在JSON数组

Question

我知道有重复的问题。尽管如此，我无法弄清楚这一点。

以下是我从API收到的JSON文件。我需要得到＃34;年＆＃34;值。

我得到的错误是：

  

message org.glassfish.jersey.server.ContainerException：org.json.JSONException：找不到JSONArray [1]。

与Java上的这一行有关：

JSONObject year = years.getJSONObject(1).getJSONObject("years");

我也尝试过：

JSONObject year = years.getJSONObject(1);

为什么这段代码不起作用？ index 1数组中是否year明确years？

JSON

{
    "make": {
        "id": 200000404,
        "name": "Chevrolet",
        "niceName": "chevrolet"
    },
    "model": {
        "id": "Chevrolet_Camaro",
        "name": "Camaro",
        "niceName": "camaro"
    },
    "drivenWheels": "rear wheel drive",
    "numOfDoors": "2",
    "options": [],
    "colors": [],
    "manufacturerCode": "1EH67",
    "price": {
        "baseMSRP": 34180.0,
        "baseInvoice": 32813.0,
        "deliveryCharges": 900.0,
        "usedTmvRetail": 17766.0,
        "usedPrivateParty": 16321.0,
        "usedTradeIn": 14755.0,
        "estimateTmv": false,
        "tmvRecommendedRating": 0
    },
    "categories": {
        "market": "Performance",
        "EPAClass": "Compact Cars",
        "vehicleSize": "Midsize",
        "primaryBodyType": "Car",
        "vehicleStyle": "Convertible",
        "vehicleType": "Car"
    },
    "vin": "2G1FC3D33C9165616",
    "squishVin": "2G1FC3D3C9",
    "years": [{
        "id": 100531911,
        "year": 2012,
        "styles": [{
            "id": 101395591,
            "name": "LT 2dr Convertible w/2LT (3.6L 6cyl 6M)",
            "submodel": {
                "body": "Convertible",
                "modelName": "Camaro Convertible",
                "niceName": "convertible"
            },
            "trim": "LT"
        }]
    }],
    "matchingType": "SQUISHVIN",
    "MPG": {
        "highway": "28",
        "city": "17"
    }
}

JAVA

    public String vehicleData(@PathParam("vin") String vin,
                               @PathParam("key") String key) throws Exception {

        GetVehicleJSON jsonData = new GetVehicleJSON(vin, key);
        JSONObject data = jsonData.getVehicleData();

        String name = data.getJSONObject("make").getString("name"); 

        String highway = data.getJSONObject("MPG").getString("highway");
        String city = data.getJSONObject("MPG").getString("city");

        JSONArray years = data.getJSONArray("years");
        JSONObject year = years.getJSONObject(1).getJSONObject("years");
        String s = year.getString("year");

        return name + " " + s + " " + highway + " " + city;
    }

Answer 1

您正在使用索引从零开始的JSON数组。这样做：

   JSONArray years = data.getJSONArray("years");

   String year = years.getJSONObject(0).getString("year");

Answer 2

你的json显示年份值是一个包含1个元素的数组，并且该元素内部是一个对象：

"years": [{ "id": 100531911, "year": 2012, "styles": [{ "id": 101395591, "name": "LT 2dr Convertible w/2LT (3.6L 6cyl 6M)", "submodel": { "body": "Convertible", "modelName": "Camaro Convertible", "niceName": "convertible" }, "trim": "LT" }] }],

因为数组元素编号从0开始，这意味着如果选择元素1，您将收到此错误：

  

message org.glassfish.jersey.server.ContainerException：org.json.JSONException：找不到JSONArray [1]。

要修复它，您需要选择元素0而不是1：

years.getJSONObject(0);