我有一个非异步方法应该调用显示UIAlertView的异步方法。如果单击了Button，则此异步方法返回int。
public Task<int> ShowAlertAsync(string title, string message, params string[] buttons)
{
var tcs = new TaskCompletionSource<int>();
var alert = new UIAlertView
{
Title = title,
Message = message
};
if (buttons.Length > 0)
{
foreach (var button in buttons)
{
alert.AddButton(button);
}
}
else
{
alert.AddButton("OK");
}
alert.Clicked += (s, e) => { tcs.TrySetResult((int)e.ButtonIndex); };
alert.Show();
return tcs.Task;
}
如果我从异步方法调用它，这可以正常工作，但问题是我有一个肯定无法转换为异步的同步方法，所以我需要以同步方式调用此方法并等待为了回应。在sync方法获得结果后，它应该继续执行。
我尝试了许多解决方案，这些解决方案都没有编译或阻止MainThread，并且UIAlertView将不会显示。
也许有人知道我该怎么做，或者可能有更好的解决方案。
提前致谢！
答案 0 :(得分：1)
可能的解决办法可能是使用ContinueWith。
例如：
public class History extends Fragment {
final int PAGE_COUNT = 3;
private String tabTitles[] = new String[]{"Tab1", "Tab2", "Tab3"};
public static final String ARG_PAGE = "ARG_PAGE";
private static final int NUM_PAGES = 3;
String medicinename,medicinepercentage,numberdosages,time;
String date,day,daypercentage;
String month,monthdata;
/**
* The pager widget, which handles animation and allows swiping horizontally to access previous
* and next wizard steps.
*/
private ViewPager mPager;
/**
* The pager adapter, which provides the pages to the view pager widget.
*/
private PagerAdapter mPagerAdapter;
private int selectedPage; // set selected page
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
DonutProgress dp;
DonutProgress dp2;
DonutProgress dp3;
public static History newInstance(int page) {
Bundle args = new Bundle();
args.putInt(ARG_PAGE, page);
History fragment = new History();
fragment.setArguments(args);
return fragment;
}
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private Paint progressPaint = new Paint();
private int lineHeight = 30;
private Paint incompletePaint = new Paint();
public History() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment History.
*/
// TODO: Rename and change types and number of parameters
public static History newInstance(String param1, String param2) {
History fragment = new History();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v = inflater.inflate(R.layout.fragment_history, container, false);
dp = (DonutProgress) v.findViewById(R.id.donut_progress1);
dp2 = (DonutProgress) v.findViewById(R.id.donut_progress2);
dp3 = (DonutProgress) v.findViewById(R.id.donut_progress3);
if (getArguments() != null)
{
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
mPager = (ViewPager) v.findViewById(R.id.pager); //the UI pager
mPagerAdapter = new ScreenSlidePagerAdapter(getFragmentManager());
mPager.setAdapter(mPagerAdapter);
// mPager.setPageTransformer(true, new RotateDownTransformer()); //set the animation
selectedPage = 0; //current page
if (savedInstanceState != null) { //if app was paused, you can reopen the same page
selectedPage = savedInstanceState.getInt("SELECTED_PAGE");
}
selectedPage = 1; //current page
if (savedInstanceState != null) { //if app was paused, you can reopen the same page
selectedPage = savedInstanceState.getInt("SELECTED_PAGE");
}
selectedPage = 2; //current page
if (savedInstanceState != null) { //if app was paused, you can reopen the same page
selectedPage = savedInstanceState.getInt("SELECTED_PAGE");
}
selectedPage = 3; //current page
if (savedInstanceState != null) { //if app was paused, you can reopen the same page
selectedPage = savedInstanceState.getInt("SELECTED_PAGE");
}
mPager.setCurrentItem(selectedPage);//set the current page
mPager.setOffscreenPageLimit(4);
return v;
// return inflater.inflate(R.layout.fragment_history, container, false);
}
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter{
public ScreenSlidePagerAdapter(FragmentManager fm) {
super(fm);
}
int i = 0;
@Override
public Fragment getItem(int position)
{
if(position==0){
Log.e("Fragment","Fragment 1::"+String.valueOf(i));
new Progress(100).execute();
new Progress2(20).execute();
new Progress3(30).execute();
return SlideFragment.newInstance(0, " ");}
if(position==1){
Log.e("Fragment","Fragment 2");
new Progress(40).execute();
new Progress2(50).execute();
new Progress3(90).execute();
return Slidetwo.newInstance(String.valueOf(0), " ");}
if (position==2)
Log.e("Fragment","Fragment 3");
new Progress(50).execute();
new Progress2(10).execute();
new Progress3(40).execute();
return SlideThree.newInstance(String.valueOf(0), " ");
}
@Override
public int getCount()
{
return NUM_PAGES;
}
}
class Progress extends AsyncTask<Void, Integer, Integer>
{
int dummyVariable = 0;
Progress(int dummyVariable)
{
this.dummyVariable = dummyVariable;
}
@Override
protected void onPreExecute() {
super.onPreExecute();
dp.setMax(100);
}
@Override
protected Integer doInBackground(Void... params)
{
for (int i = 0; i <= dummyVariable; i++)
{
publishProgress(i);
try
{
Thread.sleep(20);
}
catch (InterruptedException ie)
{
ie.printStackTrace();
}
}
return null;
}
@Override
protected void onProgressUpdate(Integer... values)
{
super.onProgressUpdate(values);
dp.setProgress(values[0]);
}
@Override
protected void onPostExecute(Integer integer)
{
super.onPostExecute(integer);
}
}
class Progress2 extends AsyncTask<Void, Integer, Integer>
{
int dummyVariable = 0;
Progress2(int dummyVariable)
{
this.dummyVariable = dummyVariable;
}
@Override
protected void onPreExecute()
{
super.onPreExecute();
dp2.setMax(100);
}
@Override
protected Integer doInBackground(Void... params)
{
for (int i = 0; i <= dummyVariable; i++)
{
publishProgress(i);
try {
Thread.sleep(20);
}
catch (InterruptedException ie)
{
ie.printStackTrace();
}
}
return null;
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
dp2.setProgress(values[0]);
}
@Override
protected void onPostExecute(Integer integer) {
super.onPostExecute(integer);
}
}
class Progress3 extends AsyncTask<Void, Integer, Integer>
{
int dummyVariable = 0;
Progress3(int dummyVariable)
{
this.dummyVariable = dummyVariable;
}
@Override
protected void onPreExecute()
{
super.onPreExecute();
dp3.setMax(100);
}
@Override
protected Integer doInBackground(Void... params)
{
for (int i = 0; i <= dummyVariable; i++) {
publishProgress(i);
try
{
Thread.sleep(20);
}
catch (InterruptedException ie)
{
ie.printStackTrace();
}
}
return null;
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate(values);
dp3.setProgress(values[0]);
}
@Override
protected void onPostExecute(Integer integer) {
super.onPostExecute(integer);
}
}
如果需要使用当前上下文，则可以扩展ContinueWith方法
ShowAlertAsyc("title","message",...).ContinueWith(t=>
{
//t.Result contains the return value
});