NotSerializable异常发生在不应该发生的地方

Question

我已经使用Java几个月了，我对它还是相当陌生，所以任何帮助都很感激。我一直致力于一款游戏(基于另一款游戏)，并想要创造一个关卡编辑器。我在将信息保存到.ser文件时遇到了麻烦，尽管我在其他类的其他地方这样做没有问题。错误是java.io.NotSerializableException: resources.Sample$Ball，但它给我的行号与这个类无关。我有一个叫做Sample的类，在这个类里面有一个叫做Ball的私有类，所以我明白了很多，但是它给我提供信息的事实是没有意义的。Sample类只在单个类中使用一次，并且它不是我得到错误的那个。我从来没有遇到过这个类或Ball子类的问题，因为它们非常隐蔽，很少使用。

错误给我的两个行号是: at LevelEditor.saveDialog(LevelEditor.java:309) at LevelEditor.actionPerformed(LevelEditor.java:256)

这些行号处的代码行如下: oos.writeObject(new CustomSave(platforms, stars, ball, levelSize));

这是问题实际发生的地方，而另一行号正是我调用上述代码所在函数的地方。CustomSave类接受的变量仍然与Sample或Ball类无关。因为CustomSave课程很小，我也会在这里提供。我还将为上面的行号提供上下文。

上下文到代码

try {
    File f = new File(filename);
    f.createNewFile();
    FileOutputStream fos = new FileOutputStream(f);
    ObjectOutputStream oos = new ObjectOutputStream(fos);
    oos.writeObject(new CustomSave(platforms, stars, ball, levelSize));
    oos.close();
} catch (Exception e1) {
    e1.printStackTrace();
}

<<p> CustomSave类/strong>

package resources;
import java.awt.Dimension;
import java.io.*;
import java.util.ArrayList;
import resources.BouncyBall;
public class CustomSave implements Serializable {
    private ArrayList<DragablePlatform> platforms;
    private ArrayList<StarPolygon> stars;
    private StaticBall ball;
    private Dimension levelSize;
    public CustomSave(ArrayList<DragablePlatform> platforms, ArrayList<StarPolygon> stars, StaticBall ball, Dimension levelSize){
        this.platforms = platforms; this.stars = stars; this.ball = ball; this.levelSize = levelSize;
    }
    public ArrayList<DragablePlatform> getPlatforms() {
        return platforms;
    }
    public ArrayList<StarPolygon> getStars() {
        return stars;
    }
    public BouncyBall getBall() {
        return ball;
    }
    public Dimension getLevelSize() {
        return levelSize;
    }
}

我不知道为什么我得到这个错误，因为它没有意义。为了尝试故障排除，我尝试在Sample类中的Ball类上实现Serializable，并在一定程度上解决了问题。错误不再将Sample$Ball列为问题，而是将另一个随机类列为问题，另一个类与我试图做的事情完全无关。

完整误差

java.io.NotSerializableException: resources.Sample$Ball
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeArray(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.access$300(Unknown Source)
at java.io.ObjectOutputStream$PutFieldImpl.writeFields(Unknown Source)
at java.io.ObjectOutputStream.writeFields(Unknown Source)
at java.awt.Container.writeObject(Unknown Source)
at sun.reflect.GeneratedMethodAccessor11.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
at java.io.ObjectOutputStream.writeObject0(Unknown Source)
at java.io.ObjectOutputStream.writeObject(Unknown Source)
at LevelEditor.saveDialog(LevelEditor.java:454)
at LevelEditor.actionPerformed(LevelEditor.java:298)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.AbstractButton.doClick(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Unknown Source)
at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

关卡编辑器第454行

oos.writeObject(new CustomSave(platforms, stars, ball, levelSize));

关卡编辑器第298行

saveDialog();(包含上面一行的函数)

所有的帮助都是非常感激的，如果你还需要什么就问我。

谢谢。

Answer 1

要正确序列化，你必须确保你要序列化的所有类都实现了Serializable接口，我曾经有过同样的问题，我试图一次保存一个对象，看看是什么对象引起了问题-冲洗。

try {        
    FileOutputStream fos = new FileOutputStream(new File(filename));
    ObjectOutputStream oos = new ObjectOutputStream(fos);
    oos.writeObject(platforms);
    oos.writeObject(stars);
    oos.writeObject(balls);
    oos.writeObject(levelSize);
    oos.flush();
    oos.close();
}catch (Exception e1) {
    e1.printStackTrace();
}

Answer 2

要使序列化/反序列化成功，必须满足以下两个条件:

1. 要序列化/反序列化的类必须实现java.io.Serializable接口。
2. 类中的所有字段必须是基本类型或者必须实现java.io.Serializable接口。

条件1(满足):sinceCustomSave implements Serializable

Condition 2 (?): Do StaticBall, DragablePlatform and StarPolygon实现Serializable?

private ArrayList<DragablePlatform> platforms; // ArrayList implements Serializable? Yes, DragablePlatform implements Serializable?
private ArrayList<StarPolygon> stars; // ArrayList implements Serializable? Yes, StartPolygon implements Serializable?
private StaticBall ball; // StaticBall implements Serializable?
private Dimension levelSize; // Dimension implements Serializable? Yes