AutoCompleteTextView有時顯示的建議，但有時不

Question

AutoCompleteAdapter類：

public class AutoCompleteAdapter extends ArrayAdapter<String> { 

    private LayoutInflater inflater; 
    private List<String> mData; 
    private int resourceId; 

    public AutoCompleteAdapter(Context context, int textViewResourceId, 
      List<String> objects) {  
     super(context, textViewResourceId, objects); 

     inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
     mData = objects; 
     resourceId = textViewResourceId; 
    } 


    @Override 
    public View getView(int position, View convertView, ViewGroup parent) { 

     TextView textView; 

     if (convertView == null){ 
      convertView = inflater.inflate(resourceId, null); 

     } 

     textView = (TextView)convertView.findViewById(R.id.textView1); 
     textView.setText(mData.get(position)); 

     System.out.println("getView:" + mData); 
     return convertView; 
    } 

    @Override 
    public Filter getFilter() { 
     Filter custom_filter = new Filter() { 
      @Override 
      protected FilterResults performFiltering(CharSequence constraint) { 
       FilterResults f = new FilterResults(); 

       ArrayList<String> matchItems = new ArrayList<String>(); 
       if (constraint != null){ 
        for (String item : MainActivity.COUNTRIES){ 
         if (item.toLowerCase().contains(constraint.toString().toLowerCase())){/////if contain the string 
          matchItems.add(item); 

         } 
        }        
       } 
       f.values = matchItems; 
       return f; 
      } 

      @Override 
      protected void publishResults(CharSequence constraint, FilterResults results) { 

       ArrayList<String> matchItems = (ArrayList<String>) results.values; 
       mData.clear(); 
       mData.addAll(matchItems); 
       System.out.println("publishResults ===" + mData); //data can be printed out here every time 

       notifyDataSetChanged(); 

      } 
     }; 
     return custom_filter; 
    } 
} 

MainActivity類別：

public class MainActivity extends Activity { 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     AutoCompleteAdapter adapter = new AutoCompleteAdapter(this, R.layout.row, new ArrayList<String>()); 
     final AutoCompleteTextView textView = (AutoCompleteTextView) 
       findViewById(R.id.autoCompleteTextView1);   
     textView.setAdapter(adapter); 

    } 
    public static final String[] COUNTRIES = new String[] { 
     "Belgium", "France", "Italy", "Germany", "Spain" 
    };  
} 

activity_main.xml中：

<AutoCompleteTextView 
     android:id="@+id/autoCompleteTextView1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:layout_alignParentTop="true" 
     android:layout_alignRight="@+id/abc" 
     android:layout_marginRight="16dp" 
     android:layout_marginTop="50dp" 
     android:ems="10" 
     android:text="" 
     android:completionThreshold="1" 
     android:textColor="@android:color/black" 
     android:textColorHint="@android:color/black"> 
     <requestFocus /> 
</AutoCompleteTextView> 

row.xml：

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical" > 

    <TextView 
     android:id="@+id/textView1" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:text="" 
     android:textAppearance="?android:attr/textAppearanceMedium" /> 

</LinearLayout> 

現在我的名單是「比利時」，「法國」，「意大利」，「德國」，「西班牙」，如果我輸入「馬」，「德」將在下拉列表顯示，但當我再輸入一個字符「n」變成「man」時，下拉消失，此後，如果我繼續輸入一個字符「y」變爲「多」，則「德國」再次顯示。即使找到匹配，AutoCompleteTextView的下拉菜單也會顯示開啓和關閉狀態。我的代碼有什麼問題？

Answer 1

// try this 

**activity_main.xml** 
<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
     xmlns:android="http://schemas.android.com/apk/res/android" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content"> 

    <AutoCompleteTextView 
      android:id="@+id/autoComplete" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content"/> 
</LinearLayout> 

**auto_complete_list-item.xml** 
<?xml version="1.0" encoding="utf-8"?> 
<TextView xmlns:android="http://schemas.android.com/apk/res/android" 
    android:padding="5dp" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" /> 

**MainActivity** 
public class MainActivity extends Activity { 

    private AutoCompleteTextView autoComplete; 
    public static final String[] COUNTRIES = new String[] { 
      "Belgium", "France", "Italy", "Germany", "Spain" 
    }; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     autoComplete = (AutoCompleteTextView) findViewById(R.id.autoComplete); 
     autoComplete.setAdapter(new PlacesAutoCompleteAdapter(this, R.layout.auto_complete_list_item)); 

     autoComplete.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
      @Override 
      public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) { 
       String str = (String) adapterView.getItemAtPosition(position); 
       autoComplete.setText(str); 
      } 
     }); 
    } 

    private class PlacesAutoCompleteAdapter extends ArrayAdapter<String> implements Filterable { 
     private ArrayList<String> resultList; 

     public PlacesAutoCompleteAdapter(Context context, int textViewResourceId) { 
      super(context, textViewResourceId); 
     } 

     @Override 
     public int getCount() { 
      return resultList.size(); 
     } 

     @Override 
     public String getItem(int index) { 
      return resultList.get(index); 
     } 

     @Override 
     public Filter getFilter() { 
      Filter filter = new Filter() { 
       @Override 
       protected FilterResults performFiltering(final CharSequence constraint) { 
        final FilterResults filterResults = new FilterResults(); 
        if (constraint != null) { 
         // Retrieve the autocomplete results. 
         ArrayList<String> matchList = new ArrayList<String>(); 
         for (int i =0;i<COUNTRIES.length;i++){ 
          if(COUNTRIES[i].toLowerCase().contains(constraint)){ 
           matchList.add(COUNTRIES[i]); 
          } 
         } 
         resultList = matchList; 
         filterResults.values = resultList; 
         filterResults.count = resultList.size(); 
        } 
        return filterResults; 

       } 

       @Override 
       protected void publishResults(CharSequence constraint, FilterResults results) { 
        if (results != null && results.count > 0) { 
         notifyDataSetChanged(); 
        } else { 
         notifyDataSetInvalidated(); 
        } 
       } 
      }; 
      return filter; 
     } 
    } 

}