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ObjectOutputStream Resulting in EOF Error

I'm trying to implement object serialization in java. I'm not sure why my code is currently leading to an EOFException, as my code is writing to the file it's supposed to:
Currently, my code is:
import java.io.*;
public class main {
public static void main(String[] args) {
product p1 = new product("product", 0, "this is a product.");
ObjectOutputStream out = null;
try {
out = new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream("info.dat")));
out.writeObject(p1);
out.writeObject(p1);
System.out.println("Wrote to file");
} catch (FileNotFoundException e) {
System.out.println("");
} catch (IOException e) {
System.out.println("");
}
ObjectInputStream in = null;
try {
in = new ObjectInputStream(
new BufferedInputStream(
new FileInputStream("info.dat")));
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
while product class is extremely simple, being only:
import java.io.Serializable;
public class product implements Serializable {
String name;
double cost;
String description;
public product(String a,double b,String c) {
name = a;
cost = b;
description = c;
}
}
Currently, the output is
Meaning that my code did run and did write to file. I also added an extra write object just in case, so I really don't understand how an EOF error is occurring. Can somebody please explain why?

Reading objects from assets

something is really messed up. I've got a ".ser" document in the assets folder, which stores an ArrayList of Objetcs. In an android application, I want to read this objects. There are a lot of posts related to this issue, however none of them could solve my problem. The strange part is, when I am using similar code in non - android context / "normal" java, it works properly. Here, the last line throws a NullPointerException - What is going wrong?
public void getData() {
ArrayList<MyClass> output= null;
InputStream is = null;
ObjectInputStream ois = null;
try{
is = this.getAssets().open("data.ser");
ois = new ObjectInputStream(is);
output = (ArrayList<MyClass>)ois.readObject();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} finally {
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
ois.close();
} catch (IOException e) {
e.printStackTrace();
}
}
Log.d("TAG", output.get(0).getId());
}

I would create a class and place the array within a single object:
public class ListObjects implements Serializable {
List<MyClass> listMyClass = new ArrayList<>();
public ListObjects(){
}
public List<MyClass> getListMyClass() {
return listMyClass;
}
public void setListMyClass(List<MyClass> listMyClass) {
this.listMyClass = listMyClass;
}
}
I had a similar problem. And it was because the name of the package in the java app was not called the same as the package name in android. And therefore I did not recognize them as equal objects. This is how I do it:
public static Object fromData(byte[] data) {
ObjectInputStream ois = null;
Object object = null;
try {
ois = new ObjectInputStream(
new ByteArrayInputStream(data));
object = ois.readObject();
} catch (Exception ex) {
Logger.getLogger(ModeloApp.class.getName()).log(Level.SEVERE, null, ex);
} finally {
try {
ois.close();
} catch (Exception ex) {
Logger.getLogger(ModeloApp.class.getName()).log(Level.SEVERE, null, ex);
}
}
return object;
}

How do I write multiple objects to the serializable file and read them when the program is used again?

I want to maintain database of users of a Bank for my project. I am able to save the number of users in one serializable file. But when I try to save the user to database it adds only the latest one to database.
Below is the sneak peak of code which writes the objects:
if(e.getSource()==submit) {
if(uFName != null && uLName != null && uInitialDeposit !=0) {
if(uAccountType=="Savings") {
Random randomGenerator = new Random();
//Gets the number of users from file if file exists
File f = new File(fileNameAdmin);
if(f.exists() && !f.isDirectory()) {
admin=db.readFromAdminDatabase();
}
u[admin.numberOfUsers]= new User();
u[admin.numberOfUsers].fName=uFName;
u[admin.numberOfUsers].lName=uLName;
u[admin.numberOfUsers].initalDeposit=uInitialDeposit;
u[admin.numberOfUsers].interestRate=uInterestRate;
u[admin.numberOfUsers].accountType="Saving";
u[admin.numberOfUsers].accountNumber=690000+admin.numberOfSavingsAccount;
//Generates a 4 digit random number which will be used as ATM pin
u[admin.numberOfUsers].atmPin=randomGenerator.nextInt(9999-1000)+1000;
//A savings account will be created
sa[admin.numberOfSavingsAccount]=new SavingsAccount(u[admin.numberOfUsers].accountNumber,u[admin.numberOfUsers].fName,u[admin.numberOfUsers].lName,
u[admin.numberOfUsers].initalDeposit,
u[admin.numberOfUsers].interestRate);
u[admin.numberOfUsers].sa=sa[admin.numberOfSavingsAccount];
System.out.println(u[admin.numberOfUsers].sa.balance);
JOptionPane.showMessageDialog(submit,"Congratulations! You are now a member of Symbiosis Bank."
+ "\nYour account number is "+u[admin.numberOfUsers].accountNumber
+" and your ATM Pin is "+u[admin.numberOfUsers].atmPin,"Account Created",JOptionPane.INFORMATION_MESSAGE);
try {
//for(int j = 0; j<admin.numberOfUsers; j++)
db.addUserToDatabase(u[admin.numberOfUsers]);
admin.numberOfSavingsAccount++;
admin.numberOfUsers++;
db.updateAdminDatabase(admin);
dispose();
setVisible(false);
//Welcome welcome = new Welcome();
//welcome.setVisible(true);
InitialInput back = new InitialInput();
back.setVisible(true);
} catch (Exception e1) {
e1.printStackTrace();
}
}
}
The database class which has functions to write to database:
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
public class Database implements Serializable {
String fileName = System.getProperty("user.home")+"/db.ser";
String fileNameAdmin = System.getProperty("user.home")+"/admindb.ser";
public void addUserToDatabase(User u){
FileOutputStream fos;
try {
fos = new FileOutputStream(fileName);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(u);
oos.close();
}
catch(Exception e) {
e.printStackTrace();
}
}
#SuppressWarnings("finally")
public User readFromUserDatabase() {
FileInputStream fis;
User temp = null;
try {
fis = new FileInputStream(fileName);
ObjectInputStream ois = new ObjectInputStream(fis);
temp = (User)ois.readObject();
//System.out.println(temp.fName);
ois.close();
}
catch(Exception e) {
e.printStackTrace();
}
finally {
return temp;
}
}
public void updateAdminDatabase(Administrator admin) {
FileOutputStream fos;
try {
fos = new FileOutputStream(fileNameAdmin);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(admin);
oos.close();
}
catch(Exception e) {
e.printStackTrace();
}
}
#SuppressWarnings("finally")
public Administrator readFromAdminDatabase() {
FileInputStream fis;
Administrator temp = null;
try {
fis = new FileInputStream(fileNameAdmin);
ObjectInputStream ois = new ObjectInputStream(fis);
temp = (Administrator)ois.readObject();
//System.out.println(temp.fName);
ois.close();
}
catch(Exception e) {
e.printStackTrace();
}
finally {
return temp;
}
}
}
The code which is trying to read the database:
public void actionPerformed(ActionEvent e) {
if(e.getSource()==deposit) {
//Ask the amount to deposit
int userAmountToDeposit;
try {
for(int i = 0; i<=admin.numberOfUsers; i++) {
u[i] = db.readFromUserDatabase();
System.out.println(u[i].accountNumber);
}
for(int j =0; j<=admin.numberOfUsers; j++) {
if(u[j].accountNumber==userAccountNumber) {
if(u[j].atmPin==userPin) {
u[j].accountBalance=u[j].sa.balance;
u[j].sa.deposit(10);
u[j].accountBalance=u[j].sa.balance;
System.out.println(u[j].accountBalance);
}
}
}
}

Inorder to write and read multiple objects please try as below
Writing multiple object into List
WriteObject wo=new WriteObject(20, "Mohan");
WriteObject wo1=new WriteObject(21, "Mohanraj");
ArrayList<WriteObject> woi=new ArrayList<>();
try {
FileOutputStream fop=new FileOutputStream("c://object.ser");
ObjectOutputStream oos=new ObjectOutputStream(fop);
woi.add(wo);
woi.add(wo1);
oos.writeObject(woi);
} catch NotFoundException e) {
}
Reading all objects from file
try {
FileInputStream fis=new FileInputStream("C://object.ser");
ObjectInputStream ois=new ObjectInputStream(fis);
WriteObject wo=null;
WriteObject[] woj=new WriteObject[5];
ArrayList<WriteObject> woi=new ArrayList<>();
woi=(ArrayList<WriteObject>)ois.readObject();
for(int i=0;i<woi.size();i++){
woi.get(i).getvalues();
}
Here getvalues() is method present in Writeobject class. Follow the same mechanism for your code snippet

If you want to fix it rapidly, you can create a list and store first and foremost your objects in the list (may be ArrayList or List), and then you'll save this list on your file. That is the nice method. Make sure that your objects are serializable.
below, listeVoitures is a stactic variable that will contain all
object that i'm going to retrive from file.
public static void saveVehiculeInFile(ArrayList vehiculeList) {
ObjectOutputStream ous = null;
//ArrayList<Vehicule> listVehiculeToSave = new ArrayList<>();
try {
ous = new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream(new File("garage.txt"))));
try {
ous.writeObject(vehiculeList);
System.out.println("\t=====> Les vehicules *** ont été ajouter dans le garage.");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (ous != null) {
try {
ous.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
This method below is for retrive data from file
public static void readVehiculeFromFile() {
ObjectInputStream ins = null;
ArrayList<Vehicule> v = null;
try {
ins = new ObjectInputStream(new BufferedInputStream(new FileInputStream(new File("PoweredGarage.txt"))));
try {
v = (ArrayList<Vehicule>)ins.readObject();
} catch (ClassNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
for (Vehicule vehicule : v) {
listeVoitures.add(vehicule);
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally {
if (ins != null) {
try {
ins.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}

Can't create ObjectInputStream

Why can't I create an ObjectInputStream object? Every time I try to create one I get EOFException and I can't figure why. Can someone help me?
Below is the code with which I have the problem and the stack trace obtained from the execution. The file is empty.
public void loadFromFileStudent() throws IOException, ClassNotFoundException {
try{
InputStream inputStream = new FileInputStream("student.txt");
System.out.println(inputStream.toString());
ObjectInputStream objectInputStream;
objectInputStream = new ObjectInputStream(inputStream);
System.out.println(objectInputStream.toString());
this.repo=(Dictionary<Integer, Student>) objectInputStream.readObject();
objectInputStream.close();
inputStream.close();
}catch (EOFException e){
e.printStackTrace();;
//System.out.println(e.getMessage());
}
}
.
java.io.FileInputStream#65ddcac5
java.io.EOFException
at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2324)
at java.io.ObjectInputStream$BlockDataInputStream.readShort(ObjectInputStream.java:2793)
at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:799)
at java.io.ObjectInputStream.<init>(ObjectInputStream.java:299)
at repository.Repository.loadFromFileStudent(Repository.java:94)
at repository.Repository.<init>(Repository.java:112)
at utils.DataStructure.createRepository(DataStructure.java:16)
at controller.Controller.<init>(Controller.java:9)
at utils.DataStructure.createController(DataStructure.java:20)
at application.RunMenu.<init>(RunMenu.java:15)
at application.App.main(App.java:5)

EOFException is thrown when end-of-file is reached. That is, you have read the whole file. Therefore you should not close your streams within the try statement, but use try-with-resources to automatically close them.
Try something simple like this:
public void loadFromFileStudent() throws IOException, ClassNotFoundException {
try (InputStream inputStream = new FileInputStream("student.txt");
ObjectInputStream objectInputStream = new ObjectInputStream(inputStream)) {
this.repo = (Dictionary<Integer, Student>) objectInputStream.readObject();
} catch (FileNotFoundException e) {
System.out.println ("File not found");
} catch (IOException e) {
System.out.println ("Error while reading");
} catch (ClassNotFoundException e) {
System.out.println ("No class");
} catch (ClassCastException e) {
System.out.println ("Could not cast to class");
}
}
Writing is equally simple:
public void writeObject ( Object o ) {
try (FileOutputStream fos = new FileOutputStream ( this.filename );
ObjectOutputStream oos = new ObjectOutputStream(fos)) {
oos.writeObject(o);
oos.flush();
} catch (NotSerializableException e) {
System.out.println ("Object wont be serialized");
e.printStackTrace();
} catch (IOException e) {
System.out.println ("Error while writing to file");
e.printStackTrace();
}
}

From my understanding of the question I assume OP is doing some thing like below, and which should works. May be OP would have missed something during writing/reading. Hope this helps to figure out.
public class Test2 {
public static void main(String[] args) {
Test2 t = new Test2();
t.create();
t.read();
}
public void create(){
try{
ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream("D:\\test\\ab.txt"));
Student st = new Student("chevs");
Dictionary<Integer, Student> dict = new Hashtable<Integer, Student>();
dict.put(1, st);
os.writeObject(dict);
}catch(Exception e){
e.printStackTrace();
}
}
public void read()
{
try{
InputStream inputStream = new FileInputStream("D:\\test\\a.txt");
System.out.println(inputStream.toString());
ObjectInputStream objectInputStream;
objectInputStream = new ObjectInputStream(inputStream);
System.out.println(objectInputStream.toString());
private Dictionary<Integer, Student> repo=(Dictionary<Integer, Student>) objectInputStream.readObject();
System.out.println(repo.get(1));
objectInputStream.close();
inputStream.close();
}catch (Exception e){
e.printStackTrace();;
}
}
public class Student implements Serializable{
public String name=null;
public Student(String name){
this.name=name;
}
public String toString() {
return name.toString();
}
}
}

Can't serialize an ArrayList

This is a followup to Serializing a vector
I'm trying to implement loading and saving for a game I'm working on.
I want to save a Maze which contains, among other attributes, an ArrayList of Entity.
Entity is a super class for Dragon, Hero and Item. All three of these types can be contained at once in the vector.
Using the "automatic" serialization mechanism (adding implements Serializable to Maze) saves all attributes but the ArrayList.
Why does this happen?
My code is below, for completeness' sake.
package logic;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
public final class LoadAndSave {
public static final transient boolean available = false;
public static final boolean serialize(Object obj) {
// Write to disk with FileOutputStream
FileOutputStream saveFile;
try {
saveFile = new FileOutputStream("game.sav");
} catch (FileNotFoundException e) {
return false;
}
// Write object with ObjectOutputStream
ObjectOutputStream objOut;
try {
objOut = new ObjectOutputStream(saveFile);
} catch (IOException e) {
//
return false;
}
// Write object out to disk
try {
objOut.writeObject(obj);
} catch (IOException e) {
return false;
}
return true;
}
public static final Object load() {
FileInputStream fileIn;
try {
fileIn = new FileInputStream("game.sav");
} catch (FileNotFoundException e1) {
return null;
}
// Read object using ObjectInputStream
ObjectInputStream objIn;
try {
objIn = new ObjectInputStream(fileIn);
} catch (IOException e) {
return null;
}
// Read an object
Object obj;
try {
obj = objIn.readObject();
} catch (IOException e) {
return null;
} catch (ClassNotFoundException e) {
return null;
}
return obj;
}
}

Is Entity serializable too? (you mentioned that just Maze is serializable).
And be sure that the list is not defined as transient or static, otherwise it will be skipped by the serialization mechanism.

I checked Your code with the following assumptions:
class Entity implements Serializable {}
and:
private char[][] mazeWalls = new char[0][0];
private Vector<Entity> entities = new Vector<Entity>();
...and it works perfectly, serializing and deserializing empty Entity objects...

You need to make sure that you close your streams. Your code for load() can be simplified to look something like this:
ObjectInputStream objIn = null;
try {
objIn = new ObjectInputStream(new FileInputStream("game.sav"));
return objIn.readObject();
} catch (Exception exception) {
// Deal with errors
return null;
} finally {
if (objIn != null) {
try {
objIn.close();
} catch (Exception exception) {}
}
}
serialise() can be altered in a similar way.