java.lang.IllegalArgumentException：观察者为空
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java.lang.IllegalArgumentException: The observer is null
提问by aheuermann
A user of one of my apps reported this error. I'm confused as to what it means an how to fix it. After a bit of googling...still no luck. Anyone seen this before or know how to fix it?
我的一个应用程序的用户报告了此错误。我对这意味着什么以及如何修复它感到困惑。经过一些谷歌搜索......仍然没有运气。任何人以前见过这个或知道如何解决它？
java.lang.IllegalArgumentException: The observer is null.
at android.database.Observable.unregisterObserver(Observable.java:59)
at android.widget.BaseAdapter.unregisterDataSetObserver(BaseAdapter.java:42)
at android.widget.HeaderViewListAdapter.unregisterDataSetObserver(HeaderViewListAdapter.java:256)
at android.widget.AbsListView.onDetachedFromWindow(AbsListView.java:2309)
at android.view.View.dispatchDetachedFromWindow(View.java:8197)
at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:1968)
at android.view.ViewGroup.dispatchDetachedFromWindow(ViewGroup.java:1966)
at android.view.ViewGroup.removeViewInternal(ViewGroup.java:3257)
at android.view.ViewGroup.removeViewInternal(ViewGroup.java:3237)
at android.view.ViewGroup.removeView(ViewGroup.java:3185)
at com.aheudev.a.slickdeals.adapters.DealPageAdapter.destroyItem(DealPageAdapter.java:174)
at android.support.v4.view.ViewPager.populate(ViewPager.java:415)
at android.support.v4.view.ViewPager.completeScroll(ViewPager.java:696)
at android.support.v4.view.ViewPager.computeScroll(ViewPager.java:668)
at android.view.ViewGroup.drawChild(ViewGroup.java:2434)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2189)
at android.view.View.draw(View.java:9282)
at android.view.ViewGroup.drawChild(ViewGroup.java:2584)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2189)
at android.view.ViewGroup.drawChild(ViewGroup.java:2582)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2189)
at android.view.ViewGroup.drawChild(ViewGroup.java:2582)
at android.view.ViewGroup.dispatchDraw(ViewGroup.java:2189)
at android.view.View.draw(View.java:9282)
at android.widget.FrameLayout.draw(FrameLayout.java:419)
at com.android.internal.policy.impl.PhoneWindow$DecorView.draw(PhoneWindow.java:1923)
at android.view.ViewRoot.draw(ViewRoot.java:1695)
at android.view.ViewRoot.performTraversals(ViewRoot.java:1410)
at android.view.ViewRoot.handleMessage(ViewRoot.java:2040)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:132)
at android.app.ActivityThread.main(ActivityThread.java:4123)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
at dalvik.system.NativeStart.main(Native Method)
And it came from this function in my PagerAdapter:
它来自我的 PagerAdapter 中的这个函数：
@Override
public void destroyItem(View collection, int position, Object view) {
((ViewPager) collection).removeView((View) view);
}
回答by vm204
I too was having the same problem and it seems that unregisterDataSetObserver on your DealPageAdapter is being called twice. To fix the problem I overwrote the unregisterDataSetObserver in my Adapter as such
我也遇到了同样的问题，似乎您的 DealPageAdapter 上的 unregisterDataSetObserver 被调用了两次。为了解决这个问题，我在我的适配器中覆盖了 unregisterDataSetObserver
@Override
public void unregisterDataSetObserver(DataSetObserver observer) {
if (observer != null) {
super.unregisterDataSetObserver(observer);
}
}
Hope this helps!
希望这可以帮助！
回答by Preston
There are a few people who have had your problem Hereand Here
From looking at the call stack it looks like your "view" registered a observer that it's now trying to unregister. That observer is no longer there even though it's expected. Hence the error. This might be a bug or it might be related to how you're doing things.
从调用堆栈来看，您的“视图”似乎注册了一个正在尝试取消注册的观察者。即使在意料之中，那个观察者也不再存在了。因此错误。这可能是一个错误，也可能与您的工作方式有关。
Trying looking through the Android Sourceto see if you can track it down.
尝试查看Android 源，看看您是否可以找到它。
Good luck.
祝你好运。
回答by H.S.H
An alternative solution is to wrap the ListView and catch the exception. This solution worked for me, and I have yet not found any side effects.
另一种解决方案是包装 ListView 并捕获异常。这个解决方案对我有用，我还没有发现任何副作用。
public class CustumListView extends ListView {public CustumListView(Context context, AttributeSet attrs) { super(context, attrs); } @Override protected void onDetachedFromWindow() { try { super.onDetachedFromWindow(); } catch(IllegalArgumentException iae) { } } }
