android - 如何解决 viewpager ：指定的孩子已经有一个父母。您必须先在孩子的父母上调用 removeView()

Question

在我的项目中，我使用 viewpager 和三个名为History, Main,的选项卡Map。主要活动包括计时器、秒表等。地图显示谷歌地图。现在进入历史，我只使用简单的 Textview。

Viewpager 流向：历史 -主要-地图

我将 Main 设置为当前项目（默认 Main 标签显示）。现在，当我从Main > Map和Map > Main滑动时，它的工作完美。但是当从Main > History滑动时没有错误，但从History返回Main ( History > Main ) eclipse 给我错误，例如：

E/AndroidRuntime(  533): java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.

仅供参考，我正在使用intent into Map Activity。请检查下面的代码。请让我知道如何解决我的问题。

ViewPager 类：

@Override
    public Fragment getItem(int position) {
        // return SwipeyTabFragment.newInstance(TITLES[position]);

        Fragment f = new Fragment();

        switch (position) {
        case 0:
            f = History.newInstance(position);
            break;
        case 1:
            f = Main.newInstance(position);
            break;
        case 2:
            f = Map.newInstance(position);
            break;

        }

        return f;

    }

历史课：

public class History extends Fragment {

public static Fragment newInstance(int position) {
    History f = new History();
    Bundle args = new Bundle();

    args.putInt("title", position);
    f.setArguments(args);
    return f;

}

 @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    ViewGroup root = (ViewGroup) inflater.inflate(R.layout.history, null);


     ( (TextView) root.findViewById(R.id.text)).setText("Hello");
    return root;
} 

}

主类：

 public class Main extends Fragment implements GPSCallback {

 ......

public static Fragment newInstance(int position) {
    Main f = new Main();
    Bundle args = new Bundle();

    args.putInt("title", position);
    f.setArguments(args);
    return f;

}

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

    final ViewGroup root = (ViewGroup) inflater
            .inflate(R.layout.main, null);

    .......

    return root;
 }

    ........
}

地图类：

public class Map extends Fragment {

private static final String KEY_STATE_BUNDLE = "localActivityManagerState";

private LocalActivityManager mLocalActivityManager;

protected LocalActivityManager getLocalActivityManager() {
    return mLocalActivityManager;
}

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

    Bundle state = null;
    if (savedInstanceState != null) {
        state = savedInstanceState.getBundle(KEY_STATE_BUNDLE);
    }

    mLocalActivityManager = new LocalActivityManager(getActivity(), true);
    mLocalActivityManager.dispatchCreate(state);
}



public static Fragment newInstance(int position) {
    Map f = new Map();
    Bundle args = new Bundle();

    args.putInt("title", position);
    f.setArguments(args);
    return f;

}


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

        Intent i = new Intent(getActivity(), MapViewActivity.class);
       // Intent i = new Intent(getActivity(), hellogooglemap.class);
        Window w = mLocalActivityManager.startActivity("tag", i); 

        View currentView=w.getDecorView(); 
        currentView.setVisibility(View.VISIBLE); 
        currentView.setFocusableInTouchMode(true); 
        ((ViewGroup) currentView).setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);
        return currentView;


      /*ViewGroup root = (ViewGroup) inflater.inflate(R.layout.history, null);


         ( (TextView) root.findViewById(R.id.text)).setText("Hello");
        return root;*/

}


 @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putBundle(KEY_STATE_BUNDLE,
                mLocalActivityManager.saveInstanceState());
    }

    @Override
    public void onResume() {
        super.onResume();
        mLocalActivityManager.dispatchResume();
    }

    @Override
    public void onPause() {
        super.onPause();
        mLocalActivityManager.dispatchPause(getActivity().isFinishing());
    }

    @Override
    public void onStop() {
        super.onStop();
        mLocalActivityManager.dispatchStop();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        mLocalActivityManager.dispatchDestroy(getActivity().isFinishing());
    }

}

日志猫：

 E/AndroidRuntime(  533): java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
 E/AndroidRuntime(  533):   at android.view.ViewGroup.addViewInner(ViewGroup.java:1976)
 E/AndroidRuntime(  533):   at android.view.ViewGroup.addView(ViewGroup.java:1871)
 E/AndroidRuntime(  533):   at android.view.ViewGroup.addView(ViewGroup.java:1828)
 E/AndroidRuntime(  533):   at android.view.ViewGroup.addView(ViewGroup.java:1808)
 E/AndroidRuntime(  533):   at android.support.v4.app.NoSaveStateFrameLayout.wrap(NoSaveStateFrameLayout.java:40)
 E/AndroidRuntime(  533):   at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:874)
 E/AndroidRuntime(  533):   at android.support.v4.app.FragmentManagerImpl.attachFragment(FragmentManager.java:1240)
 E/AndroidRuntime(  533):   at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:612)
 E/AndroidRuntime(  533):   at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1416)
 E/AndroidRuntime(  533):   at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:431)
 E/AndroidRuntime(  533):   at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:139)
 E/AndroidRuntime(  533):   at android.support.v4.view.ViewPager.populate(ViewPager.java:804)
 E/AndroidRuntime(  533):   at android.support.v4.view.ViewPager.completeScroll(ViewPager.java:1280)
 E/AndroidRuntime(  533):   at android.support.v4.view.ViewPager.computeScroll(ViewPager.java:1176)
 E/AndroidRuntime(  533):   at android.view.ViewGroup.drawChild(ViewGroup.java:1562)
 E/AndroidRuntime(  533):   at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
 E/AndroidRuntime(  533):   at android.view.ViewGroup.drawChild(ViewGroup.java:1644)
 E/AndroidRuntime(  533):   at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
 E/AndroidRuntime(  533):   at android.view.View.draw(View.java:6883)
 E/AndroidRuntime(  533):   at android.widget.FrameLayout.draw(FrameLayout.java:357)
 E/AndroidRuntime(  533):   at android.view.ViewGroup.drawChild(ViewGroup.java:1646)
 E/AndroidRuntime(  533):   at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
 E/AndroidRuntime(  533):   at android.view.ViewGroup.drawChild(ViewGroup.java:1644)
 E/AndroidRuntime(  533):   at android.view.ViewGroup.dispatchDraw(ViewGroup.java:1373)
 E/AndroidRuntime(  533):   at android.view.View.draw(View.java:6883)
 E/AndroidRuntime(  533):   at android.widget.FrameLayout.draw(FrameLayout.java:357)
 E/AndroidRuntime(  533):   at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:1862)
 E/AndroidRuntime(  533):   at android.view.ViewRoot.draw(ViewRoot.java:1522)
 E/AndroidRuntime(  533):   at android.view.ViewRoot.performTraversals(ViewRoot.java:1258)
 E/AndroidRuntime(  533):   at android.view.ViewRoot.handleMessage(ViewRoot.java:1859)
 E/AndroidRuntime(  533):   at android.os.Handler.dispatchMessage(Handler.java:99)
 E/AndroidRuntime(  533):   at android.os.Looper.loop(Looper.java:130)
 E/AndroidRuntime(  533):   at android.app.ActivityThread.main(ActivityThread.java:3683)
 E/AndroidRuntime(  533):   at java.lang.reflect.Method.invokeNative(Native Method)
 E/AndroidRuntime(  533):   at java.lang.reflect.Method.invoke(Method.java:507)
 E/AndroidRuntime(  533):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
 E/AndroidRuntime(  533):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
 E/AndroidRuntime(  533):   at dalvik.system.NativeStart.main(Native Method)
 W/ActivityManager(   68):   Force finishing activity      com.android.gps/.viewpager.SwipeyTabsSampleActivity
 W/ActivityManager(   68): Activity pause timeout for HistoryRecord{40716740 com.android.gps/.viewpager.SwipeyTabsSampleActivity}

谢谢。

编辑：

没有意图进入地图活动它可以工作 pwrfect。我的意思是当我使用与历史相同的地图时，没有任何错误。

score 41 · Accepted Answer

我使用的时候遇到了同样的问题

View res = inflater.inflate(R.layout.fragment_guide_search, container);

在 Fragment.onCreateView(...

你必须打电话

View res = inflater.inflate(R.layout.fragment_guide_search, container, false);

或者

View res = inflater.inflate(R.layout.fragment_guide_search, null);

score 27 · Accepted Answer

我也遇到过这个问题。

你可以通过添加单行来解决它mViewPager.setOffscreenPageLimit(3);

public class SwipeyTabsSampleActivity extends FragmentActivity {

...

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

    setContentView(R.layout.main);

    mViewPager = (ViewPager) findViewById(R.id.viewpager);
    mTabs = (SwipeyTabs) findViewById(R.id.swipeytabs);

    SwipeyTabsPagerAdapter adapter = new SwipeyTabsPagerAdapter(this,
            getSupportFragmentManager());
    mViewPager.setAdapter(adapter);

    mViewPager.setOffscreenPageLimit(3);  <------  Add this one
}

}

祝你好运。

score 4 · Accepted Answer

首先，RB Patel 插入代码的答案（如下所示）非常有效，但当我读到此功能时，我意识到它是一种潜在的优化，实际上并不是解决该错误的方法。

mViewPager.setOffscreenPageLimit(3);

Android 开发者网站对这种方法有以下说明：

setOffscreenPageLimit(int limit) - 设置在空闲状态下应保留到视图层次结构中当前页面任一侧的页面数。

似乎这只是对缓存在当前页面右侧或左侧的页面数量设置了限制。在我的情况下，这只是解决问题的创可贴，是的，错误停止了，一切顺利，但我的程序中仍然潜伏着糟糕的代码，根本没有被执行。我相信此方法旨在用作优化，而不是实际修复该错误。

我在尝试重载扩展 PagerAdapter 的自定义类中的 instantiateItem() 方法时遇到了这个问题。在我导航回我之前访问过/实例化的选项卡/页面后，我的错误被抛出。

我是 Android 新手，但我会尽力解释我的解决方案。引发此错误的行如下：

v.addView(child);

如果我理解正确的话，那是令人窒息的，因为孩子之前已经实例化并分配了一个父母。

当我导航回以前访问过的视图/页面时，我试图将已经具有父布局视图的视图添加到新布局，因此出现错误。

解决方案：我只是通过查看它是否设置了父视图来检查我试图显示（实例化）的子视图是否已经在其他地方实例化。如果子视图已经创建，那么我只是使用子视图的父视图而不是创建新的布局。

这是我的代码（如果冒犯了任何专家，我深表歉意）：

@Override
public Object instantiateItem(View container, int position) { 
    LinearLayout v = new LinearLayout(mContext);

    //the view being loaded (unless it already was then we have to handle it)
    View child = mViews.get(position);

    //If the child view was loaded already then it will have a parent view it belongs to
    //We return the parent view instead of adding the child to the LinearLayout we just created and returning that new layout.
    if(child.getParent() != null) {
        View parent = (View) child.getParent();
        ((ViewPager) container).addView(parent);
        return parent;
    }

    //first time instantiating a child view/page
    v.addView(child);            

    // These lines execute the first time a given page is instantiated
    ((ViewPager) container).addView(v);

    return v;
}

score 2 · Accepted Answer

// 如果要添加的子视图已经绑定到父视图，则从父视图中移除子视图，然后再次添加到容器中。

if (v.getParent() != null) {
  ((ViewGroup) v.getParent()).removeView(v);
}
container.addView(v);

score 2 · Accepted Answer

对于适配器，如果您使用的是 tabLayout 或 viewPager，而不是像下面这样getChildFragmentManager()替换它。getActivity().getSupportFragmentManager()

TabAdapter adapter = new TabAdapter(getActivity(), getActivity().getSupportFragmentManager());

score 1 · Accepted Answer

这是我的解决方案（在每个片段中使用），它允许平滑并避免内存问题：

...
private LayoutInflater mInflater;
private WeakReference<View> mRootView = null;
...

@Override
public View onCreateView(final LayoutInflater inflater, final ViewGroup container, final Bundle savedInstanceState) 
  {
  if (inflater != null)
    mInflater = inflater;
  else
    mInflater = LayoutInflater.from(getActivity());
  View rootView = mRootView == null ? null : mRootView.get();
  if (rootView != null) 
      {
      final ViewParent parent = rootView.getParent();
      if (parent != null && parent instanceof ViewGroup)
        ((ViewGroup) parent).removeView(rootView);  
      }
  else 
       {
       rootView = mInflater.inflate(R.layout.fragment_test, null, false);
       mRootView = new WeakReference<View>(rootView);
       }
  return rootView;
  }

score 1 · Accepted Answer

@Override
public Object instantiateItem(View arg0, int arg1) {
    Log.d("instantiateItem", ""+arg0+" "+arg1);
    try { 
        if(mListViews.get(arg1).getParent()==null)
            ((ViewPager) arg0).addView(mListViews.get(arg1), 0);  
        else{
            // I am new to android, it is strange that the view to be added is already bound to a parent
            // Through trials and error I solve this problem with the following codes
            // Add that the element of mlistviews is listview in pagerview;
            ((ViewGroup)mListViews.get(arg1).getParent()).removeView(mListViews.get(arg1));

            ((ViewPager) arg0).addView(mListViews.get(arg1), 0); 
        }
    } catch (Exception e) {   
        Log.d("parent=", ""+mListViews.get(arg1).getParent()); 
        e.printStackTrace();  
    }  
    return mListViews.get(arg1);
}

score 0 · Accepted Answer

如果您正在使用 FragmentPagerAdapter，那么只需在 FragmentPagerAdapter 中使用 destroyItem 方法。

@Override
public void destroyItem(ViewGroup container, int position, Object object) 
{
        FragmentTransaction ft=fm.beginTransaction();
        ft.remove((Fragment) object);
        ft.commit();
}

setOffscreenPageLimit(int limit) 消耗更多内存，在某些情况下它不能完美运行。它在任一侧的保留状态见描述。setOffscreenPageLimit(int limit) - 设置在空闲状态下应保留到视图层次结构中当前页面任一侧的页面数。

score -1 · Accepted Answer

检查您的布局文件中是否有任何 ConstrainLayout （或类似的）。这可能是引发该错误的原因。

android - 如何解决 viewpager ：指定的孩子已经有一个父母。您必须先在孩子的父母上调用 removeView()

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