将ArrayList保存到文件

Question

I have a Arraylist, which i want to save in a file for use in the application another time, I've read several places that i can use this code to do this, but it doesn't work, it returns a error right after it prints out 3:

 private void savegame(){
    try {System.out.println("1");
        FileOutputStream preout = new FileOutputStream(new File("savedgame.ser"));
        System.out.println("2");
        ObjectOutputStream out = new ObjectOutputStream(preout);
        System.out.println("3");
        out.writeObject(kortene);
        System.out.println("4");
        out.close();
        System.out.println("5");
        preout.close();
        System.out.println("6");
        output = new FileWriter(new File("saved game settings.txt"));
        System.out.println("7");
        output.write(Indstillinger.BilledeMappe+"\n"+Indstillinger.AntalKort+
                "\n"+Indstillinger.AntalSpillere+"\n"+clicks+"\n"+Score);
        System.out.println("8");
        output.close();
        System.out.println("game save success");
    }catch (Exception e) {
        System.out.println("game save failed");
    }

and "kortene" is a ArrayList created like this:

public static ArrayList<Kort> kortene = new ArrayList<Kort>();

and Kort is a class i made, but that isn't relevant for this problem i assume..

the error i get is: java.io.NotSerializableException: java.awt.image.BufferedImage

but i dont have a BufferedImage, i just have a normal image in each of the classes...

Answer 1

Believe the compiler: if it says it's using BufferedImage to hold your images in memory, then it's true. The javadocs say it's not Serializable :

http://download.oracle.com/javase/1.5.0/docs/api/java/awt/image/BufferedImage.html

You can mark your images as transient and re-initialize them from the file system when you de-serialize later. Give that a go.

Answer 2

I assume the field declared in your class is of type Image but it was assigned an object BufferedImage during runtime. Thus it cannot write this to the output file since BufferedImage is not serializable.