1 清单文件中application中引入主题 android:theme=“@style/AppTheme”

<application
        android:name=".MyApp"
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme"
        android:usesCleartextTraffic="true"
        tools:replace="android:allowBackup">

2自定义style,主要是这个属性：@color/blue

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        
        <item name="colorPrimary">@color/colorPrimaryitem>
        <item name="colorPrimaryDark">@color/blueitem>
        <item name="colorAccent">@color/colorAccentitem>
        <item name="textAllCaps">falseitem>

    style>