java - 如何实时修改 View-pager
问题描述
我,是安卓新手。我创建了一个从 firebase 获取图像的视图寻呼机。它工作正常。但是该视图寻呼机中存在一些我未能解决的漏洞。
1) 我的 View-pager 没有实时更新。意味着当我在firebase中修改图像时。它不会实时影响。我必须关闭我的应用程序,然后必须重新启动它才能看到这些更新。
2)当我从我的firebase列表中删除项目时。我的应用程序崩溃了,在 Logcat 中抛出了这个异常。
java.lang.IndexOutOfBoundsException: Index: -1, Size: 5
at java.util.ArrayList.add(ArrayList.java:483)
at com.release.pack.lootbox.Fragments.HomeFragment$7.onEvent(HomeFragment.java:294)
at com.release.pack.lootbox.Fragments.HomeFragment$7.onEvent(HomeFragment.java:281)
这是我的代码:
滑块图像适配器:
public class SliderImageAdapter extends SliderViewAdapter<SliderImageAdapter.SliderAdapterVH> {
public List<Banner> bannerList;
public Context context;
public SliderImageAdapter(Context context, List<Banner> bannerList) {
this.bannerList = bannerList;
this.context = context;
}
@Override
public SliderAdapterVH onCreateViewHolder(ViewGroup parent) {
View inflate = LayoutInflater.from(parent.getContext()).inflate(R.layout.image_slider_myshop, parent, false);
return new SliderAdapterVH(inflate);
}
@Override
public void onBindViewHolder(final SliderAdapterVH viewHolder, final int position) {
Glide.with(viewHolder.itemView)
.load(bannerList.get(position).getmSliderImage())
.fitCenter()
.into(viewHolder.imageViewBackground);
}
@Override
public int getCount() {
return bannerList.size();
}
class SliderAdapterVH extends SliderViewAdapter.ViewHolder {
View itemView;
ImageView imageViewBackground;
ImageView imageGifContainer;
TextView textViewDescription;
public ProgressBar progressBar;
public ImageView imageViewFailed;
public SliderAdapterVH(View itemView) {
super(itemView);
imageViewBackground = itemView.findViewById(R.id.iv_auto_image_slider);
imageGifContainer = itemView.findViewById(R.id.iv_gif_container);
textViewDescription = itemView.findViewById(R.id.tv_auto_image_slider);
progressBar = itemView.findViewById(R.id.featured_deal_progress);
imageViewFailed = itemView.findViewById(R.id.featured_deal_img_failed_to_load);
this.itemView = itemView;
}
}
}
家庭片段:
private SliderImageAdapter sliderImageAdapter;
private List<Banner> bannerList;
bannerList = new ArrayList<>();
sliderImageAdapter = new SliderImageAdapter(getActivity(),bannerList);
sliderMyshop = view.findViewById(R.id.imageSlider);
sliderMyshop.setSliderAdapter(sliderImageAdapter);
sliderMyshop.setIndicatorAnimation(IndicatorAnimations.WORM); //set indicator animation by using SliderLayout.IndicatorAnimations. :WORM or THIN_WORM or COLOR or DROP or FILL or NONE or SCALE or SCALE_DOWN or SLIDE and SWAP!!
sliderMyshop.setSliderTransformAnimation(SliderAnimations.SIMPLETRANSFORMATION);
sliderMyshop.setIndicatorSelectedColor(Color.WHITE);
sliderMyshop.setIndicatorUnselectedColor(Color.GRAY);
sliderMyshop.startAutoCycle();
mFirestore.collection("Banner").orderBy("priority", Query.Direction.DESCENDING).addSnapshotListener(new EventListener<QuerySnapshot>() {
@Override
public void onEvent(@javax.annotation.Nullable QuerySnapshot documentSnapshots, @javax.annotation.Nullable FirebaseFirestoreException e) {
if (e != null) {
Log.d(TAG, "Error : " + e.getMessage());
}
assert documentSnapshots != null;
for (DocumentChange doc : documentSnapshots.getDocumentChanges()) {
if (doc.getType() == DocumentChange.Type.ADDED) {
String doc_id = doc.getDocument().getId();
Banner banner = doc.getDocument().toObject(Banner.class).withDocId(doc_id);
bannerList.add(doc.getNewIndex(), banner);
sliderImageAdapter.notifyDataSetChanged();
} else if (doc.getType() == DocumentChange.Type.MODIFIED) {
String docID = doc.getDocument().getId();
Banner changedModel = doc.getDocument().toObject(Banner.class).withDocId(docID);
if (doc.getOldIndex() == doc.getNewIndex()) {
// Item changed but remained in same position
bannerList.set(doc.getOldIndex(), changedModel);
// sliderImageAdapter.notifyItemChanged(doc.getOldIndex());
} else {
// Item changed and changed position
bannerList.remove(doc.getOldIndex());
bannerList.add(doc.getNewIndex(), changedModel);
// sliderImageAdapter.notifyItemMoved(doc.getOldIndex(), doc.getNewIndex());
}
} else if (doc.getType() == DocumentChange.Type.REMOVED) {
// remove
bannerList.remove(doc.getOldIndex());
// sliderImageAdapter.notifyItemRemoved(doc.getOldIndex());
}
}
}
});
当我在 firebase 中添加新图像时,它会实时更新。但不是当我在我的图像中进行修改时。或从我的列表中删除该项目。
解决方案
坠毁
bannerList.add(doc.getNewIndex(), banner);
这一行是IndexOutOfBoundsException的原因。
(java.lang.IndexOutOfBoundsException: Index: -1, Size: 5)
doc.getNewIndex()
正在返回-1。并且 list 不能接受 -1 作为索引。所以请检查你的doc.getNewIndex()
.
实时更新
bannerList.clear();
在您的for循环之前添加此代码,否则将添加冗余数据并且您无法更新新更改。
请参阅:快照处理程序将在每次查询结果更改时(即添加、删除或修改文档时)接收新的查询快照。
对于每次更改,都会获取整个集合
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