我有一个类SomeActivity扩展了BaseListActivity。 BaseListActivity扩展了ListActivity，所有这些都有效。
但是当列表必须更新时，我使用AsyncTask进行远程服务器调用，声明如下：
public class DownloadWebPageTask extends AsyncTask<String, Void, String>
在那里，有一行来更新列表，如下所示：
adapter.notifyDataSetChanged();
但这条线似乎没有做任何事情。
知道应该有什么不同才能让它发挥作用吗？
这是BaseListActivity
public class BaseListActivity extends ListActivity {
public ListView getListView() {
return (ListView)findViewById(android.R.id.list);
}
public ListAdapter getListAdapter() {
return getListView().getAdapter();
}
@Override
public void setContentView(int layoutResID) {
super.setContentView(layoutResID);
{
setListAdapter(this.getListAdapter());
Button home_header = (Button) findViewById(R.id.home_header);
Button questions_header = (Button) findViewById(R.id.questions_header);
home_header.setOnClickListener(new Button.OnClickListener() {
public void onClick(View v) {
Intent myIntent = new Intent(BaseListActivity.this,
ProblemioActivity.class);
BaseListActivity.this.startActivity(myIntent);
}
});
questions_header.setOnClickListener(new Button.OnClickListener() {
public void onClick(View v) {
Intent myIntent = new Intent(BaseListActivity.this,
MyQuestionsActivity.class);
BaseListActivity.this.startActivity(myIntent);
}
});
}
}
}
这是整个DownloadWebPageTask代码：
public class DownloadWebPageTask扩展了AsyncTask
{
@覆盖
protected String doInBackground（String ... theParams）
{
字符串myUrl = theParams [0];
final String user_id = theParams [1];
String charset = "UTF-8";
String response = null;
try
{
String query = String.format("user_id=%s",
URLEncoder.encode( user_id, charset) );
final URL url = new URL( myUrl + "?" + query );
Log.d( "QuestionUserURL" , url+ "" );
final HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setDoOutput(true);
conn.setRequestMethod("POST");
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.connect();
final InputStream is = conn.getInputStream();
final byte[] buffer = new byte[8196];
int readCount;
final StringBuilder builder = new StringBuilder();
while ((readCount = is.read(buffer)) > -1)
{
builder.append(new String(buffer, 0, readCount));
}
response = builder.toString();
}
catch (Exception e)
{
Log.d( "EXCEPTIONNNN: " , "Yup" + e.getMessage());
e.printStackTrace();
}
Log.d( "MyQuestionsActivity" , "*** Response: " + response );
return response;
}
@Override
protected void onPostExecute(String result)
{
Log.d( "MyQuestionsActivity" , "In the post-execute method: " + result );
if ( result != null && result.trim().equals( "no_user_id" ) )
{
Log.d( "Post execute: " , "NOOOT OKKKK - no user id" );
// Show the user a message that they did not enter the right login
Toast.makeText(getApplicationContext(), "Could not get your questions. We are working to fix this. ", Toast.LENGTH_LONG).show();
sendEmail("Error in My Questions", "The questions by user did not load because on the server the validation for user id said the user id was empty." );
}
else
if ( result != null && result.trim().equals( "database_error" ) )
{
Log.d( "Post execute: " , "NOOOT OKKKK - no user database error" );
// Show the user a message that they did not enter the right login
Toast.makeText(getApplicationContext(), "Could not get your questions. We are working to fix this. ", Toast.LENGTH_LONG).show();
sendEmail("Error in My Questions", "The questions by user did not load because on the server there " +
"was a database error." );
}
else
if ( result != null && result.trim().equals( "no_questions_by_user" ) )
{
// Show the user a message that they did not enter the right login
//Toast.makeText(getApplicationContext(), "You have not asked any questions. Ask your business questions! ", Toast.LENGTH_LONG).show();
//sendEmail("No Questions so far in My Questions", "User got message that they do not have questions." );
TextView question_label = (TextView) findViewById(R.id.question_label);
question_label.setText("You have not asked any business questions. Ask your question." );
}
else
{
Log.d( "MyQuestionsActivity" , "In JSON parsing area.." );
try
{
JSONArray obj = new JSONArray(result);
if ( obj != null )
{
questions.clear();
for ( int i = 0; i < obj.length(); i++ )
{
JSONObject o = obj.getJSONObject(i);
String question_id = o.getString("question_id");
String question = o.getString("question");
String questioner_id = o.getString("member_id");
String first_name = o.getString("first_name");
String last_name = o.getString("last_name");
Log.d( "Question: " , question );
Log.d( "Question_id: " , question_id );
Question q = new Question ( );
q.setQuestion(question);
q.setQuestionId(question_id);
q.setQuestionByMemberId( questioner_id );
q.setAuthorName(first_name + " " + last_name );
questions.add( q );
}
}
adapter.notifyDataSetChanged();
TextView question_label = (TextView) findViewById(R.id.question_label);
question_label.setText("The questions you asked are below. Choose one or ask a new question.");
}
catch ( Exception e )
{
Log.d( "MyQuestionsActivity: " , "some crap happened 1: " + e.getMessage() );
e.printStackTrace();
}
}
//adapter.notifyDataSetChanged();
}
}
这是我现在在日志中看到的例外：
05-26 19:59:55.774: W/System.err(3103): java.net.UnknownHostException: Unable to resolve host "www.problemio.com": No address associated with hostname
05-26 19:59:55.777: W/System.err(3103): at java.net.InetAddress.lookupHostByName(InetAddress.java:426)
05-26 19:59:55.777: W/System.err(3103): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)
05-26 19:59:55.777: W/System.err(3103): at java.net.InetAddress.getAllByName(InetAddress.java:220)
05-26 19:59:55.777: W/System.err(3103): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:71)
05-26 19:59:55.777: W/System.err(3103): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
05-26 19:59:55.777: W/System.err(3103): at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:351)
05-26 19:59:55.777: W/System.err(3103): at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:86)
05-26 19:59:55.777: W/System.err(3103): at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
05-26 19:59:55.777: W/System.err(3103): at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:308)
05-26 19:59:55.777: W/System.err(3103): at libcore.net.http.HttpEngine.connect(HttpEngine.java:303)
05-26 19:59:55.777: W/System.err(3103): at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:282)
05-26 19:59:55.777: W/System.err(3103): at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:232)
05-26 19:59:55.797: W/System.err(3103): at libcore.net.http.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:80)
05-26 19:59:55.807: W/System.err(3103): at utils.SendEmail.doInBackground(SendEmail.java:38)
05-26 19:59:55.807: W/System.err(3103): at utils.SendEmail.doInBackground(SendEmail.java:1)
05-26 19:59:55.819: W/System.err(3103): at android.os.AsyncTask$2.call(AsyncTask.java:264)
05-26 19:59:55.827: W/System.err(3103): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
05-26 19:59:55.827: W/System.err(3103): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
05-26 19:59:55.837: W/System.err(3103): at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
05-26 19:59:55.837: W/System.err(3103): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
05-26 19:59:55.847: W/System.err(3103): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
05-26 19:59:55.847: W/System.err(3103): at java.lang.Thread.run(Thread.java:856)
05-26 19:59:55.956: W/System.err(3103): Caused by: libcore.io.GaiException: getaddrinfo failed: EAI_NODATA (No address associated with hostname)
05-26 19:59:56.177: D/dalvikvm(3103): GC_CONCURRENT freed 406K, 6% free 9330K/9863K, paused 32ms+6ms
但异常并不准确。我能够解决该主机没问题。在我添加BaseListActivity之前，这个代码曾经用过。
谢谢！
答案 0 :(得分：1)
将ListAdapter重新设置为ListView将与调用adapter.notifyDataSetChanged();相同，我认为notifyDataSetChanged();仅在您使用数据库Cursor对象时才有效数据提供者。而不是adapter.notifyDataSetChanged();只需致电setListAdapter();哪个实习生将重建ListView。