我有一个应用程序，可以将json提要中的信息加载到列表视图中。这需要一点时间加载，所以我想设置一个进度条让用户知道应用程序正在做什么。我是否必须实现AsyncTask，或者是否有一种简单的方法可以在加载列表时显示旋转进度图标？我假设我需要将progressdialog代码放在我正在加载的任务中。这是我的listview的代码。
public class Schedule extends ListActivity {
protected EditText searchText;
protected SQLiteDatabase db;
protected Cursor cursor;
protected TextView textView;
protected ImageView imageView;
protected ArrayList<HashMap<String, String>> myList;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.schedule);
View layout = findViewById(R.id.gradiant);
GradientDrawable gd = new GradientDrawable(
GradientDrawable.Orientation.TOP_BOTTOM, new int[] {
0xFF95B9C7, 0xFF06357A });
gd.setCornerRadius(2f);
layout.setBackgroundDrawable(gd);
myList = new ArrayList<HashMap<String, String>>();
JSONObject jsonObjSend = new JSONObject();
JSONObject json = JSONfunctions
.getJSONfromURL("myAPIURL");
try {
JSONArray current = json.getJSONArray("d");
for (int i = 0; i < current.length(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = current.getJSONObject(i);
map.put("id", String.valueOf(i));
map.put("showid", "" + Html.fromHtml(e.getString("ShowID")));
map.put("name", "" + Html.fromHtml(e.getString("Title")));
map.put("showvenue", "" + e.getString("ShowVenue"));
map.put("subtitle", "" + Html.fromHtml(e.getString("SubTitle")));
map.put("venueid", "" + e.getString("VenueID"));
String showDate = e.getString("ShowDate");
long epoch = Long.parseLong(showDate);
Date showDatePresent = new Date(epoch * 1000);
SimpleDateFormat sdf = new SimpleDateFormat("E, MMMM d");
String dateOfShow = sdf.format(showDatePresent);
map.put("showdate", "" + dateOfShow);
String showStart = e.getString("ShowStart");
long epoch2 = Long.parseLong(showStart);
Date showTimePresent = new Date(epoch2 * 1000);
SimpleDateFormat sdf2 = new SimpleDateFormat("h:mm a");
String timeOfShow = sdf2.format(showTimePresent);
map.put("showstart", "" + timeOfShow);
String showEnd = e.getString("ShowEnd");
long epoch3 = Long.parseLong(showEnd);
Date showEndPresent = new Date(epoch3 * 1000);
SimpleDateFormat sdf3 = new SimpleDateFormat("h:mm a");
String endOfShow = sdf3.format(showEndPresent);
map.put("showend", "" + endOfShow);
String gatesOpen = e.getString("GatesOpen");
long epoch4 = Long.parseLong(gatesOpen);
Date gatesOpenPresent = new Date(epoch4 * 1000);
SimpleDateFormat sdf4 = new SimpleDateFormat(
"'Gates open: 'h:mm a");
String gatesAreOpen = sdf4.format(gatesOpenPresent);
map.put("gatesopen", "" + gatesAreOpen);
map.put("aboutartist", "" + e.getString("AboutArtist"));
map.put("program", "" + Html.fromHtml(e.getString("Program")));
map.put("programnotes",
"" + Html.fromHtml(e.getString("ProgramNotes")));
map.put("pricing", "" + Html.fromHtml(e.getString("Pricing")));
map.put("featuring", "" + e.getString("Featuring"));
map.put("parkdetails", "" + e.getString("ParkDetails"));
map.put("starred", "" + e.getString("Starred"));
map.put("image500", "" + e.getString("Image500"));
map.put("image250", "" + e.getString("Image250"));
map.put("aboutartist",
"" + Html.fromHtml(e.getString("AboutArtist")));
myList.add(map);
}
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
ListAdapter adapter = new SimpleAdapter(this, myList,
R.layout.line_item, new String[] { "name", "showdate",
"showstart", "showvenue" }, new int[] { R.id.title,
R.id.showdate, R.id.showstart, R.id.showvenue });
setListAdapter(adapter);
final ListView lv = getListView();
lv.setTextFilterEnabled(true);
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
HashMap<String, String> hashMap = myList.get(position);
// hashMap.put("map", hashMap);
Intent intent = new Intent(getApplicationContext(),
ArtistDetails.class);
intent.putExtra("map", hashMap);
startActivity(intent);
}
});
}
public void featured(View view) {
startActivity(new Intent(getApplicationContext(), Featured.class));
}
public void schedule(View view) {
startActivity(new Intent(getApplicationContext(), Schedule.class));
}
public void venue(View view) {
startActivity(new Intent(getApplicationContext(), Venues.class));
}
public void share(View view) {
startActivity(new Intent(getApplicationContext(), Friends.class));
}
public void myravinia(View view) {
startActivity(new Intent(getApplicationContext(), Account.class));
}
希望我的问题很明确，如果您需要我显示任何其他详细信息，请与我联系。
答案 0 :(得分：0)
执行您要完成的任务的最佳方法是确保该任务是异步任务。因此，当您获得JSON提要时，它需要是一个异步任务，因为您希望同时运行另一个任务，这将是您的进度对话框。如果你没有使它异步，那么进度对话框似乎被冻结，可能会崩溃正在运行的同步任务，这是你的JSON提要。我会考虑让你的JSON feed任务异步。
答案 1 :(得分：0)
你可以这样做：
final Handler handler = new Handler();
dialog = ProgressDialog.show(Events.this, "Wait", "Please wait...", false);
new Thread()
{
public void run()
{
// Do a lot of funny things with json here in background
handler.post(new Runnable()
{
public void run()
{
if(dialog != null)
dialog.dismiss();
}
}
}
}
答案 2 :(得分：0)
您可以使用asynctask
尝试此方法protected class ParsingTask extends AsyncTask<Context, String, ArrayList<Items>> {
private ProgressDialog loadingDialog = new ProgressDialog(JsonParserActivity.this);
protected void onPreExecute() {
loadingDialog.setMessage("loading app store..");
loadingDialog.show();
}
//items is a list of model class item
@Override
protected ArrayList<Items> doInBackground( Context... params ) {
String source = getJsonString(url);
try {
// do ur parsing here with the above source.
}
catch (Throwable e) {
e.printStackTrace();
}
return result;
}
catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if (source != null) {
}
if (!this.isCancelled()) {
}
return result;
}
@Override
protected void onProgressUpdate(String... s) {
super.onProgressUpdate(s);
Toast.makeText(getApplicationContext(), s[0], Toast.LENGTH_SHORT).show();
}
@Override
protected void onPostExecute( ArrayList<Items> response ) {
// st ur list view here
mListView.setAdapter(new JsonListAdapter(JsonParserActivity.this));
loadingDialog.dismiss();
}
@Override
protected void onCancelled() {
super.onCancelled();
Toast.makeText(getApplicationContext(), "The operation was cancelled", 1).show();
}
private String getJsonString(String url) {
DefaultHttpClient client = new DefaultHttpClient();
HttpGet getRequest;
try {
getRequest = new HttpGet(url);
HttpResponse getResponse = client.execute(getRequest);
HttpEntity getResponseEntity = getResponse.getEntity();
return EntityUtils.toString(getResponseEntity);
} catch (Exception e) {
Log.w(getClass().getSimpleName(), "Error for URL " + url, e);
return null;
}
}
}
答案 3 :(得分：0)
谢谢大家的帮助。从中我就能够提出一个解决方案。这里有比以前更多的代码，但这里有用。
public class Schedule extends ListActivity {
protected EditText searchText;
protected SQLiteDatabase db;
protected Cursor cursor;
protected TextView textView;
protected ImageView imageView;
protected ArrayList<HashMap<String, String>> myList;
protected ImageLoader imageLoader;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.schedule);
View layout = findViewById(R.id.gradiant);
GradientDrawable gd = new GradientDrawable(
GradientDrawable.Orientation.TOP_BOTTOM, new int[] {
0xFF95B9C7, 0xFF06357A });
gd.setCornerRadius(2f);
layout.setBackgroundDrawable(gd);
new GetEventsTask().execute("blah");
}
public void featured(View view) {
startActivity(new Intent(getApplicationContext(), Featured.class));
}
public void schedule(View view) {
}
public void venue(View view) {
startActivity(new Intent(getApplicationContext(), Venues.class));
}
public void share(View view) {
startActivity(new Intent(getApplicationContext(), Friends.class));
}
public void myravinia(View view) {
startActivity(new Intent(getApplicationContext(), Account.class));
}
protected class GetEventsTask extends
AsyncTask<String, Integer, ArrayList<HashMap<String, String>>> {
protected ArrayList<HashMap<String, String>> threadList;
private final ProgressDialog dialog = new ProgressDialog(Schedule.this);
protected void onPreExecute() {
this.dialog.setMessage("Loading...");
this.dialog.setCancelable(false);
this.dialog.show();
}
@Override
protected ArrayList<HashMap<String, String>> doInBackground(
String... params) {
Log.v("Yup", "The thread is running");
threadList = new ArrayList<HashMap<String, String>>();
JSONObject json = JSONfunctions
.getJSONfromURL("my.json.feed.url");
try {
JSONArray current = json.getJSONArray("d");
for (int i = 0; i < current.length(); i++) {
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = current.getJSONObject(i);
map.put("id", String.valueOf(i));
map.put("showid", "" + Html.fromHtml(e.getString("ShowID")));
map.put("name", "" + Html.fromHtml(e.getString("Title")));
map.put("showvenue", "" + e.getString("ShowVenue"));
map.put("subtitle",
"" + Html.fromHtml(e.getString("SubTitle")));
map.put("venueid", "" + e.getString("VenueID"));
String showDate = e.getString("ShowDate");
long epoch = Long.parseLong(showDate);
Date showDatePresent = new Date(epoch * 1000);
SimpleDateFormat sdf = new SimpleDateFormat("E, MMMM d");
String dateOfShow = sdf.format(showDatePresent);
map.put("showdate", "" + dateOfShow);
String showStart = e.getString("ShowStart");
long epoch2 = Long.parseLong(showStart);
Date showTimePresent = new Date(epoch2 * 1000);
SimpleDateFormat sdf2 = new SimpleDateFormat("h:mm a");
String timeOfShow = sdf2.format(showTimePresent);
map.put("showstart", "" + timeOfShow);
String showEnd = e.getString("ShowEnd");
long epoch3 = Long.parseLong(showEnd);
Date showEndPresent = new Date(epoch3 * 1000);
SimpleDateFormat sdf3 = new SimpleDateFormat("h:mm a");
String endOfShow = sdf3.format(showEndPresent);
map.put("showend", "" + endOfShow);
String gatesOpen = e.getString("GatesOpen");
long epoch4 = Long.parseLong(gatesOpen);
Date gatesOpenPresent = new Date(epoch4 * 1000);
SimpleDateFormat sdf4 = new SimpleDateFormat(
"'Gates open: 'h:mm a");
String gatesAreOpen = sdf4.format(gatesOpenPresent);
map.put("gatesopen", "" + gatesAreOpen);
map.put("aboutartist", "" + e.getString("AboutArtist"));
map.put("program",
"" + Html.fromHtml(e.getString("Program")));
map.put("programnotes",
"" + Html.fromHtml(e.getString("ProgramNotes")));
map.put("pricing",
"" + Html.fromHtml(e.getString("Pricing")));
map.put("featuring", "" + e.getString("Featuring"));
map.put("parkdetails", "" + e.getString("ParkDetails"));
map.put("starred", "" + e.getString("Starred"));
map.put("image500", "" + e.getString("Image500"));
map.put("image250", "" + e.getString("Image250"));
map.put("aboutartist",
"" + Html.fromHtml(e.getString("AboutArtist")));
threadList.add(map);
}
} catch (JSONException e) {
Log.e("log_tag", "Error parsing data " + e.toString());
}
return threadList;
}
protected void onPostExecute(ArrayList<HashMap<String, String>> result) {
myList = new ArrayList<HashMap<String, String>>();
myList = result;
LazyAdapter adapter = new LazyAdapter(Schedule.this, myList);
setListAdapter(adapter);
final ListView lv = getListView();
lv.setTextFilterEnabled(true);
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
HashMap<String, String> hashMap = myList.get(position);
// hashMap.put("map", hashMap);
Intent intent = new Intent(getApplicationContext(),
ArtistDetails.class);
intent.putExtra("map", hashMap);
startActivity(intent);
}
});
if (this.dialog.isShowing()) {
this.dialog.dismiss();
}
}
}
}