java - 类转换异常 [JSONArray 无法转换为 org.json.simple.JSONObject]

Question

我有一个像这样的 json 文件

[ {
    "id":"serve-coffee",
    "tags":[ {
        "name": "@tag1", "line": 1
    }
    ],
    "description":"Coffee should not be served\n",
    "name":"Serve coffee",
    "keyword":"Feature",
    "line":2,
    "elements":[ {
        "id": "serve-coffee;buy-last-coffee", "tags":[ {
            "name": "@tag2", "line": 6
        }
        ],
        "description":"",
        "name":"Buy last coffee",
        "keyword":"Scenario",
        "line":7,
        "steps":[ {
            "name": "there are 1 coffees left in the machine", "keyword": "Given ", "line": 8
        }
        ,
        {
            "name": "I have deposited 1$", "keyword": "And ", "line": 9
        }
        ],
        "type":"scenario"
    }
    ],
    "uri":"src\/test\/resources\/traffic-remove-locations.feature"
}

]

我正在尝试将上述 json 文件转换为 JSONObject .但是我遇到了类转换异常"java.lang.ClassCastException: org.json.simple.JSONArray cannot be cast to org.json.simple.JSONObject"

代码

public static JSONObject convertFileToJSON(String fileName) throws ParseException {

        // Read from File to String
        JSONParser parser = new JSONParser();
        JSONObject jsonObject = null;
        try {
            Object object = parser.parse(new FileReader(fileName));         
            jsonObject = (JSONObject) object;   // Getting classCast Exception here.

        } catch (FileNotFoundException e) {

        } catch (IOException ioe) {

        }       
        return jsonObject;
    }

but when i changed the line jsonObject = (JSONObject) object; to JSONArray jsonArray = (JSONObject)object异常消失。 但如果我转换到 JSONArray那么我怎样才能得到像id,tags这样的值和description来自JSONArray 。 请大家给点建议

Answer 1

您的 JSON 文件表示一个包含一个对象的数组。因此，如果这是一个 Java 数据结构，那么您实际上就是这样做的:

int[] arr = {5};
int i = (int)arr;

这显然不起作用，因为您无法将数组转换为单个对象。您真正想要做的是取出数组的第一个元素。要继续 Java 示例，您需要执行以下操作

int[] arr = {5};
int i = (int)arr[0];

对于 JSON 内容，您的 parser.parse() 调用返回 JSONArray，而不是 JSONObject。所以你需要做这样的事情:

public static JSONObject convertFileToJSON(String fileName) throws ParseException {
    JSONParser parser = new JSONParser();
    JSONObject jsonObject = null;
    try {
        JSONArray array = (JSONArray) parser.parse(new FileReader(fileName));         
        jsonObject = array.getJsonObject(0);

    } catch (FileNotFoundException e) {

    } catch (IOException ioe) {

    }       
    return jsonObject;
}