我使用文件 CSV 的动态表创建简单的 Activity。我想在读取文件和构建 UI 之前简单地显示进度条。我坚持 AsyncTask ..
如果我执行 mytask.get() 则 UI 构建被阻止并且我想要的 progressDialog 将不会显示。但是，如果我调用 mytask.get() 则应用程序崩溃，因为我所有的 UI 都依赖于该 CSV。我找到了这个：
调用 AsyncTask.get() 时未显示 ProgressDialog
与相关：
但我什至无法想象如何在我的案例中使用这个概念..
public void onCreate(Bundle savedInstanceState) {
...
Log.i(TAG, "before csv:");
ReadFromCSV mytask = new ReadFromCSV(this);
mytask.execute(char_name);
// try {
// mytask.get();
// } catch (InterruptedException e1) {
// // TODO Auto-generated catch block
// Log.i(TAG, "1 exception");
// e1.printStackTrace();
// } catch (ExecutionException e1) {
// Log.i(TAG, "2 exception");
// e1.printStackTrace();
// }
Log.i(TAG, "after csv");
// create table from var headers
set_title_with_charname(flipper.get_moves_group(0)); //set activity title
Log.i(TAG, "headers values:" + headers);
heading.create_header(this, headers, 0);
lay.addView(heading);
lay.addView(flipper);
lay.setOrientation(1);
setContentView(lay);
}
这是我的任务：
private class ReadFromCSV extends AsyncTask<String, Void, String> {
public Activity activity;
private ProgressDialog Dialog = new ProgressDialog(MovesList.this);
public ReadFromCSV(Activity a) {
activity = a;
}
protected void onPreExecute() {
Log.i(TAG, "start onPreExecute");
Dialog.setMessage("Please wait...");
Dialog.show();
Log.i(TAG, "END onPreExecute");
}
protected String doInBackground(String... urls) {
Log.i(TAG, "doInBackground");
// return loadImageFromNetwork(urls[0]);
String new_val = urls[0] + "doInBack";
Log.i(TAG, "new_val: " + new_val);
try {
readfromcsv(flipper, char_name);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Log.i(TAG, "END doInBackground");
return new_val;
}
protected void onPostExecute(String result) {
Log.i(TAG, "onpostexecute");
Log.i(TAG, "result: " + result);
try {
if(Dialog.isShowing()) {
Dialog.dismiss();
}
// do your Display and data setting operation here
}
catch(Exception e) {
Log.i(TAG, "exception: ");
}
Log.i(TAG, "END onPostExecute");
}
}
这是 readfromcsv 的代码：
public void readfromcsv(MyFlipper flipper, String char_name)
throws IOException {
String filename = char_name + ".csv";
InputStream is = getAssets().open(filename);
BufferedReader in = new BufferedReader(new InputStreamReader(is,
"UTF-8"));
String reader = "";
int line_nb = 0;
MyTable table = null;
while ((reader = in.readLine()) != null) {
line_nb += 1;
Log.d(TAG, "file line: " + reader);
String[] row_data = reader.split("ą");
Log.d(TAG, "splitted: " + row_data[0] + ',' + row_data[1] + "..");
if (line_nb == 1) {
Log.i(TAG, "first row - memorized headers..");
headers = row_data;
Log.i(TAG, "headers memorized: " + row_data[0] + ","
+ row_data[1] + "..");
continue;
}
if (row_data[0].equals("")) {
// new table
// Log.i(TAG, "new moves_group..");
if (table != null) {
add_table(table);
}
Log.d(TAG, "creating new table");
table = new MyTable(this, true, row_data[1]);
Log.d(TAG, "new table created");
continue;
}
Log.d(TAG, "regular row..");
table.row_from_template(this, row_data, line_nb % 2);
if (line_nb == 60) {
break;
}
;
}
add_table(table);
in.close();
}