java碎片

// UserService.java
public class UserService {
    public interface UserTemplate{
        User createUser(int id);
    }

    public static List<User> userList(ArrayList<Integer> ids,UserTemplate userTemplate){

        if(ids == null || ids.size() < 1){
            return null;
        }

        List<User> users = new ArrayList<>();

        Iterator<Integer> it = ids.iterator();
        while(it.hasNext()){
            users.add(userTemplate.createUser(it.next()));
        }

        return users;
    }
}

// UserTemplateImpl.java
public class UserTemplateImpl {

    public static Icon userIcon(String iconString){
        //...
    }

    public static String userName(int uid,String name){
        //...
    }

    /**
     * 只显示用户的 id/昵称/头像
     */
    public static class userInfoLite implements UserService.UserTemplate {

        @Override
        public User createUser(int id) {
            UserLite userLite = UserService.getUserLiteInfo(id);
            return new User(id,userName(id,userLite.getName()),userIcon(userLite.getIcon()));
        }
    }

}

UserService.userList(ids, new UserTemplateImpl.userInfoLite())