Android

// The theme ID is 0 for the Light theme, 1 for the Lively theme, and 2 for the Serious theme.
TUIThemeManager.getInstance().changeTheme(context, themeID);
System.exit(0);
Intent intent = context.getPackageManager().getLaunchIntentForPackage(context.getPackageName());
context.startActivity(intent);

mArrowImageView.setBackgroundResource(TUIThemeManager.getAttrResId(getContext(), R.attr.chat_jump_recent_down_icon));

replyContentTv.setTextColor(resources.getColor(TUIThemeManager.getAttrResId(context, R.attr.chat_other_reply_text_color))); 

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="ring"
    android:innerRadius="22.5dp"
    android:thickness="1.5dp"
    android:useLevel="false">

    <solid android:color="?attr/core_primary_color" />
</shape>

<ImageView
    android:id="@+id/demo_login_theme_arrow"
    android:layout_width="9.6dp"
    android:layout_height="9.6dp"
    android:layout_gravity="center"
    android:background="?attr/demo_login_language_arrow" />

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <style name="TUIChatEnterpriseTheme" parent="TUIBaseEnterpriseTheme">
        <item name="chat_bubble_self_bg">@drawable/chat_bubble_self_bg_enterprise</item>
        <item name="chat_bubble_other_bg">@drawable/chat_bubble_other_bg_enterprise</item>
        <item name="chat_input_area_bg">@color/chat_input_layout_bg_enterprise</item>
        <item name="chat_unread_dot_bg_color">@color/chat_unread_dot_bg_color_enterprise</item>
        <item name="chat_unread_dot_text_color">?attr/core_primary_color</item>
        <item name="chat_title_bar_more_menu">@drawable/chat_title_bar_more_menu_enterprise</item>
        <item name="chat_other_msg_text_color">@color/chat_other_msg_text_color_enterprise</item>

        ...

    </style>
</resources>

android {
    ...
    // Theme resourcce folder
    sourceSets {
        main {
            res.srcDirs += "src/main/res-light"
            res.srcDirs += "src/main/res-lively"
            res.srcDirs += "src/main/res-serious"
            res.srcDirs += "src/main/res-enterprise"
        }
    }
}

public class DemoApplication extends Application {
    @Override
    public void onCreate() {
        int enterpriseThemeID = 3;
        TUIThemeManager.addTheme(enterpriseThemeID, R.style.DemoEnterpriseTheme);
        TUIThemeManager.addTheme(enterpriseThemeID, R.style.TUIChatEnterpriseTheme);
        TUIThemeManager.addTheme(enterpriseThemeID, R.style.TUIContactEnterpriseTheme);
        TUIThemeManager.addTheme(enterpriseThemeID, R.style.TUIGroupEnterpriseTheme);
        // Switch a theme
        TUIThemeManager.getInstance().changeTheme(this, enterpriseThemeID);
    }
}