FragmentStatePagerAdapter with Glide 的使用会导致 NullPointerExcep

Question

一些背景：

我正在使用FragmentStatePagerAdapter来实现可变数量的片段的水平滑动视图。澄清一下，片段的数量取决于一些外部数据。在这种情况下，并且片段的数量可能非常大，我无法使用适配器的setOffScreenPageLimit()方法。

现在，进入问题：

我正在使用 Glide 从网络上检索图像列表并将它们显示在我的片段上。这适用于第一个片段，也适用于第二个片段(因为setOffScreenPageLimit()默认为1)。

但是，第 3 个片段超出了 setOffScreenPageLimit() 范围。当我尝试在这个片段上检索图像时，我从某个内部 Glide 方法中得到一个 NullPointerException，该方法在片段上调用 getView()(这显然是空的)。我已经确认这实际上是问题所在，例如，当我将屏幕外限制设置为 4 时，当我尝试检索第 5 个片段上的图像时，应用程序崩溃。

这是我的日志输出：

java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.support.v4.app.Fragment.getView()' on a null object reference
    at com.bumptech.glide.manager.RequestManagerRetriever.findAllSupportFragmentsWithViews(RequestManagerRetriever.java:189)
    at com.bumptech.glide.manager.RequestManagerRetriever.findSupportFragment(RequestManagerRetriever.java:200)
    at com.bumptech.glide.manager.RequestManagerRetriever.get(RequestManagerRetriever.java:167)
    at com.bumptech.glide.Glide.with(Glide.java:609)
    at com.android.miki.quickly.GIFRecyclerAdapter.onViewRecycled(GIFRecyclerAdapter.java:51)
    at com.android.miki.quickly.GIFRecyclerAdapter.onViewRecycled(GIFRecyclerAdapter.java:17)
    at android.support.v7.widget.RecyclerView$Recycler.dispatchViewRecycled(RecyclerView.java:6056)
    at android.support.v7.widget.RecyclerView$Recycler.addViewHolderToRecycledViewPool(RecyclerView.java:5827)
    at android.support.v7.widget.RecyclerView$Recycler.recycleViewHolderInternal(RecyclerView.java:5792)
    at android.support.v7.widget.RecyclerView$LayoutManager.scrapOrRecycleView(RecyclerView.java:8462)
    at android.support.v7.widget.RecyclerView$LayoutManager.detachAndScrapAttachedViews(RecyclerView.java:8447)
    at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:563)
    at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3583)
    at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3312)
    at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3844)
    at android.view.View.layout(View.java:17637)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
    at android.view.View.layout(View.java:17637)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1079)
    at android.view.View.layout(View.java:17637)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1795)
    at android.view.View.layout(View.java:17637)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:17637)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1079)
    at android.view.View.layout(View.java:17637)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:17637)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
    at android.view.View.layout(View.java:17637)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:17637)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
    at android.view.View.layout(View.java:17637)
    at android.view.ViewGroup.layout(ViewGroup.java:5575)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)

以下是 GIFRecyclerAdapter 类：

public class GIFRecyclerAdapter extends RecyclerView.Adapter<GIFRecyclerAdapter.GifViewHolder>{

private List<String> gifURLs;
public GIFRecyclerAdapter(List<String> gifURLs) {
this.gifURLs = gifURLs;
}
@Override
public GifViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.single_gif, parent, false);
GifViewHolder vh = new GifViewHolder(v);
return vh;
}
@Override
public void onBindViewHolder(GifViewHolder holder, int position) {
holder.setGif(gifURLs.get(position));
}
@Override
public int getItemCount() {
return gifURLs.size();
}
public void setURLs(List<String> gifURLs) {
this.gifURLs = gifURLs;
}
@Override
public void onViewRecycled(GifViewHolder holder){
super.onViewRecycled(holder);
Glide.with(holder.itemView).clear(holder.mImageViewGif);
}

protected class GifViewHolder extends RecyclerView.ViewHolder {
private ImageView mImageViewGif;
private GifViewHolder(View itemView) {
super(itemView);
mImageViewGif = (ImageView) itemView.findViewById(R.id.gif_image_view);
}
private void setGif(String gifURL) {
try{
Glide.with(this.itemView).load(gifURL).into(mImageViewGif);
} catch (Exception e) {
e.printStackTrace();
}
}
}

}

谁能给我一些提示，为什么会发生这种情况？片段出现在屏幕上，UI的其余部分工作正常(可以按下按钮等)。但是，使用 Glide 加载图像会使应用程序崩溃。我有一种感觉，这是某种生命周期细节，与FragmentStatePagerAdapter如何创建和销毁片段有关，但我不确定。

任何帮助将不胜感激。

Answer 1

我认为这条线Glide.with(this.itemView)有问题。

只需将上下文从活动传递给适配器，然后使用它 this.itemView

另一种快速解决方法可能是Glide.with(mİmageView.getContext())

祝你好运

埃姆雷