Question

我正在使用扩展AsyncTask的类，但我在执行类

的行中有错误

我无法弄清楚

这是包含我的主类和扩展AsyncTask

的类的类

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import com.example.androidhive.library.JSONParser;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;

                public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.topics_list);

            // Hashmap for ListView
            TopicsList = new ArrayList<HashMap<String, String>>();

            **// Loading products in Background Thread
            new LoadAllTopics().execute();**

            // Get listview
            ListView lv = getListView();

            // on seleting single product
            // launching Edit Product Screen
            lv.setOnItemClickListener(new OnItemClickListener() {

                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                // getting values from selected ListItem
                String tid = ((TextView) view.findViewById(R.id.tid)).getText()
                    .toString();




            /**
            * Background Async Task to Load all product by making HTTP Request
            * */
            class LoadAllTopics extends AsyncTask<String, String, String> {

            /**
             * Before starting background thread Show Progress Dialog
             * */
            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                pDialog = new ProgressDialog(Topics_list.this);
                pDialog.setMessage("Loading products. Please wait...");
                pDialog.setIndeterminate(false);
                pDialog.setCancelable(false);
                pDialog.show();
            }

            /**
             * getting All products from url
             * */
            protected String doInBackground(String... args) {
                // Building Parameters
                List<NameValuePair> params = new ArrayList<NameValuePair>();
                // getting JSON string from URL
                JSONObject json = jParser.makeHttpRequest (url_all_topics, "GET", params);

                // Check your log cat for JSON reponse
                Log.d("All topics: ", json.toString());

                try {
                // Checking for SUCCESS TAG
                int success = json.getInt(TAG_SUCCESS);

                if (success == 1) {
                    // products found
                    // Getting Array of Products
                    topics = json.getJSONArray(TAG_TOPICS);

                    // looping through All Products
                    for (int i = 0; i < topics.length(); i++) {
                    JSONObject c = topics.getJSONObject(i);

                    // Storing each json item in variable
                    String id = c.getString(TAG_TOPICSID);
                    String topict = c.getString(TAG_TOPICTITLE);
                    String username = c.getString(TAG_TOPICAUTHOR);

                    // creating new HashMap
                    HashMap<String, String> map = new HashMap<String, String>();

                    // adding each child node to HashMap key => value
                    map.put(TAG_TOPICSID, id);
                    map.put(TAG_TOPICTITLE, topict);
                    map.put(TAG_TOPICAUTHOR, username);

                    // adding HashList to ArrayList
                    TopicsList.add(map);
                    }
                } else {
                    // no products found
                    // Launch Add New product Activity
                   /* Intent i = new Intent(getApplicationContext(),
                        NewProductActivity.class);
                    // Closing all previous activities
                    i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                    startActivity(i);*/
                }
                } catch (JSONException e) {
                e.printStackTrace();
                }

                return null;
            }

            /**
             * After completing background task Dismiss the progress dialog
             * **/
            protected void onPostExecute(String file_url) {
                // dismiss the dialog after getting all products
                pDialog.dismiss();
                // updating UI from Background Thread
                runOnUiThread(new Runnable() {
                public void run() {
                    /**
                     * Updating parsed JSON data into ListView
                     * */
                    ListAdapter adapter = new SimpleAdapter(
                       Topics_list.this, TopicsList,
                        R.layout.list_item, new String[] { TAG_TOPICSID,TAG_TOPICTITLE,
                            TAG_TOPICAUTHOR},
                        new int[] { R.id.tid, R.id.name });
                    // updating listview
                    setListAdapter(adapter);
                }
                });

            }

            }
            } });}}

错误是粗线

非常感谢您的帮助

Answer 1

在Java中，您需要在类中编写方法。将onCreate放在Class。

中

public class MainActivity extends Activity {
   public void onCreate(Bundle savedInstanceState) {
           .....
         lv.setOnItemClickListener(new OnItemClickListener() {

            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            // getting values from selected ListItem
            String tid = ((TextView) view.findViewById(R.id.tid)).getText()
                .toString();
            }
         });
          .........
   }

   private class LoadAllTopics extends AsyncTask<String, String, String> {

        .....
   }
}

调用类的错误扩展了asynctask来运行它

1 个答案: