android - JSON 解析在 Java 中无法按预期工作

Question

我之前做过 JSON 解析，但这个对我不起作用。我不知道为什么。这是一个非常简单的结构，我仍然无法修复它。

这是我从我的 URL 获得的响应。

{
    "BalanceItems" : [{
            "BalanceItem" : {
                "BalanceType" : "General Cash",
                "Description" : "Prepay Credit",
                "ShortDescription" : "Your bal is $",
                "Value" : 187.95,
                "Unit" : "$NZ",
                "ExpiryValue" : "",
                "ExpiryDate" : "18\/02\/2012"
            }
        }, {
            "BalanceItem" : {
                "BalanceType" : "Me 2 U",
                "Description" : "Me2U Credit",
                "ShortDescription" : "Your bal is $",
                "Value" : 176.86,
                "Unit" : "$NZ",
                "ExpiryValue" : "176.86",
                "ExpiryDate" : "12\/06\/2011"
            }
        }, {
            "BalanceItem" : {
                "BalanceType" : "Rate Plan Recharge Reward",
                "Description" : "Your 'top up and get' special rates",
                "ShortDescription" : "Your 'top up and get' rates are yours until",
                "Value" : ""
            }
        }
    ]
}

这是我的代码

try{

            URL url = new URL("myurl");         
            URLConnection connection = url.openConnection();   

            String line;   
            StringBuilder builder = new StringBuilder();   
            BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream())); 

           while((line = reader.readLine()) != null) {    
               builder.append(line);   
           }   

           String response = builder.toString();   

           JSONObject jar = new JSONObject(response);
           Log.e("Object Size","Object Size  "+ jar.length());
           // Here i should get the size of object as 3 because i have three object of type "BalanceItem"

        }
        catch (Exception e) {
            // TODO: handle exception
        }

Answer 1

您有一个包含 JSONArray 的 JSON 对象。您需要获取 JSONArray:

JSONArray array = jar.getJSONArray("BalanceItems");
Log.e("Object Size","array Size  "+ array.length());

在此处检查 API:

http://www.json.org/javadoc/org/json/JSONObject.html#getJSONArray%28java.lang.String%29

http://www.json.org/javadoc/org/json/JSONArray.html

---

附录:

数组依次包含多个 JSONObject。您需要遍历它并获取每一个:

for (int i=0; i<array.length(); i++) {
  JSONObject obj = array.getJSONObject(i);
  Log.d ("Balance "+i, obj.getString("Value") + " " + obj.getString("Unit")); 
}

你明白了。在我的头顶上输入这里，所以要小心打字错误。