如何在java中从列表中获取Jsonobject

Question

我有两个jsonobject在列表中。如果我创建新的 jsonobject 并尝试获取列表，它会给我 null。

代码如下-

    private int isExisting(String pid, List profile, String size) throws JSONException {
       for (int i = 0; i < profile.size(); i++) {
           JSONObject obj = new JSONObject(profile.get(i));
           log.info("--------------" + obj.toString());   //it is giving me an empty object but list contains two objects {"size":"M","id":11} and {"size":8,"id":19}
       }
    }

Answer 1

我试过这个它有效

private void isExisting(String pid, List profile, String size) throws JSONException {
    for (int i = 0; i < profile.size(); i++) {
        if(profile.get(i)!=null) {
            JSONObject obj = new JSONObject(profile.get(i).toString());
            System.out.print("keys----------" + obj.toString());  
        }
    }
}
public void processList() {
    try {
        JSONObject objA= new JSONObject("{n" +
                "      "size": "M",n" +
                "      "id": 11n" +
                "    }");
        JSONObject objB=new JSONObject("{n" +
                "      "size": 8,n" +
                "      "id": 19n" +
                "    }");
        List<JSONObject> list=new ArrayList<>();
        list.add(objA);
        list.add(objB);
        isExisting("",list,"");
    } catch (JSONException e) {
        e.printStackTrace();
    }
}

Answer 2

我已经尝试了这个简单的逻辑，它工作正常-

private int isExisting(String pid, List profile, String size) throws JSONException {
       for (int i = 0; i < profile.size(); i++) {
           JSONObject obj = (JSONObject) profile.get(i);
           log.info("--------------" + obj.toString());   
       }
    }