java - 构造函数 SimpleAdapter 未定义

Question

我正在开发一个应用程序，可以在 reomte 数据库上进行查询，使用 Json 和 PHP 通过 MySQL 稍后将结束 posgress，因为它更加开放。

我的问题是，我的 SimpleAdapter 被 Eclipse 认为是未定义的，没有任何快速修复，奇怪的是，在我尝试使用输入示例时添加按钮之前，一切都工作正常。因此，我不知道如何修复这个错误。

代码是:

import java.util.ArrayList;
import java.util.HashMap;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;

public class DataconectActivity extends ListActivity {
    EditText  searcher;
    Button btmsearch; 
    // adding strings that are going to be the tags of the nodes for the list view in the ListAdapter
    private static String TAG_PRODID = "codigo";
    private static final String TAG_NOMBRE = "nombre";
    private static final String TAG_DESCRIPCION = "descripcion";
    private static final String TAG_COLOR = "color";
    private static final String TAG_PESO =  "peso";
    private static final String TAG_PRECIO = "precio";
    private static final String TAG_DISPONIBILIDAD = "disponibilidad";
    private static final String TAG_INFO = "resultados";
    // remember to change the url to try it with the web server http://trialsols.webege.com/mobil.php after this is important to add at least 10.000 items to the db to ensure the query efficiency
    private static final String url ="http://192.168.1.50/mobilv1.php";
    ArrayList<HashMap<String, String>> jsonResultList = new ArrayList<HashMap<String, String>>();
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);



        searcher = (EditText) findViewById(R.id.searchtxt);
        btmsearch = (Button) findViewById(R.id.searchbtm);

        btmsearch.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub


                // Hashmap for ListView

                String data = searcher.getText().toString()   ;

                ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
                nameValuePairs.add(new BasicNameValuePair("precio",data));

                // Creating JSON Parser instance
                JsonParser jParser = new JsonParser();

                // getting JSON string from URL
                JSONArray jArray = jParser.getJSONFromUrl(nameValuePairs, url);


                try {

                    // looping through All JsonData 
                    for(int i = 0; i < jArray.length() ; i++){
                        JSONObject json_data = jArray.getJSONObject(i);
                        String nombre = json_data.getString("nombre");
                        String prodid = json_data.getString("prodid");
                        String descripcion = json_data.getString("descripcion");
                        String color = json_data.getString("color");
                        String peso = json_data.getString("peso");
                        String precio = json_data.getString("precio");
                        String disponibilidad = json_data.getString("disponibilidad");  
                        // creating new HashMap
                        HashMap<String, String> map = new HashMap<String, String>();

                        // adding each child node to HashMap key => value
                        map.put(TAG_PRODID, prodid);
                        map.put(TAG_NOMBRE, nombre);
                        map.put(TAG_DESCRIPCION, descripcion);
                        map.put(TAG_COLOR, color);
                        map.put(TAG_PESO, peso);
                        map.put(TAG_PRECIO, precio);
                        map.put(TAG_DISPONIBILIDAD, disponibilidad);
                        // adding HashList to ArrayList
                        jsonResultList.add(map);

                    }
                }

                catch(JSONException e){
                    Log.e("log_tag", "Error parsing data "+e.toString());
                }                

                //adding the results of the parsed JSON data to a listView using a ListAdapter
                ListAdapter adapter = new SimpleAdapter(this, jsonResultList,
                        R.layout.datalistitems,
                        new String[] { TAG_NOMBRE, TAG_PRECIO, TAG_DISPONIBILIDAD }, new int[] {
                        R.id.dbnombretxt, R.id.dbpreciotxt, R.id.dbdisponibilidadtxt });

                // add in a ListActivity We need to make
                setListAdapter(adapter);    
                // initialize a ListView to display the single item information
                ListView lv = getListView();
                lv.setTextFilterEnabled(true);
                //  generate the action when an item is clicked
                lv.setOnItemClickListener(new OnItemClickListener() {
                    public void onItemClick(AdapterView<?> parent, View view,
                            int position, long id) {
                        // When clicked, create a view with the values
                        // getting values from selected ListItem
                        String name = ((TextView) view.findViewById(R.id.dbnombretxt)).getText().toString();
                        String cost = ((TextView) view.findViewById(R.id.dbpreciotxt)).getText().toString();
                        String stock = ((TextView) view.findViewById(R.id.dbdisponibilidadtxt)).getText().toString();

                        // Starting new intent
                        Intent in = new Intent(getApplicationContext(), SearchResults.class);
                        in.putExtra(TAG_NOMBRE, name);
                        in.putExtra(TAG_PRECIO, cost);
                        in.putExtra(TAG_DISPONIBILIDAD, stock);
                        startActivity(in);
                    }
                });

            }

        });

    }

} 

错误确实出现:

adapter = new SimpleAdapter(this, jsonResultList,
                        R.layout.datalistitems,
                        new String[] { TAG_NOMBRE, TAG_PRECIO, TAG_DISPONIBILIDAD }, new int[] {
                        R.id.dbnombretxt, R.id.dbpreciotxt, R.id.dbdisponibilidadtxt });

Answer 1

您正在 View.OnClickListener 内部构建 SimpleAdapter 实例，因此您对 this 的引用指向 OnClickListener，这不是有效的上下文。您将需要像这样修改您的代码行:

adapter = new SimpleAdapter(DataconectActivity.this, jsonResultList,
                    R.layout.datalistitems,
                    new String[] { TAG_NOMBRE, TAG_PRECIO, TAG_DISPONIBILIDAD }, new int[] {
                    R.id.dbnombretxt, R.id.dbpreciotxt, R.id.dbdisponibilidadtxt });

这将为您的构造函数提供正确的引用。

HTH