RSS應用程序，與我的ListView有問題

Question

好吧，所以我想在android中使用ListView製作一個RSS應用程序。我有2個類讀取html並返回包含標題，描述和鏈接的對象數組。

public class RSS 
{ 
    public static NewsStory[] readRSS(String urlAddress) 
    { 
     try{ 
      NewsStory[] stories = new NewsStory[10]; 
      URL rssUrl = new URL(urlAddress); 
      BufferedReader in = new BufferedReader(new InputStreamReader(rssUrl.openStream())); 
      String rawString; 
      String item = ""; 
      int i = 0; 
      while((rawString = in.readLine()) != null) 
      { 
       if(rawString.contains("<item>")) 
       { 

        int titleEndIndex = 0; 
        int titleStartIndex = 0; 
        while (titleStartIndex >= 0 && i < 10) 
        { 
         titleStartIndex = rawString.indexOf("<item>", titleEndIndex); 
         if (titleStartIndex >= 0) 
         { 
          titleEndIndex = rawString.indexOf("</item>", titleStartIndex); 
          item = rawString.substring(titleStartIndex + "<item>".length(), titleEndIndex) + "\n"; 
         } 
         stories[i] = new NewsStory(getContent(item,"title"),getContent(item,"description"),getContent(item,"link")); 
         i++; 
        } 
        in.close(); 
        return stories; 
       } 
      } 
     } 
     catch(MalformedURLException ue) 
     { 
      System.out.print("Malformed URL"); 
     } 
     catch(IOException ioe) 
     { 
      System.out.print("Something went wrong reading the contents"); 
     } 
     return null; 
    } 

    public static String getContent(String item, String target) 
    { 
     String excerpt = ""; 
     int titleEndIndex = 0; 
     int titleStartIndex = 0; 
     while (titleStartIndex >= 0) { 
      titleStartIndex = item.indexOf("<"+target+">", titleEndIndex); 
      if (titleStartIndex >= 0) { 
       if (target.equals("description")) 
        titleEndIndex = item.indexOf("&", titleStartIndex); 
       else 
        titleEndIndex = item.indexOf("</"+target+">", titleStartIndex); 
       excerpt += item.substring(titleStartIndex + ("<"+target+">").length(), titleEndIndex) + "\n"; 

      } 
      return excerpt; 
     } 
     return "error"; 
    } 
} 

和

public class NewsStory { 

    String title; 
    String description; 
    String link; 


    public NewsStory() 
    { 
     this.title = ""; 
     this.description = ""; 
     this.link = ""; 
    } 
    public NewsStory(String title, String description, String link) { 
     this.title = title; 
     this.description = description; 
     this.link = link; 
    } 

    public String getTitle() { 
     return title; 
    } 

    public void setTitle(String title) { 
     this.title = title; 
    } 

    public String getDescription() { 
     return description; 
    } 

    public void setDescription(String description) { 
     this.description = description; 
    } 

    public String getLink() { 
     return link; 
    } 

    public void setLink(String link) { 
     this.link = link; 
    } 

} 

我在Java中測試的Java類，和它們很好地工作，則返回用含有標題，描述，和連桿10點的故事的陣列。我的問題是，我需要現在填充我的android應用程序中的數據字段使用ListView。我無法將信息連接到ListView。我嘗試了一個適配器，但我不太瞭解適配器。任何指針將不勝感激。

，我試圖在它的片段是這樣的

public class HeadlineFragment extends Fragment { 

    EditText input; 
    Button search; 
    ListView headlines; 
    private NewsDataSource ds; 
    private ListView newsListView; 

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

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     // Inflate the layout for this fragment 
     View v = inflater.inflate(R.layout.fragment_headline,container,false); 
     ds = new NewsDataSource(); 
     newsListView = (ListView)v.findViewById(R.id.listView); 
     //newsListView.setAdapter(new NewsDataSourceAdapter()); 

     input = (EditText)v.findViewById(R.id.txtInput); 
     search = (Button)v.findViewById(R.id.btnSearch); 
     headlines = (ListView)v.findViewById(R.id.listView); 

     return v; 
    } 

} 

Answer 1

如果你使用一個ListView，你需要一個適配器。適配器位於您的ListView和您的數據之間。

您需要創建一個從Adapter繼承的新Adapter類。在它的構造函數中，你傳遞你的NewsStory數組。然後，在getView（）中，您將創建ListView行佈局，並將NewsStory對應的所有數據填入該位置。

這是適配器的基本功能。您可以瞭解更多信息並查看示例here。

一旦你瞭解了Adapters的工作方式，我強烈建議你將ListView切換到RecyclerView並開始使用ViewHolder模式，這極大地幫助了列表的性能和RAM的使用。