java - 如何分包自定义arraylist？

Question

我有两个实现 Parcelable 的类。我必须将其中一个的对象写入列表。
第一个模型:

public class Challenge implements Parcelable {

    private long id;
    @JsonProperty("max_volume")
    private int maxVolume;
    @JsonProperty("current_volume")
    private int currentVolume;
    private String name;
    private String description;
    @JsonProperty("max_count")
    private int maxCount;
    @JsonProperty("date_from")
    private Date dateFrom;
    @JsonProperty("date_to")
    private Date dateTo;
    @JsonProperty("create_time")
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd HH:mm ZZZZ")
    private Date createTime;
    private ChallengeStatus status;
    @JsonProperty("update_date")
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd HH:mm ZZZZ")
    private Date updateTime;
    private ChallengeCategory category;
    private Subject subject;
    private ArrayList<User> userArrayList;
    private int practice;


    public double getProgress() {
        return progress;
    }

    public void setProgress(double progress) {
        this.progress = progress;
    }

    public int getPractice() {
        return practice;
    }

    public void setPractice(int practice) {
        this.practice = practice;
    }

    private double progress;

    public Challenge() {
    }

    private Creator<User> creator;

    protected Challenge(Parcel in) {
        id = in.readLong();
        maxVolume = in.readInt();
        currentVolume = in.readInt();
        name = in.readString();
        description = in.readString();
        maxCount = in.readInt();
//        dateFrom = new Date(in.readLong());
//        dateTo = new Date(in.readLong());
//        createTime = new Date(in.readLong());
//        status = ChallengeStatus.getEnum(in.readString());
//        updateTime = new Date(in.readLong());
//        category = ChallengeCategory.getEnum(in.readString());
        subject = in.readParcelable(Subject.class.getClassLoader());
        userArrayList = in.readTypedList(userArrayList, User.CREATOR);
    }

    public static final Creator<Challenge> CREATOR = new Creator<Challenge>() {
        @Override
        public Challenge createFromParcel(Parcel in) {
            return new Challenge(in);
        }

        @Override
        public Challenge[] newArray(int size) {
            return new Challenge[size];
        }
    };

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public int getMaxVolume() {
        return maxVolume;
    }

    public void setMaxVolume(int maxVolume) {
        this.maxVolume = maxVolume;
    }

    public int getCurrentVolume() {
        return currentVolume;
    }

    public void setCurrentVolume(int currentVolume) {
        this.currentVolume = currentVolume;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public int getMaxCount() {
        return maxCount;
    }

    public void setMaxCount(int maxCount) {
        this.maxCount = maxCount;
    }

    public Date getDateFrom() {
        return dateFrom;
    }

    public void setDateFrom(Date dateFrom) {
        this.dateFrom = dateFrom;
    }

    public Date getDateTo() {
        return dateTo;
    }

    public void setDateTo(Date dateTo) {
        this.dateTo = dateTo;
    }

    public Date getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Date createTime) {
        this.createTime = createTime;
    }

    public ChallengeStatus getStatus() {
        return status;
    }

    public void setStatus(ChallengeStatus status) {
        this.status = status;
    }

    public Date getUpdateTime() {
        return updateTime;
    }

    public void setUpdateTime(Date updateTime) {
        this.updateTime = updateTime;
    }

    public ChallengeCategory getCategory() {
        return category;
    }

    public void setCategory(ChallengeCategory category) {
        this.category = category;
    }

    public Subject getSubject() {
        return subject;
    }

    public void setSubject(Subject subject) {
        this.subject = subject;
    }

    @Override
    public int describeContents() {
        return 0;
    }

    public ArrayList<User> getUserArrayList() {
        return userArrayList;
    }

    public void setUserArrayList(ArrayList<User> userArrayList) {
        this.userArrayList = userArrayList;
    }

    public static Creator<Challenge> getCREATOR() {
        return CREATOR;
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeLong(id);
        dest.writeInt(maxVolume);
        dest.writeInt(currentVolume);
        dest.writeString(name);
        dest.writeString(description);
        dest.writeInt(maxCount);
//        dest.writeLong(dateFrom.getTime());
//        dest.writeLong(dateTo.getTime());
//        dest.writeLong(createTime.getTime());
//        dest.writeString(status.toString());

//        dest.writeLong(updateTime.getTime());
//        dest.writeString(category.toString());
        dest.writeParcelable(subject, flags);
        dest.writeTypedList(userArrayList);
    }
}

我在这一行遇到问题: userArrayList = in.readTypedList(userArrayList, User.CREATOR);
它看起来像这样:
第二个模型的示例:

public class User implements Parcelable {
    long id;
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd HH:mm ZZZZ")
    Date time;
    String image_src;
    String first_name;
    String last_name;

    public User() {

    }

    public String getFirst_name() {
        return first_name;
    }

    public void setFirst_name(String first_name) {
        this.first_name = first_name;
    }

    public String getLast_name() {
        return last_name;
    }

    public void setLast_name(String last_name) {
        this.last_name = last_name;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public Date getTime() {
        return time;
    }

    public void setTime(Date time) {
        this.time = time;
    }

    public String getImage_src() {
        return image_src;
    }

    public void setImage_src(String image_src) {
        this.image_src = image_src;
    }

    protected User(Parcel parcel) {
        id = parcel.readLong();
        time = new Date(parcel.readLong());
        image_src = parcel.readString();
        first_name = parcel.readString();
        last_name = parcel.readString();
    }

    public static final Creator<User> CREATOR = new Creator<User>() {
        @Override
        public User createFromParcel(Parcel in) {
            return new User(in);
        }

        @Override
        public User[] newArray(int size) {
            return new User[size];
        }
    };

    public static Creator<User> getCREATOR() {
        return CREATOR;
    }

    @Override
    public int describeContents() {
        return 0;
    }

    @Override
    public void writeToParcel(Parcel parcel, int i) {
        parcel.writeLong(id);
//        parcel.writeLong(time.getTime());
        parcel.writeString(image_src);
        parcel.writeString(first_name);
        parcel.writeString(last_name);
    }
}

你能帮我找出我的错误吗？

Answer 1

使用前必须初始化userArrayList:

userArrayList = new ArrayList<User>();
in.readTypedList(userArrayList, User.CREATOR);