如何在Android中进行序列化和反序列化？

Question

my mainActivity has a ListView which should display my CustomList:

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;

public class CustomList implements Serializable {
    private static final long serialVersionUID = 1L;
    private ArrayList<Game> list = new ArrayList<Game>();
    public void add(Game toAdd){
        list.add(toAdd);
    }
    public Game get(int id){
        return list.get(id);
    }
    public ArrayList<Game> getList(){
        return list;
    }
    public void serialize(){
        try {
            FileOutputStream fo = new FileOutputStream("res\\data.dat");
            ObjectOutputStream ou = new ObjectOutputStream(fo);
            ou.writeObject(list);
            ou.close();
            fo.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public void deserialize(){
        try {
            FileInputStream fi = new FileInputStream("res\\data.dat");
            ObjectInputStream oi = new ObjectInputStream(fi);
            list = (ArrayList<Game>)oi.readObject();
            oi.close();
            fi.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

I get the following error trying to serialize or desirialize:

java.io.FileNotFoundException: res\data.dat: open failed: ENOENT (No such file or directory)

My question is how to proper point to my data.dat file. Thanks in advance

Answer 1

You can't write into the res directory (that's read-only), you have to write to somewhere else, eg to the cache directory (if it's only temporary; use context.getCacheDir() to get it's location) or to some permanent space (eg context.getFilesDir() ).

You can get the file location like this, what you can pass to the FileOutputStream's or the FileInputStream's constructor:

File file = new File(context.getFilesDir(), "data.dat");

You may also have to request permission to write to external storage if you choose so.

Read more about storing files in Android here: http://developer.android.com/training/basics/data-storage/files.html