Reading an Object From a File : Object Serialization « File « Java Tutorial

1. Java Tutorial
2. File
3. Object Serialization

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class MainClass {
  public static void main(String[] args) throws Exception {
    Junk obj1 = new Junk("A");
    Junk obj2 = new Junk("B");
    Junk obj3 = new Junk("V");
    ObjectOutputStream objectOut = new ObjectOutputStream(new BufferedOutputStream(
        new FileOutputStream("C:/JunkObjects.bin")));

    objectOut.writeObject(obj1); // Write object
    objectOut.writeObject(obj2); // Write object
    objectOut.writeObject(obj3); // Write object
    objectOut.close(); // Close the output stream

    ObjectInputStream objectIn = null;
    int objectCount = 0;
    Junk object = null;

    objectIn = new ObjectInputStream(new BufferedInputStream(new FileInputStream(
        "C:/JunkObjects.bin")));

    // Read from the stream until we hit the end
    while (objectCount < 3) {
      object = (Junk) objectIn.readObject();
      objectCount++;
      System.out.println(object);
    }

    objectIn.close();

  }
}

class Junk implements Serializable {
  String str;

  public Junk(String s) {
    str = s;
  }

}