public class isLightningUser {
    public static Boolean isLightningUser(){
        return [SELECT Profile.PermissionsLightningExperienceUser FROM User WHERE Id = :UserInfo.getUserId()].Profile.PermissionsLightningExperienceUser;
    }
    public static void sample(){
    	if( isLightningUser() ) {
    		// Do something for Lightning Experience
	}
	else {
    		// Use classic
	}
    }
}