activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context="com.example.aluno.provathiago.MainActivity"
    android:weightSum="1">

    <AutoCompleteTextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/lista"
        android:hint="@string/digitealgo"/>

    <android.support.v7.widget.Toolbar
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="?attr/colorPrimary"
        android:theme="?attr/actionBarTheme"
        android:minHeight="?attr/actionBarSize"
        android:id="@+id/toolbar"
        android:layout_weight="0.18" />

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/nome"
        android:hint="Digite algo para adicionar"/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="addNome"
        android:text="INCLUIR"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:onClick="excNome"
        android:text="EXCLUIR"/>
</LinearLayout>