Question

我从另一个函数获取一个JSON字符串并将其转换为JSONObject，以便将这些字符串值存储到单独的变量中。然后我将JSONObject中的变量发送到另一个类。你可以在logcat中看到，我成功地将JSON字符串添加到我的函数中，我认为错误是将JSON分成单独的变量。有人可以帮帮我吗？我是android中的菜鸟

04-16 08:02:03.170: D/js string(1865): {"create_time":"2015-04-16T08:01:51Z","id":"PAY-5LH931619M647525PKUXWY3Y","intent":"sale","state":"approved"}
04-16 08:02:03.170: D/DoInBackground(1865): {"create_time":"2015-04-16T08:01:51Z","id":"PAY-5LH931619M647525PKUXWY3Y","intent":"sale","state":"approved"}
04-16 08:02:03.171: W/System.err(1865): org.json.JSONException: No value for 
04-16 08:02:03.172: W/System.err(1865):     at org.json.JSONObject.get(JSONObject.java:389)
04-16 08:02:03.173: W/System.err(1865):     at org.json.JSONObject.getJSONObject(JSONObject.java:609)
04-16 08:02:03.173: W/System.err(1865):     at learn2crack.listview.Donate$ProcessPayment.doInBackground(Donate.java:228)
04-16 08:02:03.173: W/System.err(1865):     at learn2crack.listview.Donate$ProcessPayment.doInBackground(Donate.java:1)
04-16 08:02:03.173: W/System.err(1865):     at android.os.AsyncTask$2.call(AsyncTask.java:288)
04-16 08:02:03.173: W/System.err(1865):     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
04-16 08:02:03.174: W/System.err(1865):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
04-16 08:02:03.174: W/System.err(1865):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
04-16 08:02:03.174: W/System.err(1865):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
04-16 08:02:03.174: W/System.err(1865):     at java.lang.Thread.run(Thread.java:818)
04-16 08:02:03.299: E/AndroidRuntime(1865): FATAL EXCEPTION: AsyncTask #1
04-16 08:02:03.299: E/AndroidRuntime(1865): Process: learn2crack.listview, PID: 1865
04-16 08:02:03.299: E/AndroidRuntime(1865): java.lang.RuntimeException: An error occured while executing doInBackground()
04-16 08:02:03.299: E/AndroidRuntime(1865):     at android.os.AsyncTask$3.done(AsyncTask.java:300)
04-16 08:02:03.299: E/AndroidRuntime(1865):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
04-16 08:02:03.299: E/AndroidRuntime(1865):     at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
04-16 08:02:03.299: E/AndroidRuntime(1865):     at java.util.concurrent.FutureTask.run(FutureTask.java:242)
04-16 08:02:03.299: E/AndroidRuntime(1865):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
04-16 08:02:03.299: E/AndroidRuntime(1865):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
04-16 08:02:03.299: E/AndroidRuntime(1865):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
04-16 08:02:03.299: E/AndroidRuntime(1865):     at java.lang.Thread.run(Thread.java:818)
04-16 08:02:03.299: E/AndroidRuntime(1865): Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String org.json.JSONObject.getString(java.lang.String)' on a null object reference
04-16 08:02:03.299: E/AndroidRuntime(1865):     at learn2crack.listview.Donate$ProcessPayment.doInBackground(Donate.java:240)
04-16 08:02:03.299: E/AndroidRuntime(1865):     at learn2crack.listview.Donate$ProcessPayment.doInBackground(Donate.java:1)
04-16 08:02:03.299: E/AndroidRuntime(1865):     at android.os.AsyncTask$2.call(AsyncTask.java:288)
04-16 08:02:03.299: E/AndroidRuntime(1865):     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
04-16 08:02:03.299: E/AndroidRuntime(1865):     ... 4 more

Java代码：

protected JSONObject doInBackground(String... args) {

        UserFunctions userFunction = new UserFunctions();
        String js = args[0];
        Log.d("js string", js);
        JSONObject obj;
        JSONObject ii=null;
        try {
            obj = new JSONObject(js);
            Log.d("DoInBackground", obj.toString());
            ii = obj.getJSONObject("");
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        //JSONObject sendjson=null;

        String create_time="";
        String id="";
        String intent="";
        String sale=""; 
        try {
            create_time = ii.getString("create_time");
            id = ii.getString("id");
            intent = ii.getString("intent");
            sale = ii.getString("sale");
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        Log.d("strings", create_time + "," + id + "," + intent + "," +sale);
        JSONObject sendjson = userFunction.CreatePayment(create_time, id, intent,
                sale);
        Log.d("sendjson", sendjson.toString());

        return sendjson;


    }

Answer 1

问题是由此行引起的

 ii = obj.getJSONObject("");

您没有JSONObject映射到空键字符串。您正在寻找的密钥已经可以通过JSONObject obj; E.g

进行检索

  create_time = obj.getString("create_time");

您也可以使用optString代替getString。主要区别在于optString不会产生异常，但会返回默认值（null表示字符串）

Answer 2

你不需要行ii = obj.getJSONObject("")，obj = new JSONObject(js)已经是你的全部JSONObject。只需删除所有ii引用（和JSONObject）并替换为obj

create_time = obj.getString("create_time");
id = obj.getString("id");
intent = obj.getString("intent");
sale = obj.getString("sale");

Answer 3

你不需要ii！当您撰写ii = obj.getJSONObject("");时，它将返回null，因为没有空密钥。这没有意义。

此外，您尝试访问ii.getString，但如果有JSONException，则ii为null！

试试这个：

protected JSONObject doInBackground(String... args) {
    UserFunctions userFunction = new UserFunctions();
    String js = args[0];
    Log.d("js string", js);
    JSONObject obj;
    String create_time="";
    String id="";
    String intent="";
    String sale=""; 
    JSONObject sendjson;
    try {
        obj = new JSONObject(js);
        Log.d("DoInBackground", obj.toString());
        //HERE obj is not null ! 
        try {
            create_time = obj.getString("create_time");
            id = obj.getString("id");
            intent = obj.getString("intent");
            sale = obj.getString("sale");
            Log.d("strings", create_time + "," + id + "," + intent + "," +sale);
            sendjson = userFunction.CreatePayment(create_time, id, intent, sale);
            Log.d("sendjson", sendjson.toString());
        } catch (JSONException e) {
            e.printStackTrace();
        }

    } catch (JSONException e) {
        e.printStackTrace();
    }
    //check when you use this function that sendjson is not null !
    return sendjson;
}

将JSONObject存储到变量中并将它们发送到另一个函数

3 个答案: