<AutoCompleteTextView
    android:id="@+id/autocomplete_country"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_marginLeft="5dp"
  />

<?xml version="1.0" encoding="utf-8"?>
<TextView
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:padding="10dp"
  android:textSize="16sp"
  android:textColor="#000">
</TextView>

public void setAutoCompleteTextView(){
  autoCompleteTextView = (AutoCompleteTextView)findViewById(R.id.autocomplete_country);
  //COUNTRIES是一个数组，AutoCompleteTextView会将数组内容和用户输入的匹配，然后再显示出来提示用户
  //R.layout.list_item显示的是提示信息显示的内容的样式
  ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this, R.layout.list_item, COUNTRIES);
  autoCompleteTextView.setAdapter(arrayAdapter);
}