跟踪

android:theme="@style/AppTheme"

进入修改style.xml文件，这里还可以修改颜色，还可以全屏

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.NoActionBar">
        <!-- Customize your theme here. -->
        <!--<item name="colorPrimary">@color/colorPrimary</item>-->
        <!--<item name="colorPrimaryDark">@color/colorPrimaryDark</item>-->
        <!--<item name="colorAccent">@color/colorAccent</item>-->
        <item name="android:windowFullscreen">true</item>
    </style>

</resources>