向JDA中提到的用户添加角色

import net.dv8tion.jda.api.entities.Guild;
import net.dv8tion.jda.api.entities.Member;
import net.dv8tion.jda.api.entities.Role;
import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
import net.dv8tion.jda.api.hooks.ListenerAdapter;

public class RoleAdder extends ListenerAdapter {
    @Override
    public void onMessageReceived(MessageReceivedEvent event) {
        if (event.getMessage().getContentRaw().equalsIgnoreCase("!addrole @user")) {
            Guild guild = event.getGuild();
            Member member = event.getMessage().getMentionedMembers().get(0);
            Role role = guild.getRolesByName("CustomRole", true).get(0);

            if (role != null) {
                guild.addRoleToMember(member, role).queue();
                event.getChannel().sendMessage("角色已成功添加！").queue();
            } else {
                event.getChannel().sendMessage("未找到指定角色！").queue();
            }
        }
    }
}