java.lang.IllegalArgumentException:观察者为空

我的一个应用程序的用户报告了此错误。我不知道这意味着什么，也不知道如何修复它。在谷歌搜索了一段时间后…还是没有运气。以前有人见过这个或者知道如何修复它吗

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)

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);
}

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有几个人遇到过你的问题

从调用堆栈来看，您的“视图”似乎注册了一个观察器，而它现在正试图注销该观察器。那个观察者已经不在那里了，尽管它是被期待的。因此出现了错误。这可能是一个bug，也可能与您的工作方式有关

试着看看你是否能找到它

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祝你好运。

我也遇到了同样的问题，您的DealPageAdapter上的unregisterDataSetObserver似乎被调用了两次。为了解决这个问题，我在适配器中重写了unregisteredatasetobserver

@Override
public void unregisterDataSetObserver(DataSetObserver observer) {
    if (observer != null) {
        super.unregisterDataSetObserver(observer);
    }
}

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希望这有帮助

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效，我还没有发现任何副作用。

公共类CustumListView扩展了ListView{

公共CustumListView（上下文、属性集属性）{
超级（上下文，attrs）；
}
@凌驾
受保护的无效onDetachedFromWindow（）{
试一试{
super.onDetachedFromWindow（）；
}捕获（IllegalArgumentException iae）{
}
}
}

我找到了答案。 public class CustumListView extends ListView {

  public CustumListView(Context context, AttributeSet attrs) {
    super(context, attrs);
  }

  @Override
  protected void onDetachedFromWindow() {
    try {
      super.onDetachedFromWindow();
    } catch(IllegalArgumentException iae) {

    }
  }
}