＆＃34;错过了没有参数的构造函数＆＃34;尽管给了一个没有参数的构造函数

Question

  

E / AndroidRuntime（31431）：   com.google.firebase.database.DatabaseException：Class   com.google.firebase.quickstart.database.models.Video $ Snippet是   错过了没有参数的构造函数

显然，我已经为类Snippet提供了一个没有参数的构造函数：

package com.google.firebase.quickstart.database.models;

import com.google.firebase.database.Exclude;
import com.google.firebase.database.IgnoreExtraProperties;

import java.util.HashMap;
import java.util.Map;

@IgnoreExtraProperties
public class Video {

    public String id;
    public String parsedUrl;
    public String rawUrl;
    public int starCount = 0;
    public Snippet snippet;
    public Map<String, Boolean> stars = new HashMap<>();

    public Video() {
        // Default constructor required for calls to DataSnapshot.getValue(Post.class)
    }

    public Video(String uid, String author, String title, String body) {
        this.id = id;
        this.parsedUrl = parsedUrl;
        this.rawUrl = rawUrl;
    }

    public class Snippet {
        public String categoryId;
        public String channelId;
        public String channelTitle;
        public String defaultAudioLanguage;
        public String description;
        public String liveBroadcastContent;
        public String publishedAt;
        public String title;
        public String[] tags;
        public Snippet snippet;
        public Localised localised;
        public Thumbnail thumbnail;

        public String getCategoryId() {
            return categoryId;
        }

        public String getChannelId() {
            return channelId;
        }

        public String getChannelTitle() {
            return channelTitle;
        }

        public String getDefaultAudioLanguage() {
            return defaultAudioLanguage;
        }

        public String getLiveBroadcastContent() {
            return liveBroadcastContent;
        }

        public String getPublishedAt() {
            return publishedAt;
        }

        public String getTitle() {
            return title;
        }

        public Snippet() {
            // Default constructor required for calls to DataSnapshot.getValue(User.class)
        }

        public Snippet(String categoryId,
                       String channelId,
                       String channelTitle,
                       String defaultAudioLanguage,
                       String description,
                       String liveBroadcastContent,
                       String publishedAt,
                       String title,
                       String[] tags) {
            this.categoryId = categoryId;
            this.channelId = channelId;
            this.channelTitle = channelTitle;
            this.defaultAudioLanguage = defaultAudioLanguage;
            this.description = description;
            this.liveBroadcastContent = liveBroadcastContent;
            this.publishedAt = publishedAt;
            this.title = title;
            for (int i = 0; i != tags.length; i++) {
                this.tags[i] = tags[i];
            }
        }

        public class Localised {
            public String description;
            public String title;

            public Localised() {
                // Default constructor required for calls to DataSnapshot.getValue(User.class)
            }

            public Localised(String description,
                             String title) {
                this.description = description;
                this.title = title;
            }

            public String getDescription() {
                return description;
            }

            public String getTitle() {
                return title;
            }
        }

        public class Thumbnail {
            public Maxres maxres;
            public Standard standard;

            public Thumbnail() {
                // Default constructor required for calls to DataSnapshot.getValue(User.class)
            }

            public Thumbnail(Maxres maxres,
                             Standard standard) {
                this.maxres = maxres;
                this.standard = standard;
            }

            public class Maxres {
                public String height;
                public String url;
                public String width;

                public Maxres() {
                    // Default constructor required for calls to DataSnapshot.getValue(User.class)
                }
                public Maxres(String height,
                              String url,
                              String width) {
                    this.height = height;
                    this.url = url;
                    this.width = width;
                }

                public String getHeight() {
                    return height;
                }

                public String getUrl() {
                    return url;
                }

                public String getWidth() {
                    return width;
                }
            }

            public class Standard {
                public String height;
                public String url;
                public String width;

                public Standard() {
                    // Default constructor required for calls to DataSnapshot.getValue(User.class)
                }
                public Standard(String height,
                                String url,
                                String width) {
                    this.height = height;
                    this.url = url;
                    this.width = width;
                }
                public String getUrl() {
                    return url;
                }
            }

            public Maxres getMaxres() {
                return maxres;
            }

            public Standard getStandard() {
                return standard;
            }
        }

        public Thumbnail getThumbnail() {
            return thumbnail;
        }
    }

    public Snippet getSnippet() {
        return snippet;
    }

    public void setSnippet(Snippet snippet) {
        this.snippet = snippet;
    }
}