android - 水平滑动菜单调用Activity，恢复后导致NullPointerException

Question

我的 ActivityA 有一个包含一个按钮的水平滑动菜单。这是行为：

1）在onClick期间，它会通过startActivityForResult()调用ActivityB，供用户选择类别组。

2）然后，它会调用另一个活动，ActivityC，供用户选择一个子类别。

3）之后，它将返回到ActivityA。（ActivityB 和 ActivityC 都在完成后调用 finish()。）

在恢复到 ActivityA 后，应用程序崩溃了，这是我在 Logcat 中看到的。他们都没有指向我的代码。请问有什么建议吗？

** 而且，我刚刚发现 NullPointer 发生在 CustomHorizontalScrollView.onLayout() 是因为滚动菜单在恢复后失去焦点吗？或者，它与应该显示哪个 TargetFragment 混淆了？我尝试在 onLayout() 中为 NullPointer 放入 try-catch，这样我的应用程序就不会 FC。滚动菜单和主布局显示得很好。但只有搜索结果没有显示。

活动一：源代码

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    LayoutInflater inflater = LayoutInflater.from(this);
    scrollView = (CustomHorizontalScrollView) inflater.inflate(R.layout.slide_menu, null);
    setContentView(scrollView);

    menu = inflater.inflate(R.layout.horz_scroll_menu, null);
    app = inflater.inflate(R.layout.main_list, null);

    btnSlide = (ImageView) app.findViewById(R.id.ib_slide_menu);
    btnSlide.setOnClickListener(new ClickListenerForScrolling(scrollView, menu));      

    fAdsSearch = (AdsSearchFragment)getSupportFragmentManager().findFragmentById(R.id.f_search);
    fActionbar = (ActionBarFragment) getSupportFragmentManager().findFragmentById(R.id.f_actionbar);
    fAdsSearch.setTargetFragment(getSupportFragmentManager().findFragmentById(R.id.f_main), 0);
scrollView.initViews(new View[] {menu, app}, 1, new SizeCallbackForMenu(btnSlide));
}

slide_menu.xml：源代码

<?xml version="1.0" encoding="utf-8"?>
<CustomHorizontalScrollView 
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" 
android:layout_height="fill_parent" 
android:background="#00ffffff" 
android:padding="0px"
android:layout_margin="0px" 
android:fadingEdge="none" 
android:fadingEdgeLength="0px"
android:scrollbars="none">
<LinearLayout 
    android:id="@+id/top" 
    android:layout_height="fill_parent" 
    android:layout_width="fill_parent"
    android:orientation="horizontal" 
    android:background="#ffffffff" 
    android:padding="0px" 
    android:layout_margin="0px">
</LinearLayout>
</CustomHorizontalScrollView>

horz_scroll_menu.xml：源代码

<?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:orientation="vertical" >
<fragment
    android:id="@+id/f_filter_menu"
    android:name="MenuFragment"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >
</fragment>
</LinearLayout>

main_list.xml：源代码

<?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:orientation="vertical" >
<fragment
    android:id="@+id/f_actionbar"
    android:name="ActionBarFragment"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" />
<fragment
    android:id="@+id/f_search"
    android:name="SearchFragment"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" />
<fragment
    android:id="@+id/f_main"
    android:name="MainFragment"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" />
</LinearLayout>

日志错误：

02-08 15:57:12.959: E/AndroidRuntime(19322): FATAL EXCEPTION: main
02-08 15:57:12.959: E/AndroidRuntime(19322): java.lang.NullPointerException
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.Spinner.makeAndAddView(Spinner.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.Spinner.layout(Spinner.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.Spinner.onLayout(Spinner.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.View.layout(View.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.ViewGroup.layout(ViewGroup.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.setChildFrame(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.layoutHorizontal(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.onLayout(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.View.layout(View.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.ViewGroup.layout(ViewGroup.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.setChildFrame(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.layoutVertical(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.onLayout(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.View.layout(View.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.ViewGroup.layout(ViewGroup.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.FrameLayout.onLayout(FrameLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.View.layout(View.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.ViewGroup.layout(ViewGroup.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.setChildFrame(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.layoutVertical(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.onLayout(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.View.layout(View.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.ViewGroup.layout(ViewGroup.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.setChildFrame(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.layoutHorizontal(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.onLayout(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.View.layout(View.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.ViewGroup.layout(ViewGroup.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.FrameLayout.onLayout(FrameLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.HorizontalScrollView.onLayout(HorizontalScrollView.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.View.layout(View.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.ViewGroup.layout(ViewGroup.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.FrameLayout.onLayout(FrameLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.View.layout(View.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.ViewGroup.layout(ViewGroup.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.setChildFrame(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.layoutVertical(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.LinearLayout.onLayout(LinearLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.View.layout(View.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.ViewGroup.layout(ViewGroup.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.widget.FrameLayout.onLayout(FrameLayout.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.View.layout(View.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.ViewGroup.layout(ViewGroup.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.os.Handler.dispatchMessage(Handler.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.os.Looper.loop(Looper.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at android.app.ActivityThread.main(ActivityThread.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at java.lang.reflect.Method.invokeNative(Native Method)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at java.lang.reflect.Method.invoke(Method.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java)
02-08 15:57:12.959: E/AndroidRuntime(19322):    at dalvik.system.NativeStart.main(Native Method)

score 0 · Accepted Answer

原来这个 NullPointerException 和滑动菜单无关。这是因为我通过将适配器设置为 null 来清理列表数据。感谢你的帮助。

android - 水平滑动菜单调用Activity，恢复后导致NullPointerException

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