Question

我正在尝试使用片段来构建具有主和详细布局的应用程序，并且数据来自使用Asynctask消费webservice来解析JSOnArray。

无论我在各种论坛上针对类似问题的建议应用了哪些修补程序，我总是会看到来自logcat的错误：

FATAL EXCEPTION: main
    Process: com.example.masterdetail, PID: 26639
    java.lang.NullPointerException: println needs a message
            at android.util.Log.println_native(Native Method)
            at android.util.Log.d(Log.java:139)
            at com.example.masterdetail.ItemsListFragment.populateResult(ItemsListFragment.java:108) //this is the line where I am building an arraylist in ItemsListFragment.java
            at com.example.masterdetail.AsyncRequest.onPostExecute(AsyncRequest.java:147)
            at com.example.masterdetail.AsyncRequest.onPostExecute(AsyncRequest.java:23)
            at android.os.AsyncTask.finish(AsyncTask.java:632)
            at android.os.AsyncTask.access$600(AsyncTask.java:177)
            at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5001)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
            at dalvik.system.NativeStart.main(Native Method)

================== ItemsListFragment.java：

public void populateResult(String response) {
        /*TextView resultView = (TextView)getActivity().findViewById(R.id.textUrlContent);
        resultView.setText(response);*/
        try {
            ListView lvItems = (ListView) getActivity().findViewById(R.id.lvItems);
            ArrayList<Item> products = new ArrayList<Item>();
            JSONObject jsonObject = new JSONObject(response);
            JSONObject responseObj = jsonObject.getJSONObject("response");
            JSONArray jsonDataProducts = responseObj.getJSONArray("products");

            for (int i = 0; i < jsonDataProducts.length(); i++) {
                JSONObject oneObject = jsonDataProducts.getJSONObject(i);
                Item dataProduct = new Item();
                dataProduct.setTitle(oneObject.getString("title"));
                dataProduct.setBody(oneObject.getString("id"));
                products.add(dataProduct); //***Line: 108 from above error msg ************
            }

            adapterItems = new ArrayAdapter<Item>(getActivity(),
                    android.R.layout.simple_list_item_activated_1, products);
            lvItems.setAdapter(adapterItems);
            lvItems.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> adapterView, View item, int position,
                                        long rowId) {
                    // Retrieve item based on position
                    Item i = adapterItems.getItem(position);
                    // Fire selected event for item
                    listener.onItemSelected(i);
                }
            });
        } catch (Exception e) {
           Log.d("ReadRdaJSONFeedTask", e.getLocalizedMessage());
        }
    }

Answer 1

Log.d("ReadRdaJSONFeedTask", e.getLocalizedMessage());,

e.getlocalizedMessage()返回null。打电话前检查。

Log.d("ReadRdaJSONFeedTask", e.getLocalizedMessage() == null ? "" : e.getLocalizedMessage());

Android：NullPointerException：println需要一条消息;

1 个答案: