將Pojo轉換成Gson

我有一個問題，將pojo轉換爲gson，我的轉換方法凍結了應用程序，然後顯示一個對話框，顯示「應用程序未響應，是否要關閉它？」將Pojo轉換成Gson

下面是POJO類

NewsTrend.class

public class NewsTrend extends RealmObject { 

     private String title; 
     private String href; 
     private String content; 
     private String image; 
     private String timestamp; 
     private Integer comments; 
     private String type; 
     private String flag; 
     private String ext_date; 
     private Integer like_status; 
     private Integer like_count; 
     private Integer read_count; 
     private Integer dislike_count; 
     private Integer read_status; 
     private Integer news_id; 


     /* Requires an empty constructor */ 
     public NewsTrend() { 
     } 

     public NewsTrend(NewsTrend postsData) { 
      this.title = postsData.getTitle(); 
      this.href = postsData.getHref(); 
      this.timestamp = postsData.getTimestamp(); 
      this.type = postsData.getType(); 
      this.comments = postsData.getComments(); 
      this.image = postsData.getImage(); 
      this.content = postsData.getContent(); 
      this.flag = postsData.getFlag(); 
      this.ext_date = postsData.getExt_date(); 
      this.like_status = postsData.getLike_status(); 
      this.like_count = postsData.getLike_count(); 
      this.dislike_count = postsData.getDislike_count(); 
      this.read_status = postsData.getRead_status(); 
      this.news_id = postsData.getNews_id(); 
      this.read_count = postsData.getRead_count(); 
     } 


     public String getTitle() { 
      return title; 
     } 

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

     public String getHref() { 
      return href; 
     } 

     public void setHref(String href) { 
      this.href = href; 
     } 

     public String getContent() { 
      return content; 
     } 

     public void setContent(String content) { 
      this.content = content; 
     } 

     public String getImage() { 
      return image; 
     } 

     public void setImage(String image) { 
      this.image = image; 
     } 

     public String getTimestamp() { 
      return timestamp; 
     } 

     public void setTimestamp(String timestamp) { 
      this.timestamp = timestamp; 
     } 

     public Integer getComments() { 
      return comments; 
     } 

     public void setComments(Integer comments) { 
      this.comments = comments; 
     } 

     public String getType() { 
      return type; 
     } 

     public void setType(String type) { 
      this.type = type; 
     } 

     public String getFlag() { 
      return flag; 
     } 

     public void setFlag(String flag) { 
      this.flag = flag; 
     } 

     public String getExt_date() { 
      return ext_date; 
     } 

     public void setExt_date(String ext_date) { 
      this.ext_date = ext_date; 
     } 

     public Integer getLike_status() { 
      return like_status; 
     } 

     public void setLike_status(Integer like_status) { 
      this.like_status = like_status; 
     } 

     public Integer getLike_count() { 
      return like_count; 
     } 

     public void setLike_count(Integer like_count) { 
      this.like_count = like_count; 
     } 

     public Integer getRead_count() { 
      return read_count; 
     } 

     public void setRead_count(Integer read_count) { 
      this.read_count = read_count; 
     } 

     public Integer getDislike_count() { 
      return dislike_count; 
     } 

     public void setDislike_count(Integer dislike_count) { 
      this.dislike_count = dislike_count; 
     } 

     public Integer getRead_status() { 
      return read_status; 
     } 

     public void setRead_status(Integer read_status) { 
      this.read_status = read_status; 
     } 

     public Integer getNews_id() { 
      return news_id; 
     } 

     public void setNews_id(Integer news_id) { 
      this.news_id = news_id; 
     } 
    }

NewsTrendList.class

public class NewsTrendList extends RealmObject { 

     private RealmList<NewsTrend> data; 

     /** 
     * 
     * @return 
     *  The data 
     */ 
     public RealmList<NewsTrend> getData() { 
      return data; 
     } 

     /** 
     * 
     * @param data 
     *  The data 
     */ 
     public void setData(RealmList<NewsTrend> data) { 
      this.data = data; 
     } 
    }

下面是轉換方法

public static String convertToJson(ArrayList<NewsTrend> newsItems) { 
      Gson gson = new Gson(); 
      String json = gson.toJson(newsItems); //The App hangs on this line 

      return json; 
     }

以下是使用轉換的完整類。

public class Utils { 

//public RealmResults<NewsTrend> realmResults; 

public static boolean isNewsLikedOrFaved(Context context, NewsTrend newsItem, boolean isLiked) { 

    ArrayList<NewsTrend> newsItems = getLikedOrFavedNews(context, isLiked); 

    if (newsItems != null) { 


     for (NewsTrend news : newsItems) { 

      if (newsItem.getNews_id().equals(news.getNews_id())) { 
       Log.d("logFavourite", "isNewsLikedOrFaved true newsItem.getId: " + newsItem.getNews_id() + ", news.getId: " + news.getNews_id()); 

       return true; 
      } 
     } 
    } 

    Log.d("logFavourite", "isNewsLikedOrFaved false"); 

    return false; 

} 


public static void likeOrFavNews(Context context, NewsTrend newsItem, boolean isLike) { 

    Log.d("logFavourite", "likeNews"); 


    SharedPreferences preferences = context.getSharedPreferences("Prefs", Context.MODE_PRIVATE); 

    String jsonLikedNews; 
    if (isLike) 
     jsonLikedNews = preferences.getString("likedNews", null); 
    else 
     jsonLikedNews = preferences.getString("favedNews", null); 


    if (jsonLikedNews != null) { 
     ArrayList<NewsTrend> newsItems = convertToModel(jsonLikedNews); 
     newsItems.add(newsItem); 

     Log.d("logFavourite", "size: " + newsItems.size()); 
     String jsonUpdatedLikedNews = convertToJson(newsItems); 

     SharedPreferences.Editor editor = preferences.edit(); 
     if (isLike) 
      editor.putString("likedNews", jsonUpdatedLikedNews); 
     else 
      editor.putString("favedNews", jsonUpdatedLikedNews); 

     editor.commit(); 
    } else { 

     ArrayList<NewsTrend> newsItems = new ArrayList<>(); 
     newsItems.add(newsItem); 

     Log.d("logFavourite", "size: " + newsItems.size()); 
     String jsonUpdatedLikedNews = convertToJson(newsItems); 


     SharedPreferences.Editor editor = preferences.edit(); 
     if (isLike) 
      editor.putString("likedNews", jsonUpdatedLikedNews); 
     else 
      editor.putString("favedNews", jsonUpdatedLikedNews); 

     editor.commit(); 


    } 

} 

public static void unlikeOrUnfavNews(Context context, NewsTrend newsItem, boolean isLike) { 

    Log.d("logFavourite", "likeNews"); 

    SharedPreferences preferences = context.getSharedPreferences("Prefs", Context.MODE_PRIVATE); 

    String jsonLikedNews; 
    if (isLike) 
     jsonLikedNews = preferences.getString("likedNews", null); 
    else 
     jsonLikedNews = preferences.getString("favedNews", null); 

    if (jsonLikedNews != null) { 
     ArrayList<NewsTrend> newsItems = convertToModel(jsonLikedNews); 

     for (int i = 0; i < newsItems.size(); i++) { 

      if (newsItems.get(i).getNews_id() == newsItem.getNews_id()) 
       newsItems.remove(i); 

     } 

     Log.d("logFavourite", "size: " + newsItems.size()); 


     String jsonUpdatedLikedNews = convertToJson(newsItems); 

     SharedPreferences.Editor editor = preferences.edit(); 
     if (isLike) 
      editor.putString("likedNews", jsonUpdatedLikedNews); 
     else 
      editor.putString("favedNews", jsonUpdatedLikedNews); 

     editor.commit(); 
    } 

} 

public static ArrayList<NewsTrend> getLikedOrFavedNews(Context context, boolean isLike) { 

    SharedPreferences preferences = context.getSharedPreferences("Prefs", Context.MODE_PRIVATE); 
    String jsonLikedNews; 
    if (isLike) 
     jsonLikedNews = preferences.getString("likedNews", null); 
    else 
     jsonLikedNews = preferences.getString("favedNews", null); 

    ArrayList<NewsTrend> newsItems; 
    if (jsonLikedNews != null) { 
     newsItems = convertToModel(jsonLikedNews); 
    } else { 
     newsItems = new ArrayList<>(); 
    } 
    return newsItems; 


} 

     public static String convertToJson(ArrayList<NewsTrend> newsItems) { 
      Gson gson = new Gson(); 
      Log.d("erroFav", "some better error" + newsItems.toString()); 
      String json = gson.toJson(newsItems); 

      return json; 
     } 

public static ArrayList<NewsTrend> convertToModel(String jsonString) { 
    Gson gson = new Gson(); 
    NewsTrend[] newsItems = gson.fromJson(jsonString, NewsTrend[].class); 
    ArrayList<NewsTrend> newsItemList = new ArrayList<>(); 

    for (int i = 0; i < newsItems.length; i++) { 
     newsItemList.add(newsItems[i]); 
    } 
    return newsItemList; 
} 





public static String convertToNewsJson(NewsTrend news) { 
    Gson gson = new Gson(); 
    String json = gson.toJson(news); 
    return json; 
} 

public static NewsTrend convertToNewsModel(String jsonString) { 
    Gson gson = new Gson(); 
    NewsTrend news = gson.fromJson(jsonString, NewsTrend.class); 
    return news; 
}

}

來源

2016-07-16 SimpiMind

因爲你正在創建一個實例new Gson()每一次你轉換JSON元素成一個對象，而不必僅僅一個 GSON實例。

這也可能是你實際上沒有在後臺線程上進行解析，如果你使用Volley，這是一個常見的錯誤。如果你直接創建你寫給共享偏好的巨大String對象，爲什麼你甚至在你的應用中有Realm？避免使用實際的數據庫？你不應該有一個String在內存中，如果數據集太大）。

來源

2016-07-16 15:00:48 EpicPandaForce

似乎你很好地理解了這個問題，希望你能指導我解決這個問題，有沒有我應該更改或提供部分代碼，以便可以解決。謝謝。 – SimpiMind

我正在使用改造，試圖在我的應用程序中創建一個類似而不同的功能，您使用Shared Preference的原因。 – SimpiMind

你應該在你的Application子類中創建一個** Gson的實例，然後在任何地方或者在'Utils'類中使用private static final Gson gson = new Gson（）;'。您應該使用Realm通過查詢來獲得您喜歡的和最喜歡的新聞，並且您應該完全離開SharedPreferences。 – EpicPandaForce

U可以轉換使用POJO http://www.jsonschema2pojo.org/ 網站GSON。

來源

2016-07-16 14:54:46 Lovekesh

這不是我想要做的，我已經將我的json轉換爲pojo – SimpiMind

將Pojo轉換成Gson

回答

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