從JSONArray Android中

Question

提取值我有此JSON對象

{ 
"kind": "books#volumes", 
"totalItems": 482, 
"items": [ 
    { 
    "kind": "books#volume", 
    "id": "MoXpe6H2B5gC", 
    "etag": "6dr4Ka3Iksc", 
    "selfLink": "https://www.googleapis.com/books/v1/volumes/MoXpe6H2B5gC", 
    "volumeInfo": { 
    "title": "Android in The Attic", 
    "authors": [ 
    "Nicholas Allan" 
    ], 
    "publisher": "Hachette UK", 
    "publishedDate": "2013-01-03", 
    "description": "Aunt Edna has created a no-nonsense nanny android to make sure Billy and Alfie don't have any fun. But then Alfie discovers how to override Auntie Anne-Droid's programming and nothing can stop them eating all the Cheeki Choko Cherry Cakes they like ... until the real aunt Edna is kidnapped!", 

我要提取3個鍵「標題」，「作者」，通過該代碼片段「描述」：

JSONObject baseJsonResponse = new JSONObject(bookJSON); 

     // Extract the JSONArray associated with the key called "features", 
     // which represents a list of features (or books). 
     JSONArray bookArray = baseJsonResponse.getJSONArray("items"); 

     // For each book in the bookArray, create an {@link book} object 
     for (int i = 0; i < bookArray.length(); i++) { 

      // Get a single book at position i within the list of books 
      JSONObject currentBook = bookArray.getJSONObject(i); 

      // For a given book, extract the JSONObject associated with the 
      // key called "volumeInfo", which represents a list of all volumeInfo 
      // for that book. 
      JSONObject volumeInfo = currentBook.getJSONObject("volumeInfo"); 

      // Extract the value for the key called "title" 
      String title = volumeInfo.getString("title"); 

      // Extract the value for the key called "authors" 
      String authors = volumeInfo.getString("author"); 

      // Extract the value for the key called "description" 
      String description = volumeInfo.getString("description"); 

「標題」和「描述」工作正常，但作者部分沒有。正如我所看到的，「作者」實際上是一個JSONArray，所以我在屏幕上的輸出是

["Nicholas Allan"] 

這不是我所期望的。所以，我想這個代碼

JSONArray author = volumeInfo.getJSONArray("authors"); 
       String authors = author.get(0); 

改變我的做法，並提取元素，但Android Studio中說get（）方法的輸入必須是一個字符串。 我是JSON和Android的新手，所以我從來沒有見過沒有像這樣的值的JSON密鑰。任何人都可以告訴我如何從JSONArray中提取元素？

Answer 1

由於get()方法返回一個對象，你需要將它轉換爲一個字符串：

String authors = (String) author.get(0); 

或者，你可以使用JSONArray的getString(index)方法，其中0是該指數。

JSONArray author = volumeInfo.getJSONArray("authors"); 
String authors = author.getString(0);