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如何在json對象retrofit2 mvvm中解析json數組

[英]how to parse json array inside json object retrofit2 mvvm

 原文  2019-12-02 19:09:32  6   2    android/ json/ mvvm/ retrofit2

問題描述

我有一個 json，該對象內有一個對象 我有一個 json 數組，我制作了 pojo，但就像 mvvm 一樣，我無法弄清楚如何解析它並在 recyclerView（片段）中顯示它，請檢查我的代碼，謝謝這是我的 json

{ 
"response":{ 
  "status":"ok",
  "userTier":"developer",
  "total":2157516,
  "startIndex":1,
  "pageSize":10,
  "currentPage":1,
  "pages":215752,
  "orderBy":"newest",
  "results":[ 
     { 
        "id":"uk-news/2019/dec/02/killer-of-three-elderly-devon-men-found-not-guilty-due-to-insanity",
        "type":"article",
        "sectionId":"uk-news",
        "sectionName":"UK news",
        "webPublicationDate":"2019-12-02T17:53:26Z",
        "webTitle":"Killer of three elderly Devon men found not guilty due to insanity",
        "webUrl":"https://www.theguardian.com/uk-news/2019/dec/02/killer-of-three-elderly-devon-men-found-not-guilty-due-to-insanity",
        "apiUrl":"https://content.guardianapis.com/uk-news/2019/dec/02/killer-of-three-elderly-devon-men-found-not-guilty-due-to-insanity",
        "isHosted":false,
        "pillarId":"pillar/news",
        "pillarName":"News"
     },
     { 
        "id":"football/2019/dec/02/fa-homophobic-chants-west-ham-chelsea-kick-it-out",
        "type":"article",
        "sectionId":"football",
        "sectionName":"Football",
        "webPublicationDate":"2019-12-02T17:53:09Z",
        "webTitle":"FA in discussions after homophobic chants by West Hams fans",
        "webUrl":"https://www.theguardian.com/football/2019/dec/02/fa-homophobic-chants-west-ham-chelsea-kick-it-out",
        "apiUrl":"https://content.guardianapis.com/football/2019/dec/02/fa-homophobic-chants-west-ham-chelsea-kick-it-out",
        "isHosted":false,
        "pillarId":"pillar/sport",
        "pillarName":"Sport"
     },
     { 
        "id":"news/shortcuts/2019/dec/02/jeremy-corbyn-suit-fabric-labour-leader-for-the-many-not-the-few-pinstripes",
        "type":"article",
        "sectionId":"politics",
        "sectionName":"Politics",
        "webPublicationDate":"2019-12-02T17:42:03Z",
        "webTitle":"Socialist pinstripe: the secret message stitched into Jeremy Corbyn’s new suit",
        "webUrl":"https://www.theguardian.com/news/shortcuts/2019/dec/02/jeremy-corbyn-suit-fabric-labour-leader-for-the-many-not-the-few-pinstripes",
        "apiUrl":"https://content.guardianapis.com/news/shortcuts/2019/dec/02/jeremy-corbyn-suit-fabric-labour-leader-for-the-many-not-the-few-pinstripes",
        "isHosted":false,
        "pillarId":"pillar/news",
        "pillarName":"News"
     },
     { 
        "id":"uk-news/2019/dec/02/police-criticised-response-attack-rabbi-in-north-london",
        "type":"article",
        "sectionId":"uk-news",
        "sectionName":"UK news",
        "webPublicationDate":"2019-12-02T17:41:13Z",
        "webTitle":"Police criticised over response to attack on rabbi in north London",
        "webUrl":"https://www.theguardian.com/uk-news/2019/dec/02/police-criticised-response-attack-rabbi-in-north-london",
        "apiUrl":"https://content.guardianapis.com/uk-news/2019/dec/02/police-criticised-response-attack-rabbi-in-north-london",
        "isHosted":false,
        "pillarId":"pillar/news",
        "pillarName":"News"
     },
     { 
        "id":"artanddesign/2019/dec/02/les-tasses-war-and-pissoirs-how-the-debauched-urinals-of-paris-helped-to-beat-the-nazis",
        "type":"article",
        "sectionId":"artanddesign",
        "sectionName":"Art and design",
        "webPublicationDate":"2019-12-02T17:36:28Z",
        "webTitle":"War and pissoirs: how the urinals of Paris helped beat the Nazis",
        "webUrl":"https://www.theguardian.com/artanddesign/2019/dec/02/les-tasses-war-and-pissoirs-how-the-debauched-urinals-of-paris-helped-to-beat-the-nazis",
        "apiUrl":"https://content.guardianapis.com/artanddesign/2019/dec/02/les-tasses-war-and-pissoirs-how-the-debauched-urinals-of-paris-helped-to-beat-the-nazis",
        "isHosted":false,
        "pillarId":"pillar/arts",
        "pillarName":"Arts"
     },
     { 
        "id":"commentisfree/2019/dec/02/trust-in-politics-has-evaporated-now-it-offers-only-fantasy",
        "type":"article",
        "sectionId":"commentisfree",
        "sectionName":"Opinion",
        "webPublicationDate":"2019-12-02T17:36:01Z",
        "webTitle":"Trust in politics has evaporated, now it offers only fantasy | Suzanne Moore",
        "webUrl":"https://www.theguardian.com/commentisfree/2019/dec/02/trust-in-politics-has-evaporated-now-it-offers-only-fantasy",
        "apiUrl":"https://content.guardianapis.com/commentisfree/2019/dec/02/trust-in-politics-has-evaporated-now-it-offers-only-fantasy",
        "isHosted":false,
        "pillarId":"pillar/opinion",
        "pillarName":"Opinion"
     },
     { 
        "id":"film/2019/dec/02/2019-braddies-peter-bradshaw-films-of-the-year",
        "type":"article",
        "sectionId":"film",
        "sectionName":"Film",
        "webPublicationDate":"2019-12-02T17:29:48Z",
        "webTitle":"And the 2019 Braddies go to … Peter Bradshaw's film picks of the year",
        "webUrl":"https://www.theguardian.com/film/2019/dec/02/2019-braddies-peter-bradshaw-films-of-the-year",
        "apiUrl":"https://content.guardianapis.com/film/2019/dec/02/2019-braddies-peter-bradshaw-films-of-the-year",
        "isHosted":false,
        "pillarId":"pillar/arts",
        "pillarName":"Arts"
     },
     { 
        "id":"world/2019/dec/02/christine-lagarde-ecb-should-do-more-to-tackle-climate-emergency",
        "type":"article",
        "sectionId":"world",
        "sectionName":"World news",
        "webPublicationDate":"2019-12-02T17:23:28Z",
        "webTitle":"Lagarde: ECB should do more to tackle climate emergency",
        "webUrl":"https://www.theguardian.com/world/2019/dec/02/christine-lagarde-ecb-should-do-more-to-tackle-climate-emergency",
        "apiUrl":"https://content.guardianapis.com/world/2019/dec/02/christine-lagarde-ecb-should-do-more-to-tackle-climate-emergency",
        "isHosted":false,
        "pillarId":"pillar/news",
        "pillarName":"News"
     },
     { 
        "id":"food/2019/dec/02/robert-neame-obituary",
        "type":"article",
        "sectionId":"food",
        "sectionName":"Food",
        "webPublicationDate":"2019-12-02T17:19:32Z",
        "webTitle":"Robert Neame obituary",
        "webUrl":"https://www.theguardian.com/food/2019/dec/02/robert-neame-obituary",
        "apiUrl":"https://content.guardianapis.com/food/2019/dec/02/robert-neame-obituary",
        "isHosted":false,
        "pillarId":"pillar/lifestyle",
        "pillarName":"Lifestyle"
     },
     { 
        "id":"politics/live/2019/dec/02/general-election-swinson-condemns-johnson-over-trump-friendship-ahead-of-london-visit-live",
        "type":"liveblog",
        "sectionId":"politics",
        "sectionName":"Politics",
        "webPublicationDate":"2019-12-02T17:13:40Z",
        "webTitle":"General election: Johnson insists he opposed early release for terrorists long before London Bridge attack – live news",
        "webUrl":"https://www.theguardian.com/politics/live/2019/dec/02/general-election-swinson-condemns-johnson-over-trump-friendship-ahead-of-london-visit-live",
        "apiUrl":"https://content.guardianapis.com/politics/live/2019/dec/02/general-election-swinson-condemns-johnson-over-trump-friendship-ahead-of-london-visit-live",
        "isHosted":false,
        "pillarId":"pillar/news",
        "pillarName":"News"
     }
  ]
  }
  }

現在這是我的 pojo 課程。

public class NewsResponse {

@SerializedName("response")
private NewsArticle response;

public NewsArticle getResponse() {
    return response;
}

public void setResponse(NewsArticle response) {
    this.response = response;
}

 }

public class NewsArticle {

@SerializedName("results")
private List<Result> results = null;

public List<Result> getResults() {
    return results;
}

public void setResults(List<Result> results) {
    this.results = results;
}
 }

public class Result {


    @SerializedName("sectionName")
    private String sectionName;
    @SerializedName("webTitle")
    private String webTitle;
    @SerializedName("webUrl")
    private String webUrl;

public String getSectionName() {
    return sectionName;
}

public void setSectionName(String sectionName) {
    this.sectionName = sectionName;
}

public String getWebTitle() {
    return webTitle;
}

public void setWebTitle(String webTitle) {
    this.webTitle = webTitle;
}

public String getWebUrl() {
    return webUrl;
}

public void setWebUrl(String webUrl) {
    this.webUrl = webUrl;
   }
   }

這是我的新存儲庫

public class NewsRepository {

private static NewsRepository newsRepository;

public static NewsRepository getInstance(){
    if (newsRepository == null){
        newsRepository = new NewsRepository();
    }
    return newsRepository;
}

private NewsApi newsApi;

public NewsRepository(){
    newsApi = RetrofitService.cteateService(NewsApi.class);
}

public MutableLiveData<NewsResponse> getNews(String key){
   final MutableLiveData<NewsResponse> newsData = new MutableLiveData<>();
    newsApi.getNewsList( key).enqueue(new Callback<NewsResponse>() {
        @Override
        public void onResponse(Call<NewsResponse> call,
                               Response<NewsResponse> response) {
            if (response.isSuccessful()){
                newsData.setValue(response.body());
            }
        }

        @Override
        public void onFailure(Call<NewsResponse> call, Throwable t) {
            newsData.setValue(null);
        }
    });
    return newsData;
}
    }

現在為片段

ublic class NewsFragment extends Fragment {


ArrayList<NewsResponse> articleArrayList = new ArrayList<>();
NewsAdapter newsAdapter;
RecyclerView rvHeadline;

private static final String TAG = "NewsFragment";

private PageViewModel pageViewModel;

public NewsFragment() {
    // Required empty public constructor
}

/**
 * @return A new instance of fragment SpeedDialFragment.
 */
public static NewsFragment newInstance() {
    return new NewsFragment();
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    pageViewModel = ViewModelProviders.of(this).get(PageViewModel.class);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View root = inflater.inflate(R.layout.news_fragment, container, false);
    rvHeadline = root.findViewById(R.id.rvNews);


    pageViewModel.init();
    pageViewModel.getNewsRepository().observe(this, new Observer<NewsResponse>() {
        @Override
        public void onChanged(NewsResponse newsResponse) {
     ** ******      List<NewsArticle> newsArticles = newsResponse.getResponse(); ******
        *******    articleArrayList.addAll(newsArticles);   ********
            newsAdapter.notifyDataSetChanged();
        }
    });

    setupRecyclerView();
    return root;
}
private void setupRecyclerView() {
    if (newsAdapter == null) {
        newsAdapter = new NewsAdapter(getActivity(), articleArrayList);
        rvHeadline.setLayoutManager(new LinearLayoutManager(getActivity()));
        rvHeadline.setAdapter(newsAdapter);
        rvHeadline.setItemAnimator(new DefaultItemAnimator());
        rvHeadline.setNestedScrollingEnabled(true);
    } else {
        newsAdapter.notifyDataSetChanged();
    }
}
   }

好吧，我的錯誤在 pageViewModel.getNewsRepository() 內，如果我將泛型更改為結果類，我不知道該怎么辦，第一行中已修復錯誤，但第二行無法接受結果列表，我丟失了請幫助

視圖模型類

public class PageViewModel extends ViewModel {

private MutableLiveData<NewsResponse> mutableLiveData;
private NewsRepository newsRepository;

public void init(){
    if (mutableLiveData != null){
        return;
    }
    newsRepository = NewsRepository.getInstance();
    mutableLiveData = newsRepository.getNews( "***************");

}

public LiveData<NewsResponse> getNewsRepository() {
    return mutableLiveData;
}

  }

2 個解決方案

解決方案1
 0 已采納  2019-12-02 19:38:41

從您的ViewModel直接將NewsRepository的MutableLiveData給 View。

public class PageViewModel extends ViewModel {
    private NewsRepository newsRepository = NewsRepository.getInstance();

    public MutableLiveData<NewsResponse> getNewsRepository() {
        return newsRepository.getNews( "***************");
    }
}

目前您observe ViewModel 的MutableLiveData不發出任何值。 並且NewsRepository的MutableLiveData發出的數據在 ViewModel 中丟失，因為它沒有被觀察到。 您必須維護LiveData單個實例以觀察更改。

除此之外，您必須更新 Fragment 和 Adapter 以使用 List 而不是 List 因為您的json不包含文章列表。 它包含結果列表。 檢查下面

public class NewsFragment extends Fragment {


    ArrayList<Result> ArrayList = new ArrayList<>();

    ....


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        ....

        pageViewModel.getNewsRepository().observe(this, new Observer<NewsResponse>() {
            @Override
            public void onChanged(NewsResponse newsResponse) {
                articleArrayList = newsResponse.getResponse().getResults();
                newsAdapter.notifyDataSetChanged();
            }
        });

        ....

    }

    private void setupRecyclerView() {
        if (newsAdapter == null) {
            newsAdapter = new NewsAdapter(getActivity(), resultArrayList);
            rvHeadline.setLayoutManager(new LinearLayoutManager(getActivity()));
            rvHeadline.setAdapter(newsAdapter);
            rvHeadline.setItemAnimator(new DefaultItemAnimator());
            rvHeadline.setNestedScrollingEnabled(true);
        } else {
            newsAdapter.notifyDataSetChanged();
        }
    }

}

解決方案2
 0  2019-12-02 20:14:42

編輯

我將我的列表更改為結果

    ArrayList<Result> articleArrayList = new ArrayList<>();

另外我在這里改變了它

 @Override
        public void onChanged(NewsResponse newsResponse) {
            List<Result> newsArticles = newsResponse.getResponse().getResults();
            articleArrayList.addAll(newsArticles);

就像 Md.Asaduzzaman 說的，我也改變了適配器，一切正常

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