如何获取其中包含多个 JSONObject 的数据

Posted 2023-04-19

【中文标题】如何获取其中包含多个 JSONObject 的数据

【英文标题】：How to fetch the data which has multiple JSONObject in it

【发布时间】：2021-09-08 12:40:05

【问题描述】：

这是我必须获取的 JSON 响应：

  "markets": [
    
      "exchange_id": "BINANCE",
      "symbol": "BTC-USDT",
      "price_unconverted": 37193.095,
      "price": 37228.28172528144,
      "change_24h": -4.547427178236877,
      "spread": 0.000026886707486166165,
      "volume_24h": 3422591459.036938,
      "status": "recent",
      "time": "2021-06-04T22:41:01"
    ,
    
      "exchange_id": "BINANCE",
      "symbol": "ETH-USDT",
      "price_unconverted": 2734.6549999999997,
      "price": 2737.2421349029846,
      "change_24h": -3.7432242168250704,
      "spread": 0.0003656761718006455,
      "volume_24h": 3244286756.710182,
      "status": "recent",
      "time": "2021-06-04T22:41:01"
    ,
    ...
  ],
  "pagination": 
    "next": "10"
  

我已经为第一个 JSON 对象编写了代码，其中包含数组列表。 我想知道如何在我的代码中获取第二个 JSON 对象，以便获取整个 JSON 对象值。

我的代码 ->

val queue = Volley.newRequestQueue(this) val url = "https://www.cryptingup.com/api/markets"

val jsonObjectRequest = object : JsonObjectRequest(Method.GET, url, null,
    Response.Listener 

        try 

        val markets = it.getJSONArray("markets")
        for (i in 0 until markets.length()) 

            val marketJsonObject = markets.getJSONObject(i)
            val marketObject = Market(
                marketJsonObject.getString("exchange_id"),
                marketJsonObject.getString("symbol"),
                marketJsonObject.getString("price_unconverted"),
                marketJsonObject.getString("price"),
                marketJsonObject.getString("change_24th"),
                marketJsonObject.getString("spread"),
                marketJsonObject.getString("volume_24th"),
                marketJsonObject.getString("status"),
                marketJsonObject.getString("time")

            )
           marketList.add(marketObject)
            
                recyclerAdapter =
                    MarketRecyclerAdapter(this, marketList)

                recyclerMarket.adapter = recyclerAdapter

                recyclerMarket.layoutManager = layoutManager

        
         catch (e: JSONException) 
            Toast.makeText(this, "$it JSON error Occured", Toast.LENGTH_LONG).show()
        

    , Response.ErrorListener 

        Toast.makeText(this, "Volley Error Occured $it", Toast.LENGTH_LONG).show()

    )

    override fun getHeaders(): MutableMap<String, String> 
        val headers = HashMap<String, String>()
        headers["Content-type"] = "application/json"

        return headers
    


queue.add(jsonObjectRequest)

【问题讨论】：

将“recycler”代码移到for 循环之外，即在marketList 填满所有对象之前不要调用MarketRecyclerAdapter(...)。

【参考方案1】：

试试下面的代码，它会对你有所帮助。

     try 
       
        val marketsArray: JSONArray = it.getJSONArray("markets")
        for (countItem in 0 until marketsArray.length()) 
            val returnObject = marketsArray.getJSONObject(countItem)
            val exchangeId =
                if (returnObject.isNull("exchange_id")) "" else returnObject.optString("exchange_id")
            val symbol =
                if (returnObject.isNull("symbol")) "" else returnObject.optString("symbol")
        
        val pagination: JSONObject = it.getJSONObject("pagination")
        val next = pagination.getString("next")
     catch (e: JSONException) 
        e.printStackTrace()
    

【参考方案2】：

另一方面，您是否尝试过使用 kotlinx 序列化将 JSON 对象（转换为字符串）映射到 POJO？

https://kotlinlang.org/docs/serialization.html https://github.com/Kotlin/kotlinx.serialization