无法写入/读取带有对象列表的文件

Question

我试图将对象列表保存到文件中，但是每当我尝试从文件中读取文件时，它总是失败。 有人可以告诉我我在做什么错

写给它

public void writeToFile(List<EventsClass> list)
{
    String filename = "events.srl";
    ObjectOutput out = null;

    try
    {
        out = new ObjectOutputStream(new FileOutputStream(new File(getFilesDir(),"")+File.separator+filename));
        out.writeObject(list);
        out.close();
    }
    catch (IOException e)
    {
        e.printStackTrace();
    }
}

我检查了，参数列表总是包含对象列表

从中读

public List<EventsClass> readFromFile()
{
    ObjectInputStream input;
    String filename = "events.srl";

    try
    {
        input = new ObjectInputStream(new FileInputStream(new File(new File(getFilesDir(),"")+File.separator+filename)));
        List<EventsClass> list = (List<EventsClass>) input.readObject();
        input.close();
        return list;
    }
    catch (IOException | ClassNotFoundException e)
    {
        e.printStackTrace();
        return null;
    }
}

它总是无法读取文件并返回null

这是EventsClass

public class EventsClass
{
    private String eventName;
    private String eventClass;
    private String eventDate;
    private int eventMonth;
    private int eventDay;

    public EventsClass(String eventClass, String eventName, String eventDate, int eventMonth, int eventDay)
    {
        this.eventClass = eventClass;
        this.eventName = eventName;
        this.eventDate = eventDate;
        this.eventMonth = eventMonth;
        this.eventDay = eventDay;
    }

    public void putEventData(String mClass, String name, String date, int month, int day)
    {
        this.eventClass = mClass;
        this.eventName = name;
        this.eventDate = date;
        this.eventMonth = month;
        this.eventDay = day;
    }

    public String getEventClass()
    {
        return eventClass;
    }

    public String getEventName()
    {
        return eventName;
    }

    public String getEventDate()
    {
        return eventDate;
    }

    public int getEventMonth()
    {
        return eventMonth;
    }

    public int getEventDay()
    {
        return eventDay;
    }
}

Answer 1

是的，EventsClass需要可序列化才能写入存储。 如果您实现了java.io.Serializable ，那么所有这些都应该对您有效。 这是一个不错的教程，您可以了解有关Java序列化的更多信息。