Serialization example, reading the data back into the object

[merik]

I'm trying to create a class which can store its data in a serialized format to disk, and then load the serialized data back into itself.

I have an incomplete code here:

package example;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class Test implements Serializable {

	private static int[] items = new int[10];
	private static int location = 0;

	public void addValue(int val) {
		items[location] = val;
		location = (location + 1) % 10;
	}

	public void printAll() {
		for (int i = 0; i < 10; i++) {
			if (items[i] != 0) {
				System.out.println(items[i]);
			}
		}
	}

	public void save() {
		try {
			FileOutputStream FOS = new FileOutputStream("data.ser");
			ObjectOutputStream OOS = new ObjectOutputStream(FOS);

			OOS.writeObject(this);

			OOS.close();
			FOS.close();
		} catch (FileNotFoundException f) {
			//
			f.printStackTrace();
		} catch (IOException i) {
			//
			i.printStackTrace();
		}
	}

	public void load() {
		try {
			FileInputStream FIS = new FileInputStream("data.ser");
			ObjectInputStream OIS = new ObjectInputStream(FIS);

			Object temp = OIS.readObject();

			OIS.close();
			FIS.close();
		} catch (FileNotFoundException f) {
			//
			f.printStackTrace();
		} catch (IOException i) {
			//
			i.printStackTrace();
		} catch (ClassNotFoundException e) {
			//
			e.printStackTrace();
		}
	}

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Test t = new Test();
		t.addValue(14);
		t.addValue(5);
		t.printAll();
		t.save();
		t.addValue(32);
		t.load();
		System.out.println("Loading the same data above");
		t.printAll();
	}
}

I don't know how to proceed from here. Bascially, I don't know how to use the data I've read from the serialized file into the temp object, to update the Test instance.

[eRaaaa]

first, remove the static in

	
private static int[] items = new int[10];
private static int location = 0;

but you could make the load method static and return the Test instance:

	public static Test load() throws IOException, ClassNotFoundException  { //or use try catch here...
			FileInputStream FIS = new FileInputStream("data.ser");
			ObjectInputStream OIS = new ObjectInputStream(FIS);
			Test temp = (Test) OIS.readObject();
			OIS.close();
			FIS.close();
			return temp;
	}

and call t = Test.load();

(btw: read the naming conventions :D )

[merik]

Thanks for your answer, but this way, I need to reassign T variable:

t = Test.load();

However, what I really want to do is to just call a method of "t" instance and it'll load itself. Is that possible?

[eRaaaa]

if i understand you correctly, then: no! :)

but indirectly, in your example, you could serialize only the integer array! in other cases, you could write a wrapper or something similar to that maybe ?!