTabSelected(TabLayout.Tab tab) {

        }

        @Override
        public void onTabUnselected(TabLayout.Tab tab) {

        }

        @Override
        public void onTabReselected(TabLayout.Tab tab) {

        }
    });
}

private void setupViewPager(ViewPager viewPager) {
    ViewPagerAdapter viewPagerAdapter = new ViewPagerAdapter(getChildFragmentManager());``

  

    viewPager.setAdapter(viewPagerAdapter);
}

private class ViewPagerAdapter extends FragmentPagerAdapter {

    public ViewPagerAdapter(FragmentManager fragmentManager) {
        super(fragmentManager);
    }

    @Override
    public Fragment getItem(int position) {
        if(position == 0) return new FirstFragment();
        if(position == 1) return new SecoundFragment();
        if(position == 2) return new LoginFragment();
        throw new IllegalStateException("Position is unexpectedly " + position);
    }

    @Override
    public int getCount() {
        return 3;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        if(position == 0) return "First";
        if(position == 1) return "Secound";
        if(position == 2) return "Login";
        throw new IllegalStateException("Position is unexpectedly " + position);
    }
}

Answer 5

借助 Android Support V4 库，您可以在另一个片段中添加一个片段。尝试使用它，它可能会解决您的问题。

Answer 6

在阅读了一些示例之后，您不能在 FragmentActivity 中包含 FragmentActivity。 不需要有两个片段，这需要一个 FragmentPageAdapter ......我只需要这样做。

<android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="0px"
        android:layout_weight="1" >
</android.support.v4.view.ViewPager>

<LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0"
        android:gravity="center"
        android:measureWithLargestChild="true"
        android:orientation="horizontal" >

<Button
            android:id="@+id/first"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="First" >
        </Button>

<Button
            android:id="@+id/last"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Last" >
</Button>
</LinearLayout>

来源： http://www.truiton.com/2013/05/android-fragmentpageradapter-example/