Question

我正在创建一个listview，用于加载数据库中的名称。 CustomerID用于访问名称的详细信息视图。我在Android Studio VDM中获得输出没有任何问题。但是当我在手机上运行它（Android 4.3）时，会出现以下错误。

java.lang.NullPointerException：尝试在com.tut.app.GetAllCustomerListViewAdapter.getCount（GetAllCustomerListViewAdapter.java:38）的空对象引用上调用虚方法'int org.json.JSONArray.length（）'

我的主要活动：

public class MainActivity extends ActionBarActivity {

    private ListView GetAllCustomerListView;
    private JSONArray jsonArray;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        this.GetAllCustomerListView = (ListView) this.findViewById(R.id.GetAllCustomerListView);

        new GetAllCustomerTask().execute(new ApiConnector());

        this.GetAllCustomerListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                try
                {
                    // GEt the customer which was clicked
                    JSONObject customerClicked = jsonArray.getJSONObject(position);

                    // Send Customer ID
                    Intent showDetails = new Intent(getApplicationContext(),CustomerDetailsActivity.class);
                    showDetails.putExtra("CustomerID", customerClicked.getInt("id"));

                    startActivity(showDetails);

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

    }



    public  void setListAdapter(JSONArray jsonArray)
    {
        this.jsonArray = jsonArray;
        this.GetAllCustomerListView.setAdapter(new GetAllCustomerListViewAdapter(jsonArray,this));
    }




    private class GetAllCustomerTask extends AsyncTask<ApiConnector,Long,JSONArray>
    {
        @Override
        protected JSONArray doInBackground(ApiConnector... params) {

            // it is executed on Background thread

             return params[0].GetAllCustomers();
        }

        @Override
        protected void onPostExecute(JSONArray jsonArray) {

            setListAdapter(jsonArray);


        }
    }

}

请帮忙！：（

Answer 1

我发现什么是错的！：d 我的笔记本电脑已连接到Localhost。因此，它在运行应用程序时没有任何问题。但只有当我在服务器中托管php文件和数据库时，该应用程序在手机中完美无缺！希望这有助于某人！

数据库连接在Android Studio VDM中运行良好，但在手机中运行良好

1 个答案: