You must call removeView() on the child's parent first

xiaoxiao2021-12-14 19

首先，Android中的Fragment是什么？ http://developer.android.com/guide/topics/fundamentals/fragments.html 场景：现有两个Fragment(e.g:LoginFragment、HomeFragment)需要在Android程序运行的时候进行动态加载、切换，这种情况下，比较容器出现的一个问题就是：

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

这里，贴出处理此问题的几个代码片段，备忘之：

[java] view plain copy print ? <pre>// ... @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { Log.i(TAG, "-- onCreateView(...) --"); mRootView = (View) inflater.inflate(R.layout.fragment_login, container, false); return mRootView; } // 当FragmentActivity动态切换Fragment的时候，上面代码片段中的container设置为null或者其后的参数设置为false， // 否则会报出异常： // java.lang.IllegalStateException: The specified child already has a // parent. You must call removeView() on the child's parent first. // 另外，对fragment进行remove操作前记得进行非空判断 // ... protected void goHome() { FragmentTransaction transaction = getFragmentManager().beginTransaction(); HomeFragment homeFragment = new HomeFragment(); if (null == getFragmentManager().findFragmentByTag("tag_home")) { transaction.add(R.id.fragment_main, homeFragment, "tag_home"); } if (null != getFragmentManager().findFragmentByTag("tag_login")) { transaction.remove(getFragmentManager().findFragmentByTag("tag_login")); } transaction.replace(R.id.fragment_main, homeFragment) .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE) .commit(); }</pre>main.xml<pre name="code" class="html"><?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/fragment_main" android:layout_width="fill_parent" android:layout_height="fill_parent" > </FrameLayout> </pre> <pre></pre> <h2><a id="viewpost1_TitleUrl" href="http://www.blogjava.net/easywu/archive/2010/12/11/340375.html">The specified child already has a parent. You must call removeView() on the child's parent first.的解决办法</a> </h2> 出现The specified child already has a parent. You must call removeView() on the child's parent first.这个问题，一般原因是对layout.xml的使用理解不清楚。 以xml文件方式来设计界面的布局，如果需要动态的对xml文件中的各类View进行修改的话，在代码中使用时，不能直接使用this.findViewById(R.id.***)来获取xml文件中的每个View，然后再将这些View加入到代码中的Layout中来进行显示。正确的做法应该是使用inflater。 举例如下： xml布局文件test.xml为： <div style="border-bottom:#cccccc 1px solid; border-left:#cccccc 1px solid; padding-bottom:4px; background-color:#eeeeee; padding-left:4px; width:98%; padding-right:5px; font-size:13px; word-break:break-all; border-top:#cccccc 1px solid; border-right:#cccccc 1px solid; padding-top:4px"> 1<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"><?xml version="1.0" encoding="utf-8"?> 2<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> android:orientation="vertical" android:layout_width="fill_parent" 4<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> android:layout_height="fill_parent"> 5<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> 6<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> <TextView android:id="@+id/tv1" android:layout_gravity="center_vertical" 7<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> android:layout_width="wrap_content" android:layout_height="wrap_content" 8<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> /> 9<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> 10<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> <TextView android:id="@+id/tv2" android:layout_gravity="center_vertical" 11<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> android:layout_width="wrap_content" android:layout_height="wrap_content" 12<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> /> 13<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> 14<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> <TextView android:id="@+id/tv3" 15<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> android:layout_gravity="center_vertical" android:layout_width="wrap_content" 16<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> android:layout_height="wrap_content" /> 17<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> 18<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> <ImageView android:src="@drawable/line" android:layout_width="fill_parent" 19<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> android:layout_height="fill_parent" /> 20<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> 21<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"></LinearLayout></div> 如果你需要使用这个布局XML文件，并根据自己的需要，将其中三个TextView的文字做更改，则在代码中应该这样去使用： <div style="border-bottom:#cccccc 1px solid; border-left:#cccccc 1px solid; padding-bottom:4px; background-color:#eeeeee; padding-left:4px; width:98%; padding-right:5px; font-size:13px; word-break:break-all; border-top:#cccccc 1px solid; border-right:#cccccc 1px solid; padding-top:4px"> 1<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> <img alt="" src="http://www.blogjava.net/Images/dot.gif"><img alt="" src="http://www.blogjava.net/Images/dot.gif"> 2<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> LayoutInflater inflate = (LayoutInflater) 3<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> getSystemService(Context.LAYOUT_INFLATER_SERVICE); 4<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> LinearLayout layout = (LinearLayout)inflate.inflate(R.layout.poemshowlist, null); 5<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> 6<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> ((TextView)layout.findViewById(R.id.tv1)).setText(text1); 7<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> ((TextView)layout.findViewById(R.id.tv2)).setText(text2); 8<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> ((TextView)layout.findViewById(R.id.tv3)).setText(text3); 9<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> 10<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> LinearLayout ll= new LinearLayout(this); 11<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> ll.addView(layout); 12<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> setContentView(ll); 13<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> 14<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"> <img alt="" src="http://www.blogjava.net/Images/dot.gif"><img alt="" src="http://www.blogjava.net/Images/dot.gif"> 15<img alt="" align="top" src="http://www.blogjava.net/Images/OutliningIndicators/None.gif"></div> // ... @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { Log.i(TAG, "-- onCreateView(...) --"); mRootView = (View) inflater.inflate(R.layout.fragment_login, container, false); return mRootView; } // 当FragmentActivity动态切换Fragment的时候，上面代码片段中的container设置为null或者其后的参数设置为false， // 否则会报出异常： // java.lang.IllegalStateException: The specified child already has a // parent. You must call removeView() on the child's parent first. // 另外，对fragment进行remove操作前记得进行非空判断 // ... protected void goHome() { FragmentTransaction transaction = getFragmentManager().beginTransaction(); HomeFragment homeFragment = new HomeFragment(); if (null == getFragmentManager().findFragmentByTag("tag_home")) { transaction.add(R.id.fragment_main, homeFragment, "tag_home"); } if (null != getFragmentManager().findFragmentByTag("tag_login")) { transaction.remove(getFragmentManager().findFragmentByTag("tag_login")); } transaction.replace(R.id.fragment_main, homeFragment) .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE) .commit(); }main.xml [html] view plain copy print ? <?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/fragment_main" android:layout_width="fill_parent" android:layout_height="fill_parent" > </FrameLayout> <?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/fragment_main" android:layout_width="fill_parent" android:layout_height="fill_parent" > </FrameLayout>

The specified child already has a parent. You must call removeView() on the child's parent first.的解决办法

出现The specified child already has a parent. You must call removeView() on the child's parent first.这个问题，一般原因是对layout.xml的使用理解不清楚。以xml文件方式来设计界面的布局，如果需要动态的对xml文件中的各类View进行修改的话，在代码中使用时，不能直接使用this.findViewById(R.id.***)来获取xml文件中的每个View，然后再将这些View加入到代码中的Layout中来进行显示。正确的做法应该是使用inflater。举例如下：

xml布局文件test.xml为：

1 <? xml version="1.0" encoding="utf-8" ?> 2 < LinearLayout xmlns:android ="http://schemas.android.com/apk/res/android" 3 android:orientation ="vertical" android:layout_width ="fill_parent" 4 android:layout_height ="fill_parent" > 5 6 < TextView android:id ="@+id/tv1" android:layout_gravity ="center_vertical" 7 android:layout_width ="wrap_content" android:layout_height ="wrap_content" 8 /> 9 10 < TextView android:id ="@+id/tv2" android:layout_gravity ="center_vertical" 11 android:layout_width ="wrap_content" android:layout_height ="wrap_content" 12 /> 13 14 < TextView android:id ="@+id/tv3" 15 android:layout_gravity ="center_vertical" android:layout_width ="wrap_content" 16 android:layout_height ="wrap_content" /> 17 18 < ImageView android:src ="@drawable/line" android:layout_width ="fill_parent" 19 android:layout_height ="fill_parent" /> 20 21 </ LinearLayout > 如果你需要使用这个布局XML文件，并根据自己的需要，将其中三个TextView的文字做更改，则在代码中应该这样去使用： 1 2 LayoutInflater inflate = (LayoutInflater) 3 getSystemService(Context.LAYOUT_INFLATER_SERVICE); 4 LinearLayout layout = (LinearLayout)inflate.inflate(R.layout.poemshowlist, null); 5 6 ((TextView)layout.findViewById(R.id.tv1)).setText(text1); 7 ((TextView)layout.findViewById(R.id.tv2)).setText(text2); 8 ((TextView)layout.findViewById(R.id.tv3)).setText(text3); 9 10 LinearLayout ll= new LinearLayout( this); 11 ll.addView(layout); 12 setContentView(ll); 13 14 15

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