android - 无法将 JSON 解析的数据加载到 ArrayList 中并显示在 ListView 上

Question

我正在尝试解析以下 JSON 数据以将书的作者和标题存储到 ListView 中:

{
    "kind": "books#volumes",
    "totalItems": 921,
    "items": [{
                "kind": "books#volume",
                "id": "QP7VvnhDOOsC",
                "etag": "BQzzyT9zza0",
                "selfLink": "https://www.googleapis.com/books/v1/volumes/QP7VvnhDOOsC",
                "volumeInfo": {
                    "title": "Programming Android",
                    "authors": ["Zigurd Mednieks", "Laird Dornin", "G. Blake Meike", "Masumi Nakamura"],
                    "publisher": "\"O'Reilly Media, Inc.\"",
                    "publishedDate": "2012",
                    "description": "Presents instructions for creating Android applications for mobile devices using Java.",
                    "industryIdentifiers": [{
                        "type": "ISBN_13",
                        "identifier": "9781449316648"
                    }, {
                        "type": "ISBN_10",
                        "identifier": "1449316646"
                    }],
                    "readingModes": {
                        "text": false,
                        "image": true
                    },
                    "pageCount": 542,
                    "printType": "BOOK",
                    "categories": ["Computers"],
                    "averageRating": 3.5,
                    "ratingsCount": 6,
                    "maturityRating": "NOT_MATURE",
                    "allowAnonLogging": false,
                    "contentVersion": "preview-1.0.0",
                    "imageLinks": {
                        "smallThumbnail": "http://books.google.co.in/books/content?id=QP7VvnhDOOsC&printsec=frontcover&img=1&zoom=5&edge=curl&source=gbs_api",
                        "thumbnail": "http://books.google.co.in/books/content?id=QP7VvnhDOOsC&printsec=frontcover&img=1&zoom=1&edge=curl&source=gbs_api"
                    },
                    "language": "en",
                    "previewLink": "http://books.google.co.in/books?id=QP7VvnhDOOsC&printsec=frontcover&dq=android+intitle&hl=&cd=1&source=gbs_api",
                    "infoLink": "http://books.google.co.in/books?id=QP7VvnhDOOsC&dq=android+intitle&hl=&source=gbs_api",
                    "canonicalVolumeLink": "http://books.google.co.in/books/about/Programming_Android.html?hl=&id=QP7VvnhDOOsC"
                },
                "saleInfo": {
                    "country": "IN",
                    "saleability": "NOT_FOR_SALE",
                    "isEbook": false
                },
                "accessInfo": {
                    "country": "IN",
                    "viewability": "PARTIAL",
                    "embeddable": true,
                    "publicDomain": false,
                    "textToSpeechPermission": "ALLOWED",
                    "epub": {
                        "isAvailable": false
                    },
                    "pdf": {
                        "isAvailable": false
                    },
                    "webReaderLink": "http://books.google.co.in/books/reader?id=QP7VvnhDOOsC&hl=&printsec=frontcover&output=reader&source=gbs_api",
                    "accessViewStatus": "SAMPLE",
                    "quoteSharingAllowed": false
                },
                "searchInfo": {
                    "textSnippet": "Presents instructions for creating Android applications for mobile devices using Java."
                }
            }, {
                "kind": "books#volume",
                "id": "S1QQ-mOaPd8C",
                "etag": "hbStdCg087k",
                "selfLink": "https://www.googleapis.com/books/v1/volumes/S1QQ-mOaPd8C",
                "volumeInfo": {
                    "title": "Sams Teach Yourself Java in 21 Days (Covering Java 7 and Android)",
                    "authors": ["Rogers Cadenhead"],  

以下是我用于 JSON 解析并将数据添加到 ArrayList 的方法。

public void DisplayList(String result) {
    try {
        JSONObject jsonobject = new JSONObject(result);
        JSONArray jarray = jsonobject.getJSONArray("items");

        for (int i = 0; i < jarray.length(); i++) {
            JSONObject volumeInfo = jarray.getJSONObject(i).getJSONObject("volumeInfo");
            String book_title = volumeInfo.getString("title");
            JSONArray authors = volumeInfo.getJSONArray("authors");
            for (int j = 0; j < authors.length(); j++) {
                String book_author = authors.getString(i);
                books.add(new Book(book_title, book_author));
            }
        }
    } catch (JSONException e) {
        e.printStackTrace();
    }

    BooksAdapter adapter = new BooksAdapter(this, books);
    ListView listView = (ListView) findViewById(R.id.list);

    listView.setAdapter(adapter);

    //listView.setVisibility((adapter.isEmpty())?View.GONE:View.VISIBLE);
    if (adapter.isEmpty()) {
        defaultTextView.setText(no_response_message[2]);
        //"No data to display, please enter correct keyword and search again."

    }
} 

当我使用函数 books.add() 时，它运行完美，但是当我尝试显示 ListView 时，我弹出 ListView 空消息。

可能是什么错误导致我无法将数据存储到 ArrayList 中。

Answer 1

首先JSON String没有正常关闭，应该是:

{"kind":"books#volumes","totalItems":921,"items":[{"kind":"books#volume","id":"QP7VvnhDOOsC","etag":"BQzzyT9zza0","selfLink":"https://www.googleapis.com/books/v1/volumes/QP7VvnhDOOsC","volumeInfo":{"title":"Programming Android","authors":["Zigurd Mednieks","Laird Dornin","G. Blake Meike","Masumi Nakamura"],"publisher":"\"O'Reilly Media, Inc.\"","publishedDate":"2012","description":"Presents instructions for creating Android applications for mobile devices using Java.","industryIdentifiers":[{"type":"ISBN_13","identifier":"9781449316648"},{"type":"ISBN_10","identifier":"1449316646"}],"readingModes":{"text":false,"image":true},"pageCount":542,"printType":"BOOK","categories":["Computers"],"averageRating":3.5,"ratingsCount":6,"maturityRating":"NOT_MATURE","allowAnonLogging":false,"contentVersion":"preview-1.0.0","imageLinks":{"smallThumbnail":"http://books.google.co.in/books/content?id=QP7VvnhDOOsC&printsec=frontcover&img=1&zoom=5&edge=curl&source=gbs_api","thumbnail":"http://books.google.co.in/books/content?id=QP7VvnhDOOsC&printsec=frontcover&img=1&zoom=1&edge=curl&source=gbs_api"},"language":"en","previewLink":"http://books.google.co.in/books?id=QP7VvnhDOOsC&printsec=frontcover&dq=android+intitle&hl=&cd=1&source=gbs_api","infoLink":"http://books.google.co.in/books?id=QP7VvnhDOOsC&dq=android+intitle&hl=&source=gbs_api","canonicalVolumeLink":"http://books.google.co.in/books/about/Programming_Android.html?hl=&id=QP7VvnhDOOsC"},"saleInfo":{"country":"IN","saleability":"NOT_FOR_SALE","isEbook":false},"accessInfo":{"country":"IN","viewability":"PARTIAL","embeddable":true,"publicDomain":false,"textToSpeechPermission":"ALLOWED","epub":{"isAvailable":false},"pdf":{"isAvailable":false},"webReaderLink":"http://books.google.co.in/books/reader?id=QP7VvnhDOOsC&hl=&printsec=frontcover&output=reader&source=gbs_api","accessViewStatus":"SAMPLE","quoteSharingAllowed":false},"searchInfo":{"textSnippet":"Presents instructions for creating Android applications for mobile devices using Java."}},{"kind":"books#volume","id":"S1QQ-mOaPd8C","etag":"hbStdCg087k","selfLink":"https://www.googleapis.com/books/v1/volumes/S1QQ-mOaPd8C","volumeInfo":{"title":"Sams Teach Yourself Java in 21 Days (Covering Java 7 and Android)","authors":["Rogers Cadenhead"]}}]}

---

现在，你的解析函数正确地完成了它的工作，你只是在你的嵌套 for 中有一个小错误，它应该是 authors.getString(j) 而不是 authors.getString(i )。 for 循环最终会是:

for (int i = 0; i < jarray.length(); i++) {
    JSONObject volumeInfo = jarray.getJSONObject(i).getJSONObject("volumeInfo");
    String book_title = volumeInfo.getString("title");
    JSONArray authors = volumeInfo.getJSONArray("authors");
    for (int j = 0; j < authors.length(); j++) {
        String book_author = authors.getString(j);
        books.add(new Book(book_title, book_author));
    }
}

---

无论如何，您应该仍会在 ListView 中显示一些内容，所以我猜您的适配器代码或 Book 类中还有另一个错误。