Android - 多級列表視圖

我對Android比較陌生，使用在線API。我有兩個活動。第一項活動是調出搜索結果列表並將它們放入ListView中。這不是問題。我試圖從此ListView中選擇一個項目，並將其傳遞給下一個活動，並使用所選項目的信息填充此新活動中的另一個ListView。這是問題所在。第二項活動永不加載。獲得第二個活動的好方法是什麼？我一直在做研究，沒有得到預期的結果。下面是兩個活動和助手類的代碼。謝謝Android - 多級列表視圖

的第一項活動

import helper.ArtistCalendarHelper; 

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

import org.w3c.dom.Document; 
import org.w3c.dom.Element; 
import org.w3c.dom.NodeList; 

import services.XMLParser; 

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.ListAdapter; 
import android.widget.ListView; 
import android.widget.SimpleAdapter; 
import android.widget.TextView; 
import android.widget.AdapterView.OnItemClickListener; 

public class ArtistsSearchActivity extends ListActivity { 

public static final String TAG = "ArtistsSearchActivity"; 
public static final String INTENT_EXTRAS_XML = "XML"; 

static final String KEY_ARTISTS = "artist"; 
static final String KEY_ID = "id"; 
static final String KEY_DISPLAY_NAME = "displayName"; 
static final String KEY_URI = "uri"; 
static final String KEY_ON_TOUR_UNTIL = "onTourUntil"; 
String onTourUntil ; 
String displayName; 
String identification; 

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_artists_search); 

    String xml = getIntent().getStringExtra(HomeActivity.INTENT_EXTRAS_XML); 

    List<HashMap<String, String>> menuItems = new ArrayList<HashMap<String, String>>(); 

    addArtistsToHashmap(menuItems, xml); 
    addItemsToList(menuItems); 
} 

private void addItemsToList(List<HashMap<String, String>> menuItems) { 
    ListAdapter adapter = new SimpleAdapter(this, menuItems, 
      R.layout.list_item_artist_search, new String[] { KEY_ID, KEY_DISPLAY_NAME, 
        KEY_URI, KEY_ON_TOUR_UNTIL }, new int[] { R.id.tvId, 
        R.id.tvDisplayName, R.id.tvUri, R.id.tvOnTourUntil }); 

    setListAdapter(adapter); 
} 

private void addArtistsToHashmap(List<HashMap<String, String>> menuItems, 
     String xml) { 
    XMLParser parser = new XMLParser(); 

    Document doc = parser.getDomElement(xml); 

    NodeList nl = doc.getElementsByTagName(KEY_ARTISTS); 
    for (int i = 0; i < nl.getLength(); i++) { 
     HashMap<String, String> map = new HashMap<String, String>(); 
     Element e = (Element) nl.item(i); 

     map.put(KEY_ID, e.getAttribute(KEY_ID)); 
     map.put(KEY_DISPLAY_NAME, e.getAttribute(KEY_DISPLAY_NAME)); 
     map.put(KEY_URI, e.getAttribute(KEY_URI)); 
     map.put(KEY_ON_TOUR_UNTIL, e.getAttribute(KEY_ON_TOUR_UNTIL)); 

     menuItems.add(map); 
    } 

// selecting single ListView item 
     ListView lv = getListView(); 

     lv.setOnItemClickListener(new OnItemClickListener() { 

      @Override 
      public void onItemClick(AdapterView<?> parent, View view, 
        int position, long id) { 
       // getting values from selected ListItem 
       displayName = ((TextView) view.findViewById(R.id.tvDisplayName)).getText().toString(); 
       onTourUntil = ((TextView) view.findViewById(R.id.tvOnTourUntil)).getText().toString(); 
       identification = ((TextView) view.findViewById(R.id.tvId)).getText().toString(); 

       new AsyncDownload().execute(identification); 
      } 
     }); 
} 

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

    ProgressDialog pDialog; 

    @Override 
    protected void onPreExecute() { 
     super.onPreExecute(); 
     pDialog = new ProgressDialog(ArtistsSearchActivity.this); 
     pDialog.setMessage("Please Wait..."); 

     pDialog.setCancelable(false); 
     pDialog.show(); 
    } 

    @Override 
    protected String doInBackground(String... params) { 

     Log.v(TAG, "query is" + params[0]); 
     String result = new ArtistCalendarHelper().getXml(params[0]); 
     return result; 
    } 

    @Override 
    protected void onCancelled() { 
     super.onCancelled(); 
     pDialog.dismiss(); 
    } 

    @Override 
    protected void onPostExecute(String result) { 
     super.onPostExecute(result); 
     pDialog.dismiss(); 
     Log.v(TAG, "result=" + result); 
     Intent intent = new Intent(); 
     intent.setClass(ArtistsSearchActivity.this, SingleArtistActivity.class); 
     intent.putExtra(KEY_DISPLAY_NAME, displayName); 
     intent.putExtra(KEY_ID, identification); 
     intent.putExtra(KEY_ON_TOUR_UNTIL, onTourUntil); 
     intent.putExtra(INTENT_EXTRAS_XML, result); 
     startActivity(intent); 
    } 
} 
}

第二個活動

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

import org.w3c.dom.Document; 
import org.w3c.dom.Element; 
import org.w3c.dom.NodeList; 

import services.XMLParser; 

import android.os.Bundle; 
import android.app.Activity; 
import android.app.ListActivity; 
import android.content.Intent; 
import android.widget.ListAdapter; 
import android.widget.SimpleAdapter; 
import android.widget.TextView; 


public class SingleArtistActivity extends ListActivity { 

public static final String TAG = "SingleArtistActivity"; 
public static final String INTENT_EXTRAS_XML = "XML"; 

static final String KEY_VENUE = "event"; 
static final String KEY_VENUE_NAME = "displayName"; 

    static final String KEY_DISPLAY_NAME = "displayName"; 
    static final String KEY_ON_TOUR_UNTIL = "onTourUntil"; 
    static final String KEY_ID = "id"; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_single_artist); 

     // getting intent data 
     Intent in = getIntent(); 

     // Get XML values from previous intent 
     String displayName = in.getStringExtra(KEY_DISPLAY_NAME); 
     String onTourUntil = in.getStringExtra(KEY_ON_TOUR_UNTIL); 
     String id = in.getStringExtra(KEY_ID); 

     // Displaying all values on the screen 
     TextView lblDisplayName = (TextView) findViewById(R.id.display_name_label); 
     TextView lblOnTourUntil = (TextView) findViewById(R.id.on_tour_until_label); 
     TextView lblID = (TextView) findViewById(R.id.id_label); 

     lblDisplayName.setText(displayName); 
     lblOnTourUntil.setText(onTourUntil); 
     lblID.setText(id); 

     String xml = getIntent().getStringExtra(HomeActivity.INTENT_EXTRAS_XML); 

     List<HashMap<String, String>> menuItems = new ArrayList<HashMap<String, String>>(); 


     addItemsToList(menuItems); 
     addCalendarToHashmap(menuItems, xml); 
    } 

    private void addItemsToList(List<HashMap<String, String>> menuItems) { 
     ListAdapter adapter = new SimpleAdapter(this, menuItems, 
       R.layout.list_item_artist_calendar, new String[] { KEY_VENUE_NAME }, new int[] { R.id.calendarDisplayName }); 

     setListAdapter(adapter); 
    } 

    private void addCalendarToHashmap(List<HashMap<String, String>> menuItems, 
      String xml) { 
     XMLParser parser = new XMLParser(); 

     Document doc = parser.getDomElement(xml); 

     NodeList nl = doc.getElementsByTagName(KEY_VENUE); 
     for (int i = 0; i < nl.getLength(); i++) { 
      HashMap<String, String> map = new HashMap<String, String>(); 
      Element e = (Element) nl.item(i); 

      map.put(KEY_VENUE_NAME, e.getAttribute(KEY_VENUE_NAME)); 

      menuItems.add(map); 
     } 
    } 
}

而且我的助手類

import java.io.BufferedReader; 
import java.io.IOException; 
import java.io.InputStream; 
import java.io.InputStreamReader; 
import java.io.UnsupportedEncodingException; 
import java.net.URLEncoder; 

import org.apache.http.HttpEntity; 
import org.apache.http.HttpResponse; 
import org.apache.http.client.HttpClient; 
import org.apache.http.client.methods.HttpGet; 
import org.apache.http.impl.client.DefaultHttpClient; 

import android.util.Log; 

public class LocationCalendarHelper { 
private static final String TAG = "LocationCalendarHelper"; 
private static final String SONGKICK_URL = "http://api.songkick.com/api/3.0/metro_areas/"; 
private static final String API_KEY = "yIekMi1hQzcFheKc"; 

public String getXml(String searchQuery) { 

    HttpClient httpclient = new DefaultHttpClient(); 

    String getParameters = ""; 
    try { 
     getParameters = URLEncoder.encode(searchQuery, "UTF-8") 
       + "/calendar.xml?apikey=" + URLEncoder.encode(API_KEY, "UTF-8"); 
    } catch (UnsupportedEncodingException e1) { 
     // TODO Auto-generated catch block 
     e1.printStackTrace(); 
    } 

    String url = SONGKICK_URL + getParameters; 
    // Prepare a request object 
    HttpGet httpget = new HttpGet(url); 

    // Execute the request 
    HttpResponse response; 
    try { 
     response = httpclient.execute(httpget); 
     // Examine the response status 
     Log.i(TAG, response.getStatusLine().toString()); 

     // Get hold of the response entity 
     HttpEntity entity = response.getEntity(); 
     // If the response does not enclose an entity, there is no need 
     // to worry about connection release 

     if (entity != null) { 

      // A Simple JSON Response Read 
      InputStream instream = entity.getContent(); 
      String result = convertStreamToString(instream); 

      // now you have the string representation of the HTML request 
      instream.close(); 
      return result; 
     } 

    } catch (Exception e) { 

     e.printStackTrace(); 
     return null; 
    } 
    return null; 
} 

private static String convertStreamToString(InputStream is) { 

    BufferedReader reader = new BufferedReader(new InputStreamReader(is)); 
    StringBuilder sb = new StringBuilder(); 

    String line = null; 
    try { 
     while ((line = reader.readLine()) != null) { 
      sb.append(line + "\n"); 
     } 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } finally { 
     try { 
      is.close(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } 
    } 
    return sb.toString(); 
} 

}

我的日誌貓錯誤。它從一堆xml開始，因此活動正在拉動信息，然後以錯誤結束

05-10 07:09:41.587: V/ArtistsSearchActivity(796):   <identifier mbid="eb558587-e7a1-4f2b-9fda-b6ff5e137ed1" href="http://api.songkick.com/api/3.0/artists/mbid:eb558587-e7a1-4f2b-9fda-b6ff5e137ed1.xml"/> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):   </artist> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):  </performance> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):  <performance billingIndex="3" displayName="Love And Death" billing="support" id="32720419"> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):   <artist displayName="Love And Death" uri="http://www.songkick.com/artists/286472-love-and-death?utm_source=19089&amp;utm_medium=partner" id="286472"> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):   <identifier mbid="27796970-8f7a-4196-9f7d-87f091af4412" href="http://api.songkick.com/api/3.0/artists/mbid:27796970-8f7a-4196-9f7d-87f091af4412.xml"/> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):   <identifier mbid="c29b667e-9895-41d2-b5a5-1817050ce0bc" href="http://api.songkick.com/api/3.0/artists/mbid:c29b667e-9895-41d2-b5a5-1817050ce0bc.xml"/> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):   </artist> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):  </performance> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):  <venue displayName="Rostraver Ice Garden Arena" lat="40.1981235" lng="-79.8294916" uri="http://www.songkick.com/venues/51599-rostraver-ice-garden-arena?utm_source=19089&amp;utm_medium=partner" id="51599"> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):   <metroArea displayName="Belle Vernon" uri="http://www.songkick.com/metro_areas/56020-us-belle-vernon?utm_source=19089&amp;utm_medium=partner" id="56020"> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):   <state displayName="PA"/> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):   <country displayName="US"/> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):   </metroArea> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):  </venue> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):  <start time="19:30:00" datetime="2013-05-15T19:30:00-0500" date="2013-05-15"/> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):  <location lat="40.1981235" lng="-79.8294916" city="Belle Vernon, PA, US"/> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):  </event> 
05-10 07:09:41.587: V/ArtistsSearchActivity(796):  <event type="Festival" status="ok" displayName="Rock on the Range 2013" uri="http://www.songkick.com/festivals/8261/id/14745014-rock-on-the-range-2013?utm_source=19089&amp;utm_medium=partner" popularity="0 
05-10 07:09:41.637: I/Choreographer(796): Skipped 49 frames! The application may be doing too much work on its main thread. 
05-10 07:09:43.807: E/Trace(871): error opening trace file: No such file or directory (2) 
05-10 07:09:45.357: E/Trace(910): error opening trace file: No such file or directory (2) 
05-10 07:09:45.687: E/Trace(923): error opening trace file: No such file or directory (2) 
05-10 07:09:46.307: E/Trace(936): error opening trace file: No such file or directory (2) 
05-10 07:09:47.167: E/Trace(949): error opening trace file: No such file or directory (2) 
05-10 07:09:48.337: E/Trace(975): error opening trace file: No such file or directory (2)

我有更新。上面的代碼工作！我會把它留給那些需要它的人。我遇到的問題是，如果xml字符串太長，搜索超時。那麼，我該如何讓Android有更多時間來進行搜索呢？

來源

2013-05-10 user2305700

private void addItemsToList(List<HashMap<String, String>> menuItems) { 
     ListAdapter adapter = new SimpleAdapter(this, menuItems, 
      R.layout.list_item_artist_calendar, new String[] { KEY_VENUE_NAME }, new int[] { R.id.calendarDisplayName }); 

     setListAdapter(adapter); 
     adapter.notifyDataSetChanged(); 


    }

來源

2013-05-10 05:36:16

忘記調用adapter.notifyDatasetChange（）。添加ItemsToList並調用addCalendarToHashmap（menuItems，xml）;然後addItemsToList（menuItems）;在onCreate（） – 2013-05-10 05:39:26

謝謝，我收到一個錯誤，說明類型ListAdapter的notifyDatasetChange（）未定義。有沒有應該使用的演員？ – user2305700 2013-05-10 06:17:04

use adapter.notifyDataSetChanged（）; – 2013-05-10 06:27:45

Android - 多級列表視圖

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