问安卓AutoCompleteTextView DropDown位置

EN

package com.example.autocomplete;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;

public class MainActivity extends Activity {
     protected void onCreate(Bundle icicle) {
         super.onCreate(icicle);
         setContentView(R.layout.activity_main);

         ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
                 android.R.layout.simple_list_item_1, COUNTRIES);
         AutoCompleteTextView textView = (AutoCompleteTextView)
                 findViewById(R.id.countries_list);
         textView.setAdapter(adapter);
     }

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

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${relativePackage}.${activityClass}" >

    <AutoCompleteTextView
        android:id="@+id/countries_list"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="100dp"
        android:dropDownHeight="100dp"
        android:ems="10"
        android:text="AutoCompleteTextView" >

        <requestFocus />
    </AutoCompleteTextView>

</RelativeLayout>