自动完成文本框AutoCompleteTextView

        android:completionHint="comhint" //设置下拉框提示标题
        android:completionThreshold="1"  //至少输入1个字符出现提示
        android:dropDownAnchor="@id/btn_s" //以某个控件定位，不填默认自己
        android:dropDownWidth="300dp" //下拉框宽度
        android:dropDownHeight="match_parent" //下拉框高度

        auto.setCompletionHint("aa");
        auto.setThreshold(1);
        auto.setDropDownAnchor(R.id.d);
        auto.setDropDownWidth(400);
        auto.setDropDownHeight(400);

        String[] str =  new String[]{
                "aaa",
                "bbb",
                "bbb",
                "bbb",
                "bbb",
                "ccc",
                "ddd",
                "ddd"
        };

        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,str);
        setAdapter(adapter);