我遇到了困扰我好几天的问题。

主 Activity 中有一个 ViewPager，它包含 3 个 Fragment 作为选项卡 fragment 。在 first fragment 中有一个 ListView，其中包含一些 View ，其中最重要的是另一个 ViewPager。我想在子ViewPager中保存一些照片，并在这里使用更多的 fragment 。

现在问题来了:
当 first Fragment 停止(父 ViewPager 中的 third fragment 出现在屏幕上)并恢复时(用户切换到第二个 fragment )，应用程序崩溃并且调试器说:

java.lang.IllegalArgumentException: No view found for id 0x7f05008b (com.example.viewpager:id/sub_viewpager) for fragment ScreenSlidePageFragment

我已经使用了 getChildFragmentManager() 因为这是 nested fragments 的情况.

这里是父ViewPager中第一个fragment对应的listadapter的关键代码:

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    int type = getItemViewType(position);
    switch (type) {
        case TYPE_BANNER:
            if (convertView == null) {
                convertView = mBannerView.getBannerView(parent);
            }
            mBannerView.update(convertView);
            break;
        case TYPE_ITEM:
            break;
    }
    return convertView;
}

这里是mBannerView的代码:

public class BannerView {

    private static final DisplayImageOptions IMAGE_OPTIONS_SCALE_STRETCHED =
            new DisplayImageOptions.Builder()
                    .cacheInMemory()
                    .cacheOnDisc()
                    .imageScaleType(ImageScaleType.EXACTLY_STRETCHED)
                    .build();

    private FragmentActivity mActivity;
    private Fragment mFragment;
    private List<Banner> mBanners;
    private ScreenSlidePagerAdapter mPagerAdapter;
    private ViewPager mViewPager;

    public BannerView(FragmentActivity activity, Fragment fragment) {
        mActivity = activity;
        mFragment = fragment;
    }

    public void update(View convertView) {
        mViewPager = (ViewPager) convertView;
        if (mBanners != null && !mBanners.isEmpty()) {
            if (mPagerAdapter == null) {
                mPagerAdapter = new ScreenSlidePagerAdapter(mFragment.getChildFragmentManager());
                mViewPager.setAdapter(mPagerAdapter);
            }
        }
        mViewPager.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mOnBannerClickListener != null) {
                    mOnBannerClickListener.onBannerClick();
                }
            }
        });
    }

    class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
        public ScreenSlidePagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            return new ScreenSlidePageFragment(mBanners.get(position).getImageUrl());
        }

        @Override
        public int getCount() {
            return mBanners == null ? 0 : mBanners.size();
        }
    }

    class ScreenSlidePageFragment extends Fragment {

        private String mUrl;

        ScreenSlidePageFragment(String url) {
            super();
            mUrl = url;
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View view = inflater.inflate(R.layout.item_banner, container, false);
            if (view != null) {
                ImageView imageView = (ImageView) view.findViewById(R.id.item_banner_image);
                imageView.setLayoutParams(new LinearLayout.LayoutParams(
                        LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT));
                ImageLoader.getInstance().displayImage(mUrl, imageView, IMAGE_OPTIONS_SCALE_STRETCHED);
            }
            return view;
        }
    }
}

这里是详细的错误列表:

11-10 18:12:19.217    1444-1444/? E/MessageQueue-JNI﹕ java.lang.IllegalArgumentException: No view found for id 0x7f05008b (com.example.viewpager:id/sub_viewpager) for fragment ScreenSlidePageFragment{428d8ea0 #0 id=0x7f05008b}
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:919)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1086)
        at android.support.v4.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1884)
        at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1514)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:947)
        at android.support.v4.app.FragmentManagerImpl.attachFragment(FragmentManager.java:1280)
        at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:672)
        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
        at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:472)
        at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1068)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
        at android.support.v4.view.ViewPager$3.run(ViewPager.java:244)
        at android.support.v4.view.ViewPager.completeScroll(ViewPager.java:1761)
        at android.support.v4.view.ViewPager.onInterceptTouchEvent(ViewPager.java:1896)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1854)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2211)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1912)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2211)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1912)
        at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2211)
        at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1912)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:2228)
        at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1471)
        at android.app.Activity.dispatchTouchEvent(Activity.java:2424)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:2176)
        at android.view.View.dispatchPointerEvent(View.java:7571)
        at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:3883)
        at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3778)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
        at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3483)
        at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406)
        at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3540)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
        at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
        at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
        at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406)
        at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
        at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5419)
        at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5399)
        at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5370)
        at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5493)
        at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:182)
        at android.os.MessageQueue.nativePollOnce(Native Method)
        at android.os.MessageQueue.next(MessageQueue.java:132)
        at android.os.Looper.loop(Looper.java:124)
        at android.app.ActivityThread.main(ActivityThread.java:5289)
        at java.lang

最佳答案

更新:

我已经阅读了 FragmentManager 的源代码，终于找到了真正的原因:当 fragment 想要在 viewpager 附加到其父级之前附加到 viewpager 时，就会发生此异常。换句话说，在 getView() 方法返回之前， fragment 被膨胀了。然后调用 ViewPager 的容器的 findViewById() 方法，但 ViewPager 还处于分离状态，所以找到 null 并抛出 IllegalArgumentException。

解决办法是创建一个自定义的ViewPager并懒惰地设置适配器:

public class BannerViewPager extends ViewPager {
    PagerAdapter mPagerAdapter;

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        if (mPagerAdapter != null) {
            super.setAdapter(mPagerAdapter);
            mPageIndicator.setViewPager(this);
        }
    }

    @Override
    public void setAdapter(PagerAdapter adapter) {
    }

    public void storeAdapter(PagerAdapter pagerAdapter) {
        mPagerAdapter = pagerAdapter;
    }

    public BannerViewPager(Context context) {
        super(context);
    }

    public BannerViewPager(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

}

并且在 getView() 方法中，使用 storeAdapter() 代替 setAdapter。

以下说法不正确。以上是实际原因。

我终于得到了答案。它由两部分组成。

1. 在父 ViewPager 中，我使用 FragmentPagerAdapter 来保存 fragment ，但现在我使用 FragmentStatePagerAdapter 代替。这两者之间的区别可以在这里找到:Difference between FragmentPagerAdapter and FragmentStatePagerAdapter .
   简单来说，FragmentPagerAdapter 会在一个 Fragment 停止的时候存储更多的信息。在这种情况下，父 ViewPager 中的第一个 Fragment 被停止但不被销毁，而该 Fragment 中的 View 被销毁。恢复后， fragment 尝试重新膨胀所有 View 。但是在调用 getView() 方法并重新创建 sub-ViewPager 之前，子 FragmentManager 会尝试找到 sub-ViewPager 来保存那些先前存储的 fragment 。因此出现“java.lang.IllegalArgumentException: No view found for id”。

2. 我把FragmentPagerAdapter换成FragmentStatePagerAdapter后，又出现了一个问题。当父 fragment (父 View 分页器中的第一个 fragment )停止、销毁和恢复时， subview 分页器丢失。这发生在选择第一个 fragment 时，然后很快选择第三个 fragment ，最后重新选择第一个 fragment 。
   我认为这是android sdk的一个错误。灵感来自 here和 here ，我使用一些棘手的方法来解决问题。关键是，当一个父 fragment 被销毁时，字段成员 --- mChildFragmentManager “以一个损坏的内部状态结束”并且没有完全清理。父fragment重新创建时，mChildFragmentManager不为null，但父fragment销毁后子fragment已经被销毁，由mChildFragmentManager管理。因此，子 ViewPager 在屏幕上显示一个空 View ，它响应一个实际上不存在的假 fragment 。有趣的是，在子ViewPager上向右滑动几次后，子 fragment 和 View 又出现了。

代码如下:

父适配器:

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    if (convertView == null) {
        convertView = getBannerView(mParent);
    }
    mViewPager = (ViewPager) convertView;
    if (mBanners != null && !mBanners.isEmpty()) {
        if (mPagerAdapter == null) {
            FragmentManager childFM = mFragment.getChildFragmentManager();
            removeOldFragment(childFM);
            mPagerAdapter = new ScreenSlidePagerAdapter(childFM, mBanners);
            mViewPager.setAdapter(mPagerAdapter);
        }
    }
    return convertView;
}

关键方法:

    private void removeOldFragment(FragmentManager fm) {
        try {
            Field added = fm.getClass().getDeclaredField("mAdded");
            added.setAccessible(true);
            added.set(fm, null);
        } catch (NoSuchFieldException e) {
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }
        try {
            Field active = fm.getClass().getDeclaredField("mActive");
            active.setAccessible(true);
            active.set(fm, null);
        } catch (NoSuchFieldException e) {
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }
    }

关于android - IllegalArgumentException : No view found for id for fragment --- ViewPager in ViewPager，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19888539/