关键android：target_state不再存在片段

概述我想我有同样的问题 here,但没有答案. 我有一个带有ViewPager的Activity和一个包含Fragment的FrameLayout.它看起来像这样： Activity |— ViewPager |-FragmentA |— Framelayout |— FragmentB |— FragmentC (her 我想我有同样的问题 here,但没有答案.

我有一个带有VIEwPager的Activity和一个包含Fragment的FrameLayout.它看起来像这样：

Activity   |— VIEwPager           |-FragmentA   |— Framelayout         |— FragmentB              |— FragmentC (here I called fragmentC.setTargetFragment method).

当我旋转设备时.我会收到这个错误：

E/AndroIDRuntime(10354): Caused by: java.lang.IllegalStateException: Fragment no longer exists for key androID:target_state: index 1E/AndroIDRuntime(10354):    at androID.support.v4.app.FragmentManagerImpl.getFragment(FragmentManager.java:586)E/AndroIDRuntime(10354):    at androID.support.v4.app.FragmentManagerImpl.movetoState(FragmentManager.java:885)E/AndroIDRuntime(10354):    at androID.support.v4.app.FragmentManagerImpl.movetoState(FragmentManager.java:1136)E/AndroIDRuntime(10354):    at androID.support.v4.app.FragmentManagerImpl.movetoState(FragmentManager.java:1118)E/AndroIDRuntime(10354):    at androID.support.v4.app.FragmentManagerImpl.dispatchCreate(FragmentManager.java:1922)E/AndroIDRuntime(10354):    at androID.support.v4.app.Fragment.performCreate(Fragment.java:1776)E/AndroIDRuntime(10354):    at androID.support.v4.app.FragmentManagerImpl.movetoState(FragmentManager.java:915)E/AndroIDRuntime(10354):    at androID.support.v4.app.FragmentManagerImpl.movetoState(FragmentManager.java:1136)E/AndroIDRuntime(10354):    at androID.support.v4.app.FragmentManagerImpl.movetoState(FragmentManager.java:1118)E/AndroIDRuntime(10354):    at androID.support.v4.app.FragmentManagerImpl.dispatchCreate(FragmentManager.java:1922)E/AndroIDRuntime(10354):    at androID.support.v4.app.FragmentActivity.onCreate(FragmentActivity.java:266)E/AndroIDRuntime(10354):    at com.example.androID.animationsdemo.MyActivity.onCreate(MyActivity.java:20)

如果我不调用fragmentC.setTargetFragment方法或我没有为VIEwpager设置适配器,一切正常.
这是我的代码：

活动：

public class MyActivity extends FragmentActivity{    @OverrIDe    protected voID onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentVIEw(R.layout.my_activity);        VIEwPager mVIEwPager = (VIEwPager) findVIEwByID(R.ID.pager);        TabsAdapter tabsAdapter = new TabsAdapter(this);        mVIEwPager.setAdapter(tabsAdapter);        findVIEwByID(R.ID.button).setonClickListener(new VIEw.OnClickListener() {            @OverrIDe            public voID onClick(VIEw v) {                MyFragmentB fragmentA = new MyFragmentB();                getSupportFragmentManager().beginTransaction().add(R.ID.flContainer,fragmentA,"TAG").addToBackStack("back").commit();            }        });    }    public static class TabsAdapter extends FragmentPagerAdapter {        private final Context mContext;        private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();        static final class TabInfo {            private final Class<?> clss;            private final Bundle args;            TabInfo(Class<?> _class,Bundle _args) {                clss = _class;                args = _args;            }        }        public TabsAdapter(FragmentActivity activity) {            super(activity.getSupportFragmentManager());            mContext = activity;            TabInfo tabInfo = new TabInfo(MyFragmentA.class,null);            mTabs.add(tabInfo);        }        @OverrIDe        public Fragment getItem(int position) {            TabInfo info = mTabs.get(position);            return Fragment.instantiate(mContext,info.clss.getname(),info.args);        }        @OverrIDe        public int getCount() {            return mTabs.size();        }    }}

活动布局：

<linearLayout xmlns:androID="http://schemas.androID.com/apk/res/androID"    androID:layout_wIDth="match_parent"    androID:layout_height="match_parent"    androID:orIEntation="vertical">    <button        androID:ID="@+ID/button"        androID:layout_wIDth="match_parent"        androID:layout_height="wrap_content"        androID:text="Add Fragment B"/>    <FrameLayout        androID:layout_wIDth="match_parent"        androID:layout_height="300dip"        androID:ID="@+ID/flContainer" >    <TextVIEw        androID:layout_wIDth="match_parent"        androID:layout_height="200dp"        androID:text="wrtadfa"/>    </FrameLayout>    <androID.support.v4.vIEw.VIEwPager        androID:ID="@+ID/pager"        androID:layout_below="@+ID/rlContainer"        androID:layout_wIDth="match_parent"        androID:layout_height="300dip" /></linearLayout>

和FragmentA：

public class MyFragmentA extends Fragment {    @OverrIDe    public voID onAttach(Activity activity) {        super.onAttach(activity);    }    @OverrIDe    public VIEw onCreateVIEw(LayoutInflater inflater,VIEwGroup container,Bundle savedInstanceState) {        VIEw myFragmentVIEw = inflater.inflate(R.layout.fragment_a,container,false);        return myFragmentVIEw;    }}

FragmentA布局：

<linearLayout xmlns:androID="http://schemas.androID.com/apk/res/androID"   androID:layout_wIDth="fill_parent"   androID:layout_height="fill_parent"   androID:orIEntation="vertical" >   <TextVIEw       androID:layout_wIDth="match_parent"       androID:layout_height="wrap_content"       androID:text="It's Fragment A" /></linearLayout>

片段B：

public class MyFragmentB extends Fragment implements MyFragmentC.CallBack {    @OverrIDe    public VIEw onCreateVIEw(LayoutInflater inflater,Bundle savedInstanceState) {        VIEw myFragmentVIEw = inflater.inflate(R.layout.fragment_b,false);        myFragmentVIEw.findVIEwByID(R.ID.button).setonClickListener(new VIEw.OnClickListener() {            @OverrIDe            public voID onClick(VIEw v) {                MyFragmentC fragmentA = new MyFragmentC();                //This caused the problem                fragmentA.setTargetFragment(MyFragmentB.this,0);                getChildFragmentManager().beginTransaction().add(R.ID.flContainer2,"TAG").addToBackStack("back").commit();            }        });        return myFragmentVIEw;    }}

fragment_b.xml：

<?xml version="1.0" enCoding="utf-8"?><linearLayout xmlns:androID="http://schemas.androID.com/apk/res/androID"   androID:layout_wIDth="fill_parent"   androID:layout_height="fill_parent"   androID:background="#888888"   androID:orIEntation="vertical" >   <TextVIEw       androID:layout_wIDth="match_parent"       androID:layout_height="wrap_content"       androID:text="It's Fragment B" />   <TextVIEw       androID:ID="@+ID/c_received"       androID:layout_wIDth="match_parent"       androID:layout_height="wrap_content" />    <button        androID:ID="@+ID/button"        androID:layout_wIDth="match_parent"        androID:layout_height="wrap_content"        androID:text="Add Fragment C"/>    <FrameLayout        androID:ID="@+ID/flContainer2"        androID:layout_wIDth="match_parent"        androID:layout_height="match_parent">    </FrameLayout></linearLayout>

FragmentC：

public class MyFragmentC extends Fragment {    public static interface CallBack{        //some call back    }    @OverrIDe    public voID onAttach(Activity activity) {        super.onAttach(activity);        if(getTargetFragment() != null){            CallBack callBack = (CallBack) getTargetFragment();        }    }    @OverrIDe    public VIEw onCreateVIEw(LayoutInflater inflater,Bundle savedInstanceState) {        VIEw myFragmentVIEw = inflater.inflate(R.layout.fragment_c,false);        return myFragmentVIEw;    }}

fragment_c.xml：

<linearLayout xmlns:androID="http://schemas.androID.com/apk/res/androID"   androID:layout_wIDth="fill_parent"   androID:layout_height="fill_parent"   androID:background="#888888"   androID:orIEntation="vertical" >   <TextVIEw       androID:layout_wIDth="match_parent"       androID:layout_height="wrap_content"       androID:text="It's Fragment C" /></linearLayout>

我知道我可以通过让Activity实现MyFragmentC.CallBack而不是FragmentB来实现它.
但我只是好奇为什么会发生???
如果我没有为vIEwpager设置Adapter或者不在FragmentC中调用“setTargetFragment”.一切都很好.

很抱歉,因为我不知道如何在这里很好地格式化代码,这是一个很长的帖子.任何帮助都可以欣赏.

解决方法 请查看谷歌的讨论主题,建议他们删除setTargetFragment(),而不是使用getParentFragment().更多细节在这里提供： https://code.google.com/p/android/issues/detail?id=54520 总结

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