java - TFL 开放数据的 JSON 解析

Question

大家好，我正在尝试从这个 LINK 解析一个 JSON 文件.

返回的JSON如下-

我需要遍历 journeys 的所有实例 首先，然后我必须遍历 legs 对于每个 journeys 获取 detailed 指令。如您所见，每个 legs 由 instruction 组成 部分返回 string ，我的最终目标是结合这些 string 为每个旅程并将它们显示为 TextView 。所以对于上面的 JSON，最终目标是显示 -

Jubilee line towards Stratford, or North Greenwich

Northern line towards Edgware, or High Barnet

到目前为止，我一直在尝试浏览这个 JSON 没有任何运气。

这是我一直在处理的代码-

try {
       //object is the JSON file.
       JSONArray Journey = object.getJSONArray("journeys");
       if (Journey != null) {
        //Retrieving number of possible routes.
        for (int i=0;i<Journey.length();i++){
             Routes.add(Journey.getJSONObject(i));
        }
        //Retrieving number of possible legs for each route.
        if (!Routes.isEmpty()){
        for (int j = 0; j< Routes.size(); j++){
             Legs.add(j, Routes.get(j).getJSONArray("legs"));
        }
        //Trying to retrieve the detailed instruction here and failing.
        for(int k=0;k<Routes.get(k).getJSONArray("legs").length();k++){
            instructionDetail.add(k,Legs.get(k).getJSONObject(k).getJSONObject("instruction"));
          
        }
     }
 }

} catch (JSONException e) {
                    e.printStackTrace();
              }

我认为我的方法是错误的，我没有得到正确的循环。非常感谢解析和导航以及任何其他方法的建议!

谢谢!

更新:

Answer 1

JSONArray journeys = new JSONObject("");
        for(int i = 0 ; i < journeys.length() ; i++) { // Traverse journeys
            JSONObject journey = journeys.getJSONObject(i); // get journeys(i) -> journey
            if(journey.has("legs")) { // if journey has "legs" key
                JSONArray legs = journey.getJSONArray("legs"); // get the legs array from journey object
                for(int j = 0 ; j < legs.length() ; j++) { // Traverse legs
                    JSONObject leg = legs.getJSONObject(j); // get legs(j) -> leg
                    if(leg.has("instruction")) { // if leg has "instruction" key in it 
                        JSONObject instruction = leg.getJSONObject("instruction"); // get instruction jsonObject
                        String detailed = instruction.optString("detailed", "Fallback detailed"); // get detailed string in instruction object
                    }
                }
            }
        }

更新:

private static class Detail {
        String journeyType;
        String legType;
        String instructionType;
        String detail;

        public Detail(String journeyType, String legType, String instructionType, String detail) {
            this.journeyType = journeyType;
            this.legType = legType;
            this.instructionType = instructionType;
            this.detail = detail;
        }
    }

......

List<Detail> detailList = new ArrayList<>();
        JSONArray journeys = new JSONObject("");
        for(int i = 0 ; i < journeys.length() ; i++) { // Traverse journeys
            JSONObject journey = journeys.getJSONObject(i); // get journeys(i) -> journey
            if(journey.has("legs")) { // if journey has "legs" key
                JSONArray legs = journey.getJSONArray("legs"); // get the legs array from journey object
                for(int j = 0 ; j < legs.length() ; j++) { // Traverse legs
                    JSONObject leg = legs.getJSONObject(j); // get legs(j) -> leg
                    if(leg.has("instruction")) { // if leg has "instruction" key in it
                        JSONObject instruction = leg.getJSONObject("instruction"); // get instruction jsonObject
                        String journeyType = journey.getString("$type");
                        String legType = leg.getString("$type");
                        String instructionType = instruction.getString("$type");
                        String detailed = instruction.getString("detailed"); // get detailed string in instruction object
                        detailList.add(new Detail(journeyType, legType, instructionType, detailed));
                    }
                }
            }
        }
        for(Detail detail : detailList) {
            TextView textView = new TextView([yourContext]);
            textView.setText(detail.detail);
            yourContentViewGroup.addView(textView);
            // or you can use View.inflate(context, layoutRes, yourContentViewGroup) and design a layout to show other detail instance values
        }