android - Android 停止開始 AsyncTask

Question

AutoCompleteTextView からテキストを取得して解析し、Google マップで住所を入力するときと同じように住所のドロップダウンリストを表示する AsyncTask (AddressUpdaterTask) があります。ユーザーが文字を入力するたびに、新しい AddressUpdaterTask が実行されます。私の問題は、ユーザーが入力を開始したときに十分に速く入力すると、前のタスクの実行が完了していない間に新しい AsyncTask が実行されるため、これは効率的ではないことです。

だから私はこれをしました：

AddressUpdaterTask addressUpdaterTask = new AddressUpdaterTask();

addressUpdaterTask はグローバルであり、ユーザーが文字を入力すると、次のようになります。

addressUpdaterTask.cancel(true);
addressUpdaterTask.execute();

したがって、AddressUpdaterTask の 1 つのインスタンスを操作できます。しかし、この方法ではうまくいきません:(どうすれば欲しいものを実装できますか?

編集:これが私のコードです:

public class RegisterDoctor extends Activity {

        .
        .
        .

    private AutoCompleteTextView addressField;
    private ArrayAdapter<String> adapter;
    private Filter filter;
    private List<SimpleAddress> simpleAddresses = new ArrayList<SimpleAddress>();
    private SimpleAddress currentAddress = null;
    AddressUpdaterTask addressUpdaterTask = new AddressUpdaterTask();



    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.register_doctor);

        .
        .
        .


        //AutoCompleteTextView Creation
        addressField = (AutoCompleteTextView) findViewById(R.id.addressEditText);
        addressField.setThreshold(ADDRESS_TRESHOLD);
        addressField.setHint("Οδός Αριθμός, Περιοχή");
        filter = new Filter() {
            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {
                adapter.notifyDataSetChanged();
            }

            @Override
            protected FilterResults performFiltering(CharSequence constraint) {
                Log.i("FILTER_ACTION", "Filter:" + constraint);
                if (constraint != null && constraint.length() > ADDRESS_TRESHOLD) {
                    Log.i("FILTER_ACTION", "doing a search ..");
                    addressUpdaterTask.cancel(true);
                    addressUpdaterTask.execute();
                }
                return null;
            }
        };
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line) {
            public android.widget.Filter getFilter() {
                return filter;
            }
        };
        addressField.setAdapter(adapter);
        adapter.setNotifyOnChange(false);
        addressField.setOnItemClickListener(itemClicked);

        .
        .
        .

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }


    private AdapterView.OnItemClickListener itemClicked = new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View arg1, int pos, long id) {
            currentAddress = simpleAddresses.get(pos);
            Log.i("ITEM_CLICKED", simpleAddresses.get(pos).getFormatted_address());
        }
    };

        .
        .
        .

    public class AddressUpdaterTask extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            //adapter.clear();
        }


        @Override
        protected Void doInBackground(Void... voids) {
            try {
                simpleAddresses = new JsonHelper().getAddresses(addressField.getText().toString());
            } catch (NullPointerException e) {
            }
            return null;
        }
@Override
        protected void onPostExecute(Void aVoid) {
            int size = simpleAddresses.size();

            if (size > 0) {
                adapter.clear();
                for (int i = 0; i < size; i++) {
                    adapter.add(simpleAddresses.get(i).getFormatted_address());
                    Log.i("ADDRESS_ADDED", simpleAddresses.get(i).getFormatted_address());
                }
                adapter.notifyDataSetChanged();
                addressField.showDropDown();
            }
            super.onPostExecute(aVoid);
        }
    }
        .
        .
        .
}

編集2：ユーザーが入力した瞬間からのlogcatは次のとおりです=> 6文字（私が設定したしきい値）で、AsyncTaskを実行できます：

10-11 18:56:59.795    1465-1494/com.user.project I/FILTER_ACTION: Filter:panepi
10-11 18:57:02.695    1465-1494/com.user.project I/FILTER_ACTION: Filter:panepis
10-11 18:57:02.695    1465-1494/com.user.project I/FILTER_ACTION: doing a search ..
10-11 18:57:06.544    1465-1496/com.user.project I/FILTER_ACTION: Filter:panepist
10-11 18:57:06.544    1465-1496/com.user.project I/FILTER_ACTION: doing a search ..
10-11 18:57:06.555    1465-1496/com.user.project W/Filter: An exception occured during performFiltering()!
        java.lang.IllegalStateException: Cannot execute task: the task has already been executed (a task can be executed only once)
        at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:578)
        at android.os.AsyncTask.execute(AsyncTask.java:534)
        at com.user.project.RegisterDoctor$2.performFiltering(RegisterDoctor.java:104)
        at android.widget.Filter$RequestHandler.handleMessage(Filter.java:234)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.os.HandlerThread.run(HandlerThread.java:60)
10-11 18:57:09.004    1465-1496/com.user.project I/FILTER_ACTION: Filter:panepisti
10-11 18:57:09.004    1465-1496/com.user.project I/FILTER_ACTION: doing a search ..
10-11 18:57:09.014    1465-1496/com.user.project W/Filter: An exception occured during performFiltering()!
        java.lang.IllegalStateException: Cannot execute task: the task has already been executed (a task can be executed only once)
        at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:578)
        at android.os.AsyncTask.execute(AsyncTask.java:534)
        at com.user.project.RegisterDoctor$2.performFiltering(RegisterDoctor.java:104)
        at android.widget.Filter$RequestHandler.handleMessage(Filter.java:234)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.os.HandlerThread.run(HandlerThread.java:60)
10-11 18:57:09.904    1465-1496/com.user.project I/FILTER_ACTION: Filter:panepistim
10-11 18:57:09.904    1465-1496/com.user.project I/FILTER_ACTION: doing a search ..
10-11 18:57:09.914    1465-1496/com.user.project W/Filter: An exception occured during performFiltering()!
        java.lang.IllegalStateException: Cannot execute task: the task has already been executed (a task can be executed only once)
        at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:578)
        at android.os.AsyncTask.execute(AsyncTask.java:534)
        at com.user.project.RegisterDoctor$2.performFiltering(RegisterDoctor.java:104)
        at android.widget.Filter$RequestHandler.handleMessage(Filter.java:234)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.os.HandlerThread.run(HandlerThread.java:60)
10-11 18:57:10.194    1465-1496/com.user.project I/FILTER_ACTION: Filter:panepistimi
10-11 18:57:10.194    1465-1496/com.user.project I/FILTER_ACTION: doing a search ..
10-11 18:57:10.194    1465-1496/com.user.project W/Filter: An exception occured during performFiltering()!
        java.lang.IllegalStateException: Cannot execute task: the task has already been executed (a task can be executed only once)
        at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:578)
        at android.os.AsyncTask.execute(AsyncTask.java:534)
        at com.user.project.RegisterDoctor$2.performFiltering(RegisterDoctor.java:104)
        at android.widget.Filter$RequestHandler.handleMessage(Filter.java:234)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.os.HandlerThread.run(HandlerThread.java:60)
10-11 18:57:11.865    1465-1496/com.user.project I/FILTER_ACTION: Filter:panepistimio
10-11 18:57:11.865    1465-1496/com.user.project I/FILTER_ACTION: doing a search ..
10-11 18:57:11.954    1465-1496/com.user.project W/Filter: An exception occured during performFiltering()!
        java.lang.IllegalStateException: Cannot execute task: the task has already been executed (a task can be executed only once)
        at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:578)
        at android.os.AsyncTask.execute(AsyncTask.java:534)
        at com.user.project.RegisterDoctor$2.performFiltering(RegisterDoctor.java:104)
        at android.widget.Filter$RequestHandler.handleMessage(Filter.java:234)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.os.HandlerThread.run(HandlerThread.java:60)
10-11 18:57:12.196    1465-1496/com.user.project I/FILTER_ACTION: Filter:panepistimiou
10-11 18:57:12.196    1465-1496/com.user.project I/FILTER_ACTION: doing a search ..
10-11 18:57:12.295    1465-1496/com.user.project W/Filter: An exception occured during performFiltering()!
        java.lang.IllegalStateException: Cannot execute task: the task has already been executed (a task can be executed only once)
        at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:578)
        at android.os.AsyncTask.execute(AsyncTask.java:534)
        at com.user.project.RegisterDoctor$2.performFiltering(RegisterDoctor.java:104)
        at android.widget.Filter$RequestHandler.handleMessage(Filter.java:234)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.os.HandlerThread.run(HandlerThread.java:60)
10-11 18:57:14.795      404-966/com.android.inputmethod.latin E/ActivityThread: Failed to find provider info for com.android.inputmethod.latin.dictionarypack
10-11 18:57:14.805      404-966/com.android.inputmethod.latin E/BinaryDictionaryGetter: Could not find a dictionary pack
10-11 18:57:14.815    1465-1496/com.user.project I/FILTER_ACTION: Filter:panepistimiou
10-11 18:57:14.815    1465-1496/com.user.project I/FILTER_ACTION: doing a search ..
10-11 18:57:14.815    1465-1496/com.user.project W/Filter: An exception occured during performFiltering()!
        java.lang.IllegalStateException: Cannot execute task: the task has already been executed (a task can be executed only once)
        at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:578)
        at android.os.AsyncTask.execute(AsyncTask.java:534)
        at com.user.project.RegisterDoctor$2.performFiltering(RegisterDoctor.java:104)
        at android.widget.Filter$RequestHandler.handleMessage(Filter.java:234)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.os.HandlerThread.run(HandlerThread.java:60)

score 0 · Accepted Answer

オートコンプリートを実装するときは、通常、結果を返さずにサービスが複数回呼び出されないように、ある程度の遅延を導入します。

ユーザーが最初の入力をいつ入力したかを追跡する変数 (おそらく静的) を追加し、特定の期間 (500 ～ 750 ミリ秒がかなり一般的) が経過した後にのみ検索を実行してみてください。これは優れた UX ですが、最初の問題は解決しません。

「二重実行」の問題については、リクエストの開始時に true に設定され、終了時に false に設定される条件を設定するだけで、変数が設定されている間は別のリクエストを開始できません。

このようなもの：

bool requestInProgress = false;

...

@Override
protected void onPreExecute() {
    super.onPreExecute();
    requestInProgress = true;
}

protected void onPostExecute(Void aVoid) {
    int size = simpleAddresses.size();

    if (size > 0) {
        adapter.clear();
        for (int i = 0; i < size; i++) {
            adapter.add(simpleAddresses.get(i).getFormatted_address());
            Log.i("ADDRESS_ADDED", simpleAddresses.get(i).getFormatted_address());
        }
        adapter.notifyDataSetChanged();
        addressField.showDropDown();
    }
    super.onPostExecute(aVoid);
    requestInProgress = false;
}

そして上...

@Override
protected FilterResults performFiltering(CharSequence constraint) {
    Log.i("FILTER_ACTION", "Filter:" + constraint);
    if (constraint != null && constraint.length() > ADDRESS_TRESHOLD 
           && !requestInProgress) {
        Log.i("FILTER_ACTION", "doing a search ..");
        addressUpdaterTask.cancel(true);
        addressUpdaterTask.execute();
    }
    return null;
}

android - Android 停止開始 AsyncTask

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