如何添加使用嵌套片段（安卓4.2）一个ViewPager内片段(How to add a Fragm

我有一个ViewPager有三个Fragments ，每一个显示List （或Grid ）。

在新Android API level 17 （果冻豆4.2），的特征之一是嵌套片段。新功能介绍说：

如果你使用ViewPager创建轻扫左，右和消耗了大部分的屏幕空间的片段，你现在可以插入片段到每个片段页。

所以，如果我理解正确的，现在我可以创造一个ViewPager与Fragments （里面例如按钮）内，当用户按下按钮显示的另一个Fragment ，而不松ViewPager使用这一新功能。

我已经花费了我早上想实现这一几种不同的方式，但我不能得到它的工作...有人可以添加如何实现一个简单的例子？

PS：我只是在这样做有兴趣，有getChildFragmentManager学习如何工作的。

Answer 1:

假设你已经创建了正确的XML布局。现在是很简单的由另一个片段主办的ViewPager显示片段。

以下是显示子片段父片段：

class ParentViewPagerFragment : Fragment() {

  override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
    val root = inflater.inflate(R.layout.fragment_parent_viewpager, container, false)

    val viewPager = root.findViewById(R.id.viewPager) as ViewPager
    // Important: Must use the child FragmentManager or you will see side effects.
    viewPager.adapter = MyAdapter(childFragmentManager)

    val tabStrip = root.findViewById<TabLayout>(R.id.pagerTabStrip)
    tabStrip.setupWithViewPager(viewPager)

    return root
  }

  class MyAdapter internal constructor(fm: FragmentManager) : FragmentPagerAdapter(fm) {

    override fun getCount(): Int = 4

    override fun getItem(position: Int): Fragment {
      val args = Bundle().apply { putInt(ChildFragment.POSITION_KEY, position) }
      return ChildFragment.newInstance(args)
    }

    override fun getPageTitle(position: Int): CharSequence = "Tab $position"
  }

  companion object {
    val TAG: String = ParentViewPagerFragment::class.java.name
  }
}

实例化FragmentPagerAdapter时使用Fragment.getChildFragmentManager（）是非常重要的。另外请注意，你不能对孩子片段使用Fragment.setRetainInstance（），否则你会得到一个异常。在进口量不再赘述。

：源代码可以在这里找到 https://github.com/marcoRS/nested-fragments

Answer 2:

编辑：如果您想更换页面的所有内容在一个ViewPager你仍然可以使用嵌套的片段，但还需要一些改变。检查下面的试样（ FragmentActivity ，设置ViewPager和PagerAdapter是相同的代码前面的代码段）：

// this will act as a fragment container, representing one page in the ViewPager
public static class WrapperFragment extends Fragment implements
        ReplaceListener {

    public static WrapperFragment newInstance(int position) {
        WrapperFragment wp = new WrapperFragment();
        Bundle args = new Bundle();
        args.putInt("position", position);
        wp.setArguments(args);
        return wp;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        FrameLayout fl = new FrameLayout(getActivity());
        fl.setId(10000);
        if (getChildFragmentManager().findFragmentByTag("initialTag") == null) {
            InitialInnerFragment iif = new InitialInnerFragment();
            Bundle args = new Bundle();
            args.putInt("position", getArguments().getInt("position"));
            iif.setArguments(args);
            getChildFragmentManager().beginTransaction()
                    .add(10000, iif, "initialTag").commit();
        }
        return fl;
    }

    // required because it seems the getChildFragmentManager only "sees"
    // containers in the View of the parent Fragment.   
    @Override
    public void onReplace(Bundle args) {
        if (getChildFragmentManager().findFragmentByTag("afterTag") == null) {
            InnerFragment iif = new InnerFragment();
            iif.setArguments(args);
            getChildFragmentManager().beginTransaction()
                    .replace(10000, iif, "afterTag").addToBackStack(null)
                    .commit();
        }
    }

}

// the fragment that would initially be in the wrapper fragment
public static class InitialInnerFragment extends Fragment {

    private ReplaceListener mListener;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        mListener = (ReplaceListener) this.getParentFragment();
        LinearLayout ll = new LinearLayout(getActivity());
        Button b = new Button(getActivity());
        b.setGravity(Gravity.CENTER_HORIZONTAL);
        b.setText("Frame " + getArguments().getInt("position"));
        b.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                Bundle args = new Bundle();
                args.putInt("positionInner",
                        getArguments().getInt("position"));
                if (mListener != null) {
                    mListener.onReplace(args);
                }
            }
        });
        ll.setOrientation(LinearLayout.VERTICAL);
        ll.addView(b, new LinearLayout.LayoutParams(250,
                LinearLayout.LayoutParams.WRAP_CONTENT));
        return ll;
    }

}

public static class InnerFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        TextView tv = new TextView(getActivity());
        tv.setText("InnerFragment in the outher Fragment with position "
                + getArguments().getInt("positionInner"));
        return tv;
    }

}

public interface ReplaceListener {
    void onReplace(Bundle args);
}

在快速浏览一下它的工作原理，但我还没有测试它得多，可能会出现的问题。

有人可以显示如何做一个简单的例子？

使用嵌套片段似乎很容易，直到Commonsware配备了更精细的样品，你可以试试下面的代码：

public class NestedFragments extends FragmentActivity {

    @Override
    protected void onCreate(Bundle arg0) {
        super.onCreate(arg0);
        ViewPager vp = new ViewPager(this);
        vp.setId(5000);
        vp.setAdapter(new MyAdapter(getSupportFragmentManager()));
        setContentView(vp);
    }

    private static class MyAdapter extends FragmentPagerAdapter {

        public MyAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            return WrapperFragment.newInstance(position);
        }

        @Override
        public int getCount() {
            return 8;
        }
    }

    public static class WrapperFragment extends Fragment {

        public static WrapperFragment newInstance(int position) {
            WrapperFragment wp = new WrapperFragment();
            Bundle args = new Bundle();
            args.putInt("position", position);
            wp.setArguments(args);
            return wp;
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            LinearLayout ll = new LinearLayout(getActivity());
            FrameLayout innerFragContainer = new FrameLayout(getActivity());
            innerFragContainer.setId(1111);
            Button b = new Button(getActivity());
            b.setText("Frame " + getArguments().getInt("position"));
            b.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View v) {
                    InnerFragment innerFragment = new InnerFragment();
                    Bundle args = new Bundle();
                    args.putInt("positionInner",
                            getArguments().getInt("position"));
                    innerFragment.setArguments(args);
                    FragmentTransaction transaction = getChildFragmentManager()
                            .beginTransaction();
                    transaction.add(1111, innerFragment).commit();
                }
            });
            ll.setOrientation(LinearLayout.VERTICAL);
            ll.addView(b, new LinearLayout.LayoutParams(
                    LinearLayout.LayoutParams.MATCH_PARENT,
                    LinearLayout.LayoutParams.WRAP_CONTENT));
            ll.addView(innerFragContainer, new LinearLayout.LayoutParams(
                    LinearLayout.LayoutParams.MATCH_PARENT,
                    LinearLayout.LayoutParams.MATCH_PARENT));
            return ll;
        }

    }

    public static class InnerFragment extends Fragment {

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            TextView tv = new TextView(getActivity());
            tv.setText("InnerFragment in the outher Fragment with position "
                    + getArguments().getInt("positionInner"));
            return tv;
        }

    }

}

我是懒惰，取得了代码的一切，但我敢肯定它可以与膨胀XML的布局工作。

Answer 3:

我创建了一个ViewPager 3元和2个子元素的索引2和3，在这里我想做的事..