ScrollView can host only one direct child

[danxuezx]

运行程序遇到了java.lang.RuntimeException: Unable to start activity 错误，而它是由ScrollView can host only one direct child引起的，完整错误信息如下：

07-02 23:47:19.579: E/AndroidRuntime(4294): FATAL EXCEPTION: main
07-02 23:47:19.579: E/AndroidRuntime(4294): Process: com.SnowyZhang.scandevices, PID: 4294
07-02 23:47:19.579: E/AndroidRuntime(4294): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.SnowyZhang.scandevices/com.SnowyZhang.scandevices.MainActivity}: java.lang.IllegalStateException: ScrollView can host only one direct child
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2235)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2285)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.app.ActivityThread.access$800(ActivityThread.java:138)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1236)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.os.Handler.dispatchMessage(Handler.java:102)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.os.Looper.loop(Looper.java:149)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.app.ActivityThread.main(ActivityThread.java:5061)
07-02 23:47:19.579: E/AndroidRuntime(4294): at java.lang.reflect.Method.invokeNative(Native Method)
07-02 23:47:19.579: E/AndroidRuntime(4294): at java.lang.reflect.Method.invoke(Method.java:515)
07-02 23:47:19.579: E/AndroidRuntime(4294): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
07-02 23:47:19.579: E/AndroidRuntime(4294): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:610)
07-02 23:47:19.579: E/AndroidRuntime(4294): at dalvik.system.NativeStart.main(Native Method)
07-02 23:47:19.579: E/AndroidRuntime(4294): Caused by: java.lang.IllegalStateException: ScrollView can host only one direct child
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.widget.ScrollView.addView(ScrollView.java:284)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:938)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1467)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:570)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1171)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.app.Activity.performStart(Activity.java:5397)
07-02 23:47:19.579: E/AndroidRuntime(4294): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2208)
07-02 23:47:19.579: E/AndroidRuntime(4294): ... 11 more


activity_main.xml内容如下：

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.SnowyZhang.scandevices.MainActivity"
    tools:ignore="MergeRootFrame" >
 	
	 <LinearLayout
	    android:orientation="vertical"  
	    android:layout_width="fill_parent"  
	    android:layout_height="wrap_content"  
	    >  
	<Button  
	    android:id="@+id/scan"  
	    android:layout_width="wrap_content"   
	    android:layout_height="wrap_content"   
	    android:text="@string/ScanWifi"  
	    />  
	<Button  
	    android:id="@+id/start"  
	    android:layout_width="wrap_content"   
	    android:layout_height="wrap_content"   
	    android:text="@string/OpenWifi"  
	    />  
	<Button  
	    android:id="@+id/stop"  
	    android:layout_width="wrap_content"   
	    android:layout_height="wrap_content"   
	    android:text="@string/CloseWifi"  
	    />  
	<Button  
	    android:id="@+id/check"  
	    android:layout_width="wrap_content"   
	    android:layout_height="wrap_content"   
	    android:text="@string/WifiStatus"  
	    />  
	  <TextView  
	    android:id="@+id/allNetWork"  
	    android:layout_width="fill_parent"  
	    android:layout_height="wrap_content"   
	    android:text="@string/NoWifi"  
	    />  
	    </LinearLayout> 
    
</ScrollView>

[danxuezx]

为什么将android:id="@+id/container"从ScrollView里移到LinearLayout就ok了？

引用 1 楼 hjywyj 的回复:

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.SnowyZhang.scandevices.MainActivity"
    tools:ignore="MergeRootFrame" >
      
     <LinearLayout
        android:id="@+id/container"
        android:orientation="vertical"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        >  
    <Button  
        android:id="@+id/scan"  
        android:layout_width="wrap_content"   
        android:layout_height="wrap_content"   
        android:text="@string/ScanWifi"  
        />  
    <Button  
        android:id="@+id/start"  
        android:layout_width="wrap_content"   
        android:layout_height="wrap_content"   
        android:text="@string/OpenWifi"  
        />  
    <Button  
        android:id="@+id/stop"  
        android:layout_width="wrap_content"   
        android:layout_height="wrap_content"   
        android:text="@string/CloseWifi"  
        />  
    <Button  
        android:id="@+id/check"  
        android:layout_width="wrap_content"   
        android:layout_height="wrap_content"   
        android:text="@string/WifiStatus"  
        />  
      <TextView  
        android:id="@+id/allNetWork"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"   
        android:text="@string/NoWifi"  
        />  
        </LinearLayout> 
     
</ScrollView>

[骑着蜗牛去爬山]

<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.SnowyZhang.scandevices.MainActivity"
    tools:ignore="MergeRootFrame" >
      
     <LinearLayout
        android:id="@+id/container"
        android:orientation="vertical"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        >  
    <Button  
        android:id="@+id/scan"  
        android:layout_width="wrap_content"   
        android:layout_height="wrap_content"   
        android:text="@string/ScanWifi"  
        />  
    <Button  
        android:id="@+id/start"  
        android:layout_width="wrap_content"   
        android:layout_height="wrap_content"   
        android:text="@string/OpenWifi"  
        />  
    <Button  
        android:id="@+id/stop"  
        android:layout_width="wrap_content"   
        android:layout_height="wrap_content"   
        android:text="@string/CloseWifi"  
        />  
    <Button  
        android:id="@+id/check"  
        android:layout_width="wrap_content"   
        android:layout_height="wrap_content"   
        android:text="@string/WifiStatus"  
        />  
      <TextView  
        android:id="@+id/allNetWork"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"   
        android:text="@string/NoWifi"  
        />  
        </LinearLayout> 
     
</ScrollView>

[网络咖啡]

ScrollView下面只能包含一个子布局