Android This Activity already has an action bar supplied by the window decor

This Activity already has an action bar supplied by the window decor. Do not request Window.FEATURE_ACTION_BAR and set windowActionBar to false in your theme to use a Toolbar instead.

解决方式：

打开Style，设置为

<style name="AppTheme" parent="AppTheme.Base" />

<style name="AppTheme.Base" parent="Theme.AppCompat.Light.NoActionBar">
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="android:windowNoTitle">true</item>
    <item name="windowActionBar">false</item>
</style>
<style name="AppTheme.NoActionBar">
    <item name="android:windowActionBar">false</item>
    <item name="windowActionBar">false</item>
    <item name="windowNoTitle">true</item>
    <item name="android:windowNoTitle">true</item>
</style>