读写一个包含可传递对象的ArrayList of ArrayLists到Intent中。

Question

我刚刚把项目中所有可序列化的类都改为可包裹的类。除了一个由一个 ArrayList 包含另一个 ArrayList 的类之外，一切正常。我已经进行了调试。写入这个 ArrayList 时没有错误。但是在读取时出现了错误。

这是出错的类：

public class Timetable implements Parcelable
{
private int actLap = 0;
private ArrayList<Lap> timetable;
private ArrayList<Location> loggedLocations;
private Date startTime; ...
...
public void writeToParcel(Parcel out, int flags)
{
    out.writeInt(actLap);
    out.writeTypedList(timetable); //no error here
    out.writeTypedList(loggedLocations); ...
...
    private Timetable(Parcel in)
{
    actLap          = in.readInt();
    in.readTypedList(timetable, Lap.CREATOR); //error after this line
    in.readTypedList(loggedLocations, Location.CREATOR);
    startTime       = (Date)in.readSerializable();
    bestLap         = in.readParcelable(Lap.class.getClassLoader());
    track           = in.readParcelable(Track.class.getClassLoader());
    description     = in.readString();
}

以下是其他课程的列表：

public class Lap implements Parcelable
{   
private ArrayList<Time> sectorTimes = new ArrayList<Time>();
private Time laptime; ...
...
public void writeToParcel(Parcel out, int flags)
{
    out.writeTypedList(sectorTimes);
    out.writeParcelable(laptime,flags);
}

public static final Parcelable.Creator<Lap> CREATOR = new Parcelable.Creator<Lap>()
{
    public Lap createFromParcel(Parcel in)
    {
        return new Lap(in);
    }

    public Lap[] newArray(int size)
    {
        return new Lap[size];
    }
};

private Lap(Parcel in)
{
    in.readTypedList(sectorTimes, Time.CREATOR);
    laptime     = in.readParcelable(Time.class.getClassLoader());
}

而这个类：

public class Time implements Parcelable
{
private long timeLong;
private String timeString;...
...
public void writeToParcel(Parcel out, int flags)
{
    out.writeLong(timeLong);
    out.writeString(timeString);
}

public static final Parcelable.Creator<Time> CREATOR = new Parcelable.Creator<Time>()
{
    public Time createFromParcel(Parcel in)
    {
        return new Time(in);
    }

    public Time[] newArray(int size)
    {
        return new Time[size];
    }
};

private Time(Parcel in)
{
    timeLong = in.readLong();
    timeString = in.readString();
}

就像我之前所说的那样，一切都运行良好（包括通过意图传递的更多Parcelable类（包括单个ArrayList）和保存在文件中的Parcelable类）。 那么你们能帮我写和读取那个双重ArrayList吗？ 提前致谢。

- Hömafreak

Answer 1

如果您的代码如上所述，那么您只需要初始化ArrayLists，例如。

private Timetable(Parcel in)
{
    // readTypeList() needs an existing List<> to load.
    timetable = new ArrayList<Lap>();
    loggedLocations = new ArrayList<Location>();

    actLap          = in.readInt();
    in.readTypedList(timetable, Lap.CREATOR);
    in.readTypedList(loggedLocations, Location.CREATOR);
    ...

- matiash

---

谢谢！这解决了我的问题。我原本以为这个方法会创建一个新的ArrayList。 - Hömafreak

非常感谢您的分享。太棒了！ - Victor Viola