XML属性

android:completionHint 下拉菜单标题
android:completionThreshold 输入多少个字符才会提示
android:dropDownHerght 下拉菜单高度
android:dropDownWidth 下拉菜单宽度
android:dropDownHorizontalOffset 下拉菜单与文本的水平偏移量。默认为对齐文本框
android:dropDownVerticalOffset 下拉菜单与文本的垂直偏移量。默认紧跟文本框
android:popupBackground 下拉菜单设置背景

列子

1.布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
  xmlns:android="http://schemas.android.com/apk/res/android"    
  android:orientation="horizontal"     
  android:layout_width="match_parent"   
  android:layout_height="match_parent"                    >    
<AutoCompleteTextView        
  android:id="@+id/av"        
  android:layout_width="wrap_content"        
  android:layout_height="wrap_content"        
  android:hint="请输入搜索内容"        
  android:layout_weight="7"        
  android:completionThreshold="2"        
  android:text=""        
/>    
<Button        
  android:layout_weight="1"        
  android:text="搜索"        
  android:id="@+id/bn"        
  android:layout_width="wrap_content"        
  android:layout_height="wrap_content"        
/>
</LinearLayout>

2.Activity

public class MainActivity extends AppCompatActivity {
    private static final String[] name = {"有空you","淘宝天猫","美的电器部门", 
           "软件编程java","LG显示器","哈哈哈哈哈哈哈"};
    private AutoCompleteTextView av;
    private Button bn;
    private ArrayAdapter adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);
        av = (AutoCompleteTextView) findViewById(R.id.av);
        bn = (Button) findViewById(R.id.bn);
        adapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1,name);
        av.setAdapter(adapter);
        bn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(MainActivity.this, av.getText().toString(), Toast.LENGTH_SHORT).show();
            }
        });
    }
}