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安卓 - 当回退时AutoCompleteTextView才能工作

androidautocompletetextview
4

我有一个AutoCompleteTextView，它会随着用户的输入动态更新建议列表。我的问题是当我输入时，列表被更新了，但下拉框没有显示出来！但是当我删除一个字符（退格）时，下拉框就会显示出来！

我甚至尝试在文本更改后显式调用autoText.showDropDown();，但它不起作用。

这是我的TextChangedListener：

private TextWatcher textChecker = new TextWatcher() {
    @Override
    public void beforeTextChanged(CharSequence charSequence, int i, int i2, int i3) {

    }

    @Override
    public void onTextChanged(CharSequence charSequence, int i, int i2, int i3) {
        if(autoText.length()>9){
            new GeoTask().execute();
        }
    }

    @Override
    public void afterTextChanged(Editable editable) {
        if(autoText.length()>9){
            autoText.showDropDown();
            Log.i("UPDATE","showDropDown");
        }
    }
};

我甚至尝试了在autoText.showDropDown();之前重置适配器，但仍然没有任何反应：
autoText.setAdapter(null);
autoText.setAdapter(adapter);

有没有一种方法使其正常工作？

编辑: 这是活动的完整代码。也许有人可以找出我错在哪里...

public class TestDoctor extends Activity {

    TextView latText;
    TextView lngText;
    AutoCompleteTextView autoText;
    ArrayAdapter<String> adapter;

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

        latText = (TextView) findViewById(R.id.latTextView);
        lngText = (TextView) findViewById(R.id.longTextView);
        autoText = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView);


        Button button = (Button) findViewById(R.id.buttonDoctor);
        button.setOnClickListener(new Button.OnClickListener() {
            public void onClick(View v) {
                new GeoTask().execute();
            }
        });
        autoText.setThreshold(10);
        autoText.setHint("Οδός Αριθμός, Περιοχή");
        adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line);
        autoText.setAdapter(adapter);
        adapter.setNotifyOnChange(true);
        autoText.addTextChangedListener(textChecker);
    }

    private TextWatcher textChecker = new TextWatcher() {

        @Override
        public void beforeTextChanged(CharSequence charSequence, int i, int i2, int i3){}

        @Override
        public void onTextChanged(CharSequence charSequence, int i, int i2, int i3) {
            if(autoText.length()>9){
                new GeoTask().execute();
            }
        }

        @Override
        public void afterTextChanged(Editable editable) {}
    };

    @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 List<SimpleAddress> getAddressesFromText(String address) {
        address = address.replace(' ', '+');
        HttpHelper httpHelper = new HttpHelper();
        InputStream inputStream = httpHelper.makeHttpGetRequest("http://maps.google.com/maps/api/geocode/json?address=" + address + "&sensor=false");
        String response = httpHelper.inputStreamToString(inputStream);

        List<SimpleAddress> simpleAddresses = new ArrayList<SimpleAddress>();
        try {
            JSONObject jsonObject = new JSONObject(response);


            int size = ((JSONArray) jsonObject.get("results")).length();

            for (int i = 0; i<size; i++){
                String formatted_address = ((JSONArray) jsonObject.get("results")).getJSONObject(i)
                        .getString("formatted_address");

                Double lng = ((JSONArray) jsonObject.get("results")).getJSONObject(i)
                        .getJSONObject("geometry").getJSONObject("location")
                        .getDouble("lng");

                Double lat = ((JSONArray) jsonObject.get("results")).getJSONObject(i)
                        .getJSONObject("geometry").getJSONObject("location")
                        .getDouble("lat");
                simpleAddresses.add(i,new SimpleAddress(formatted_address,lat,lng));
            }
            return simpleAddresses;
        } catch (JSONException e) {
            return null;
        }
    }

    public class GeoTask extends AsyncTask<Void, Void, Void> {
        List<SimpleAddress> simpleAddresses = new ArrayList<SimpleAddress>();

        @Override
        protected Void doInBackground(Void... voids) {
            Log.i("UPDATE","1");
            try {
                simpleAddresses = getAddressesFromText(autoText.getText().toString());
            } catch (NullPointerException e) {
            }
            Log.i("UPDATE","2");
            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid) {
            Log.i("UPDATE", "3");

            int size = simpleAddresses.size();

            if(size > 0){
                adapter.clear();
                Log.i("ADAPTER_SIZE",""+size);
                for (int i = 0; i< size; i++){
                    adapter.add(simpleAddresses.get(i).getFormatted_address());
                    Log.i("ADDED",simpleAddresses.get(i).getFormatted_address());
                }
                Log.i("UPDATE","4");
                autoText.setAdapter(null);
                autoText.setAdapter(adapter);
                autoText.showDropDown();
                Log.i("UPDATE","showDropDown");
            }
            super.onPostExecute(aVoid);
        }
    }
}

编辑2 我也尝试了这个方法，但仍然没有成功。下拉菜单只在按下退格键时才显示...

@Override
public void afterTextChanged(Editable editable) {
    runOnUiThread(updateAdapter);
}

...

private Runnable updateAdapter = new Runnable() {

    public void run(){
        Log.i("ADAPTER_UPDATE","start");
        adapter.notifyDataSetChanged();
        autoText.showDropDown();
        Log.i("ADAPTER_UPDATE","end");
    }
};

注意 问题是：我输入一个地址，但是没有任何显示。但是在logcat中，我看到适配器已经更新了。但是下拉菜单没有显示出来。然后当我删除一个字符时，下拉菜单就会显示出来？！

你可以尝试adapter.setNotifyOnChange(false)，然后在onPostExecute()结束时手动调用adapter.notifyDataSetChanged()。 - Dan Brough
我刚试了一下，它不起作用... - Christos Baziotis
2个回答
10

看起来你确实需要实现一个筛选器：

import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import android.widget.Button;
import android.widget.Filter;
import android.widget.TextView;

public class TestDoctor extends Activity {

  TextView latText;
  TextView lngText;
  AutoCompleteTextView autoText;
  ArrayAdapter<String> adapter;
  private Filter filter;
  private static final int ADDRESS_TRESHOLD = 10;

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

    latText = (TextView) findViewById(R.id.latTextView);
    lngText = (TextView) findViewById(R.id.longTextView);
    autoText = (AutoCompleteTextView) findViewById(R.id.autoCompleteTextView);

    Button button = (Button) findViewById(R.id.buttonDoctor);
    button.setOnClickListener(new Button.OnClickListener() {
      public void onClick(View v) {
        new AdapterUpdaterTask().execute();
      }
    });

    autoText.setThreshold(ADDRESS_TRESHOLD);
    autoText.setHint("Οδός Αριθμός, Περιοχή");

    filter = new Filter() {
      @Override
      protected void publishResults(CharSequence constraint,
          FilterResults results) {
      }

      @Override
      protected FilterResults performFiltering(CharSequence constraint) {
        Log.i("Filter",
            "Filter:" + constraint + " thread: " + Thread.currentThread());
        if (constraint != null && constraint.length() > ADDRESS_TRESHOLD) {
          Log.i("Filter", "doing a search ..");
          new AdapterUpdaterTask().execute();
        }
        return null;
      }
    };

    adapter = new ArrayAdapter<String>(this,
        android.R.layout.simple_dropdown_item_1line) {
      public android.widget.Filter getFilter() {
        return filter;
      }
    };

    autoText.setAdapter(adapter);
    adapter.setNotifyOnChange(false);
  }

  @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 List<SimpleAddress> getAddressesFromText(String address) {
    address = address.replace(' ', '+');
    HttpHelper httpHelper = new HttpHelper();
    InputStream inputStream = httpHelper
        .makeHttpGetRequest("http://maps.google.com/maps/api/geocode/json?address="
            + address + "&sensor=false");
    String response = httpHelper.inputStreamToString(inputStream);

    List<SimpleAddress> simpleAddresses = new ArrayList<SimpleAddress>();
    try {
      JSONObject jsonObject = new JSONObject(response);

      int size = ((JSONArray) jsonObject.get("results")).length();

      for (int i = 0; i < size; i++) {
        String formatted_address = ((JSONArray) jsonObject.get("results"))
            .getJSONObject(i).getString("formatted_address");

        Double lng = ((JSONArray) jsonObject.get("results")).getJSONObject(i)
            .getJSONObject("geometry").getJSONObject("location")
            .getDouble("lng");

        Double lat = ((JSONArray) jsonObject.get("results")).getJSONObject(i)
            .getJSONObject("geometry").getJSONObject("location")
            .getDouble("lat");
        simpleAddresses.add(i, new SimpleAddress(formatted_address, lat, lng));
      }
      return simpleAddresses;
    } catch (JSONException e) {
      return null;
    }
  }

  public class AdapterUpdaterTask extends AsyncTask<Void, Void, Void> {
    List<SimpleAddress> simpleAddresses = new ArrayList<SimpleAddress>();

    @Override
    protected Void doInBackground(Void... voids) {
      Log.i("UPDATE", "1");
      try {
        simpleAddresses = getAddressesFromText(autoText.getText().toString());
      } catch (NullPointerException e) {
      }
      Log.i("UPDATE", "2");
      return null;
    }

    @Override
    protected void onPostExecute(Void aVoid) {
      Log.i("UPDATE", "3");

      int size = simpleAddresses.size();

      if (size > 0) {
        adapter.clear();
        Log.i("ADAPTER_SIZE", "" + size);
        for (int i = 0; i < size; i++) {
          adapter.add(simpleAddresses.get(i).getFormatted_address());
          Log.i("ADDED", simpleAddresses.get(i).getFormatted_address());
        }
        Log.i("UPDATE", "4");

        adapter.notifyDataSetChanged();
        autoText.showDropDown();

      }
      super.onPostExecute(aVoid);
    }
  }

}
1
您还应确保一次只执行一个搜索，并且在输入时有小延迟后才执行搜索。 - Dan Brough
抱歉，请问您是如何设置延迟以在开始过滤之前确保仅执行一次搜索的？我无法理解... - tonix
1
@user3019105 使用一个处理程序：http://developer.android.com/reference/android/os/Handler.html - Dan Brough
谢谢您的回复，很抱歉我是Android的新手，是否有指南或类似的东西可以展示如何在autocompletetextview中特别使用Handler，因为我阅读了您在评论中发布的指南，但没有找到如何在这种情况下使用它们... 再次感谢！ - tonix
您可以使用处理程序在特定线程上处理消息。您可以删除任何现有的消息，然后排队等待稍后发送的消息。这可以通过sendMessageDelayed和removeMessages处理程序方法来完成。 - Dan Brough
显示剩余4条评论
3
可能与在主线程中未调用autoText.showDropDown()有关。也许你可以尝试改为以下方式：
autoText.getHandler().post(new Runnable() {
    @Override
    public void run() {
        autoText.showDropDown();
    }
})
我并不是只想在OnCreate中添加它，而是要使用我发布的代码代替autoText.showDropDown()。所以无论何时需要执行该操作，都请使用我发布的代码。 - Ivo
还是一样的问题...我不明白。这太令人沮丧了。 - Christos Baziotis
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