Java 如何使用LiveData更新RecyclerView示例：参见计数器、CommentCounter、LikeCounter

所以我使用RecyclerView制作社交媒体应用程序，它有like按钮和like计数器，当MainActivity load OnCreate时，它会点击“http//test/getLikeCounter”在我的RecyclerView中显示like计数器，但当我点击like按钮时，它会点击我自己的API“http//test/setLikeCounter”，并在我的数据库中添加计数器，但因为它不会再次加载OnCreate方法，所以它不会在我的RecyclerView中添加我的Like计数器，当我单击Like按钮时，我应该如何动态刷新我的RecyclerView？ 有人建议使用LiveData，但是如何以及在何处实现它呢

这是当我在OnCreate中点击我的API时，它将在WebAPI.java中点击“http//test/getLikeCounter”

webAPI_.rncryptorALLDEWA("Trending");

我通过点击API接收数据并转换JSON文件，然后使用EventBus将其发送回MainActivity

@Subscribe(threadMode = ThreadMode.MAIN)
public void onMessageEvent(MainActivity.EventStoredTrending event) {
    getTrendingMainActivity(event.SendDummyUrutan, event.SendTotalThread, event.SendDummyIDContent, event.SendDummyTitle, event.SendDummyPublishTime, event.SendDummyImageOri, event.SendDummyShortDescription, event.SendDummySeen, event.SendDummyComment, event.SendDummyLike);
}

之后，我手动将该值设置为我的RecyclerView

public void createDummyData1UPDATE(int ReceivedDummyUrutan, int ReceivedTotalThread, String ReceivedDummyIDContent, String ReceivedDummyTitle, String ReceivedDummyPublishTime, String ReceivedDummyImageOri, String ReceivedDummyShortDescription, int ReceivedDummySeen, int ReceivedDummyComment, int ReceivedDummyLike, int ReceivedDummyisComment, int ReceivedDummyisLike, int ReceivedDummyisBookmark) {
    modelSingleHotTrendingNews.add(new ModelSingleHotTrendingNews(ReceivedDummyIDContent, ReceivedDummyTitle, ReceivedDummyPublishTime, ReceivedDummyImageOri, ReceivedDummyShortDescription, ReceivedDummySeen, ReceivedDummyComment, ReceivedDummyLike, ReceivedDummyisComment, ReceivedDummyisLike, ReceivedDummyisBookmark,"x53535", "No Error"));

    if(ReceivedDummyUrutan ==  ReceivedTotalThread-1){
        ModelSectionHotTrendingNews modelSectionHotTrendingNewsX = new ModelSectionHotTrendingNews();
        modelSectionHotTrendingNewsX.setHeaderTitle("TRENDING NEWS");
        modelSectionHotTrendingNewsX.setAllItemsInSection(modelSingleHotTrendingNews);
        modelSectionHotTrendingNews.add(modelSectionHotTrendingNewsX);

        RecyclerViewSingleHotTrendingNews = v.findViewById(R.id.RecyclerView_Single_HotTrendingNews);
        RecyclerViewSingleHotTrendingNews.setHasFixedSize(true);
        adapterSectionHotTrendingNews = new AdapterSectionHotTrendingNews(getActivity(), modelSectionHotTrendingNews, listenerHotTrendingNews);
        RecyclerViewSingleHotTrendingNews.setLayoutManager(new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false));
        RecyclerViewSingleHotTrendingNews.setAdapter(adapterSectionHotTrendingNews);
        //Optimized
        RecyclerViewSingleHotLatestNews.setHasFixedSize(true);
        RecyclerViewSingleHotLatestNews.setItemViewCacheSize(20);
    }

}

当我点击一个like按钮时，我想更新到我的RecyclerView，所以当数据库中的“LikeCounter”增加时，RecyclerView会动态更新

webAPI_.rncryptorCommentLikeBookmark("isLike", modelSingleHotTrendingNews.get(position).getIdcontent(), modelSingleHotTrendingNews.get(position).getIslike());

这是HotSectionAdapter.java

public class AdapterSectionHotTrendingNews extends RecyclerView.Adapter{

private Context mContext;
private ArrayList<ModelSectionHotTrendingNews> modelSectionHotTrendingNews;
private AdapterSingleHotTrendingNews.RecyclerViewClickListener mListener;

public AdapterSectionHotTrendingNews(Context mContext, ArrayList<ModelSectionHotTrendingNews> modelSectionHotTrendingNews, AdapterSingleHotTrendingNews.RecyclerViewClickListener mListener) {
    this.mContext = mContext;
    this.modelSectionHotTrendingNews = modelSectionHotTrendingNews;
    this.mListener = mListener;
}



@Override
        public SectionHotTrendingNewsViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_section_hottrendingnews, null);
    return new SectionHotTrendingNewsViewHolder(v);
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) {

    final SectionHotTrendingNewsViewHolder sectionHotTrendingNewsViewHolder = (SectionHotTrendingNewsViewHolder) holder;
    ModelSectionHotTrendingNews modelSectionHotTrendingNewsX = modelSectionHotTrendingNews.get(position);

    //Set
    sectionHotTrendingNewsViewHolder.TVSectionTitle.setText(modelSectionHotTrendingNewsX.getHeaderTitle());

    ArrayList singleSectionItems = modelSectionHotTrendingNewsX.getAllItemsInSection();

    //WOW
    AdapterSingleHotTrendingNews itemListDataAdapter = new AdapterSingleHotTrendingNews(mContext, singleSectionItems, mListener);
    //WOW

    final String sectionTitle = modelSectionHotTrendingNewsX.getHeaderTitle();
    sectionHotTrendingNewsViewHolder.BTNHotTrendingNewsMore.setOnClickListener(
            new View.OnClickListener() { @Override public void onClick(View v) {
                Toast.makeText(v.getContext(), "click event on more, "+sectionTitle, Toast.LENGTH_SHORT).show();
                Intent intent = new Intent(mContext, TabMoreHotActivity.class);
                // here you create put extra in new intent not the intent that you created

                intent.putExtra("MoreTrendingNews", modelSectionHotTrendingNews.get(position).getAllItemsInSection());
                mContext.startActivity(intent);

            } });




    /*Glide.with(mContext)
            .load(feedItem.getImageURL())
            .diskCacheStrategy(DiskCacheStrategy.ALL)
            .centerCrop()
            .error(R.drawable.bg)
            .into(feedListRowHolder.thumbView);*/

    //SetRecyclerView
    sectionHotTrendingNewsViewHolder.RecyclerViewSectionHotTrendingNews.setHasFixedSize(true);
    sectionHotTrendingNewsViewHolder.RecyclerViewSectionHotTrendingNews.setLayoutManager(new LinearLayoutManager(mContext, LinearLayoutManager.HORIZONTAL, false));
    sectionHotTrendingNewsViewHolder.RecyclerViewSectionHotTrendingNews.setAdapter(itemListDataAdapter);
    sectionHotTrendingNewsViewHolder.RecyclerViewSectionHotTrendingNews.setNestedScrollingEnabled(false);
}

@Override
public int getItemCount() {
    int itemCount = modelSectionHotTrendingNews.size();
    return itemCount;
}

public class SectionHotTrendingNewsViewHolder extends RecyclerView.ViewHolder {

    protected TextView TVSectionTitle;
    protected ImageView BTNHotTrendingNewsMore;
    protected RecyclerView RecyclerViewSectionHotTrendingNews;
    protected RecyclerView RecyclerViewMoreSectionHotTrendingNews;

    public SectionHotTrendingNewsViewHolder(View itemView) {
        super(itemView);

        TVSectionTitle = (TextView) itemView.findViewById(R.id.TV_SectionTitle);
        BTNHotTrendingNewsMore= (ImageView) itemView.findViewById(R.id.BTN_HotTrendingNewsMore);
        RecyclerViewSectionHotTrendingNews = (RecyclerView) itemView.findViewById(R.id.RecyclerView_Section_HotTrendingNews);
        RecyclerViewMoreSectionHotTrendingNews = (RecyclerView) itemView.findViewById(R.id.RecyclerViewMore_Section_HotTrendingNews);
    }

}

public class AdapterSingleHotTrendingNews extends RecyclerView.Adapter{

private Context mContext;
private ArrayList<ModelSingleHotTrendingNews> modelSingleHotTrendingNews;

private RecyclerViewClickListener mListener;


public AdapterSingleHotTrendingNews(Context mContext, ArrayList<ModelSingleHotTrendingNews> modelSingleHotTrendingNews, RecyclerViewClickListener mListener) {
    this.mContext = mContext;
    this.modelSingleHotTrendingNews = modelSingleHotTrendingNews;
    this.mListener = mListener;
}

/*public void swap(ArrayList<ModelSingleHotTrendingNews> datas)
{
    modelSingleHotTrendingNews.clear();
    modelSingleHotTrendingNews.addAll(datas);
    notifyDataSetChanged();
}*/

public void swap(ArrayList list){
    if (modelSingleHotTrendingNews != null) {
        modelSingleHotTrendingNews.clear();
        modelSingleHotTrendingNews.addAll(list);
    }
    else {
        modelSingleHotTrendingNews = list;
    }
    notifyDataSetChanged();
}

//Container
@Override
public SingleHotTrendingNewsViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
    View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.item_single_hottrendingnews, null);
    return new SingleHotTrendingNewsViewHolder(v, mListener);
}

//Fill Container with Model Setter Getter
@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, final int position) {

    final SingleHotTrendingNewsViewHolder singleHotTrendingNewsViewHolder = (SingleHotTrendingNewsViewHolder) holder;
    final ModelSingleHotTrendingNews modelSingleHotTrendingNewsX = modelSingleHotTrendingNews.get(position);

    //Set
    singleHotTrendingNewsViewHolder.TVGameDate.setText(modelSingleHotTrendingNewsX.getGamedate());
    singleHotTrendingNewsViewHolder.TVGameTitle.setText(modelSingleHotTrendingNewsX.getGametitle());
    Glide.with(mContext).load(modelSingleHotTrendingNewsX.getGameimage()).into(singleHotTrendingNewsViewHolder.IMGGameImage);
    /*singleHotTrendingNewsViewHolder.IMGGameImage.setImageResource(modelSingleHotTrendingNewsX.getGameimage());*/

    singleHotTrendingNewsViewHolder.TVSeenCounter.setText(String.valueOf(modelSingleHotTrendingNewsX.getSeencounter()));
    singleHotTrendingNewsViewHolder.TVCommentCounter.setText(String.valueOf(modelSingleHotTrendingNewsX.getCommentcounter()));
    singleHotTrendingNewsViewHolder.TVLikeCounter.setText(String.valueOf(modelSingleHotTrendingNewsX.getLikecounter()));

    if(modelSingleHotTrendingNewsX.getIscomment() == 0){
        singleHotTrendingNewsViewHolder.IMGCommentView.setImageResource(R.drawable.comment_off);
    }else if(modelSingleHotTrendingNewsX.getIscomment() == 1){
        singleHotTrendingNewsViewHolder.IMGCommentView.setImageResource(R.drawable.comment_on);
    }

    if(modelSingleHotTrendingNewsX.getIslike() == 0){
        singleHotTrendingNewsViewHolder.IMGLikeView.setImageResource(R.drawable.heart_off);
    }else if(modelSingleHotTrendingNewsX.getIslike() == 1){
        singleHotTrendingNewsViewHolder.IMGLikeView.setImageResource(R.drawable.heart_on);
    }

    if(modelSingleHotTrendingNewsX.getTrendingnewssaving() == 0) {
        singleHotTrendingNewsViewHolder.ICONHotTrendingNewsSaving.setImageResource(R.drawable.saved_off);
        singleHotTrendingNewsViewHolder.ICONHotTrendingNewsSaving.setVisibility(View.GONE);
    }else if(modelSingleHotTrendingNewsX.getTrendingnewssaving() == 1) {
        singleHotTrendingNewsViewHolder.ICONHotTrendingNewsSaving.setImageResource(R.drawable.saved_on);
    }

    singleHotTrendingNewsViewHolder.ICONHotTrendingNewsSaving.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            final int booltrendingnewssaving = modelSingleHotTrendingNewsX.getTrendingnewssaving();

            final String idcontent = modelSingleHotTrendingNewsX.getIdcontent();

            if (booltrendingnewssaving == 1){
                Toast.makeText(v.getContext(), "Turn Off Saved News " + idcontent, Toast.LENGTH_SHORT).show();
                singleHotTrendingNewsViewHolder.ICONHotTrendingNewsSaving.setImageResource(R.drawable.saved_off);
                modelSingleHotTrendingNewsX.setTrendingnewssaving(0);
                /*updateSavedNewsSaving("update_newssaving", id, false);*/
            } else if(booltrendingnewssaving == 0) {
                Toast.makeText(v.getContext(), "Turn On Saved News " + idcontent, Toast.LENGTH_SHORT).show();
                singleHotTrendingNewsViewHolder.ICONHotTrendingNewsSaving.setImageResource(R.drawable.saved_on);
                modelSingleHotTrendingNewsX.setTrendingnewssaving(1);
                /*updateSavedNewsSaving("update_newssaving", id, true);*/
            }
        }
    });



   /* Glide.with(mContext)
            .load(feedItem.getImageURL())
            .diskCacheStrategy(DiskCacheStrategy.ALL)
            .centerCrop()
            .error(R.drawable.bg)
            .into(feedListRowHolder.thumbView);*/

    /*singleHotTrendingNewsViewHolder.ROWHotTrendingNewsContainer.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Toast.makeText(v.getContext(), modelSingleHotTrendingNews.get(position).getGamedescription(), Toast.LENGTH_SHORT).show();

            //Passing Data to GameDescriptionActivity
            Intent intent = new Intent(mContext, GameDetailActivity.class);
            intent.putExtra("ImagePKG",  modelSingleHotTrendingNews.get(position).getGameimage());
            intent.putExtra("NamePKG",  modelSingleHotTrendingNews.get(position).getGamedate());
            intent.putExtra("UrlPKG",  modelSingleHotTrendingNews.get(position).getIdcontent());
            intent.putExtra("DescriptionPKG",  modelSingleHotTrendingNews.get(position).getGametitle());
            mContext.startActivity(intent);
        }
    });*/
}

@Override
public int getItemCount() {
    int itemCount = modelSingleHotTrendingNews.size();
    return itemCount;
}

public class SingleHotTrendingNewsViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
    TextView TVGameDate;
    TextView TVGameTitle;
    ImageView IMGGameImage;

    TextView TVSeenCounter;
    TextView TVCommentCounter;
    TextView TVLikeCounter;

    ImageView IMGSeenView;
    ImageView IMGCommentView;
    ImageView IMGLikeView;

    ImageView ICONHotTrendingNewsSaving;
    private RelativeLayout ROWHotTrendingNewsContainer;

    private RecyclerViewClickListener mListener;


    public SingleHotTrendingNewsViewHolder(View itemView, RecyclerViewClickListener listener) {
        super(itemView);

        TVGameDate = itemView.findViewById(R.id.TV_GameDate);
        TVGameTitle = itemView.findViewById(R.id.TV_GameTitle);
        IMGGameImage = itemView.findViewById(R.id.IMG_GameImage);

        TVSeenCounter = itemView.findViewById(R.id.TV_SeenCounter);
        TVCommentCounter = itemView.findViewById(R.id.TV_CommentCounter);
        TVLikeCounter = itemView.findViewById(R.id.TV_LikeCounter);

        IMGSeenView = itemView.findViewById(R.id.IMG_SeenView);
        IMGCommentView = itemView.findViewById(R.id.IMG_CommentView);
        IMGLikeView = itemView.findViewById(R.id.IMG_LikeView);

        ICONHotTrendingNewsSaving = itemView.findViewById(R.id.ICON_HotTrendingNewsSaving);
        ROWHotTrendingNewsContainer = itemView.findViewById(R.id.ROW_HotTrendingNewsContainer);

        mListener = listener;
        ROWHotTrendingNewsContainer.setOnClickListener(this);
        IMGCommentView.setOnClickListener(this);
        IMGLikeView.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.ROW_HotTrendingNewsContainer:
                mListener.onRowHotTrendingNewsContainerClick(ROWHotTrendingNewsContainer, getAdapterPosition());
                break;
            case R.id.IMG_CommentView:
                mListener.onRowCommentViewClick(IMGCommentView, getAdapterPosition());
                break;
            case R.id.IMG_LikeView:
                mListener.onRowLikeViewClick(IMGLikeView, getAdapterPosition());
                break;
            default:
                break;
        }
    }
}

public interface RecyclerViewClickListener {
    void onRowHotTrendingNewsContainerClick(View view, int position);
    void onRowCommentViewClick(View view, int position);
    void onRowLikeViewClick(View view, int position);
}

---

}

因此您在MainActivity（使用EventBus）中有一个响应事件，这是将元素（从api返回）添加到列表的正确位置，然后使用notifyDataSetChanged刷新适配器

您有两个适配器，因此在mainActivity中，您需要该适配器的一个实例，以便使用数据刷新该实例

adapter.setItems(list); 
adapter.notifyDataSetChanged();

您也可以在单击类似项时将新元素添加到列表中，但如果出现某些db错误，则列表将刷新，但您将与db不同步，因此最好使用evenbus响应

public class ModelSingleHotTrendingNews implements Serializable {

private String idcontent;
private String gametitle;

private String gamedate;
private String gameimage;
private String gamedescription;

private int seencounter;
private int commentcounter;
private int likecounter;

private int iscomment;
private int islike;
private int trendingnewssaving;

private String value;
private String message;

public ModelSingleHotTrendingNews(String idcontent, String gametitle, String gamedate, String gameimage, String gamedescription, int seencounter, int commentcounter, int likecounter, int iscomment, int islike, int trendingnewssaving, String value, String message) {
    this.idcontent = idcontent;
    this.gametitle = gametitle;
    this.gamedate = gamedate;
    this.gameimage = gameimage;
    this.gamedescription = gamedescription;
    this.seencounter = seencounter;
    this.commentcounter = commentcounter;
    this.likecounter = likecounter;
    this.iscomment = iscomment;
    this.islike = islike;
    this.trendingnewssaving = trendingnewssaving;
    this.value = value;
    this.message = message;
}

public String getIdcontent() {
    return idcontent;
}

public void setIdcontent(String idcontent) {
    this.idcontent = idcontent;
}

public String getGametitle() {
    return gametitle;
}

public void setGametitle(String gametitle) {
    this.gametitle = gametitle;
}

public String getGamedate() {
    return gamedate;
}

public void setGamedate(String gamedate) {
    this.gamedate = gamedate;
}

public String getGameimage() {
    return gameimage;
}

public void setGameimage(String gameimage) {
    this.gameimage = gameimage;
}

public String getGamedescription() {
    return gamedescription;
}

public void setGamedescription(String gamedescription) {
    this.gamedescription = gamedescription;
}

public int getSeencounter() {
    return seencounter;
}

public void setSeencounter(int seencounter) {
    this.seencounter = seencounter;
}

public int getCommentcounter() {
    return commentcounter;
}

public void setCommentcounter(int commentcounter) {
    this.commentcounter = commentcounter;
}

public int getLikecounter() {
    return likecounter;
}

public void setLikecounter(int likecounter) {
    this.likecounter = likecounter;
}

public int getIscomment() {
    return iscomment;
}

public void setIscomment(int iscomment) {
    this.iscomment = iscomment;
}

public int getIslike() {
    return islike;
}

public void setIslike(int islike) {
    this.islike = islike;
}

public int getTrendingnewssaving() {
    return trendingnewssaving;
}

public void setTrendingnewssaving(int trendingnewssaving) {
    this.trendingnewssaving = trendingnewssaving;
}

public String getValue() {
    return value;
}

public void setValue(String value) {
    this.value = value;
}

public String getMessage() {
    return message;
}

public void setMessage(String message) {
    this.message = message;
}

adapter.setItems(list); 
adapter.notifyDataSetChanged();