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();
}
}
}
Related
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;
}
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();
}
}
}
}
I have a project where I am required to read and write a vector of bank account objects and I am struggling with this concept. I was able to figure it out when the accounts were not stored in a vector but now that I am dealing with vectors I am confused. If anyone can look at my code I would greatly appreciate it! Thanks in advance for your time!
This is my best attempt. Even though I know it's wrong, I just wanted to give you an idea of what I am trying to do.
public static void readTrans()
{
textArea.setText("");
chooseFile(1);
try
{
FileInputStream fis = new FileInputStream(filename);
ObjectInputStream in = new ObjectInputStream(fis);
for (int index=0; index != fileIndex; index++)
{
account = (CheckingAccount)in.readObject();
acctStore.add(index, account);
System.out.println("reading account " + acctStore.elementAt(index));
}
saveStatus = true;
in.close();
}
catch(ClassNotFoundException e)
{
System.out.println(e);
}
catch (IOException e)
{
System.out.println(e);
}
}
public static void writeTrans()
{
textArea.setText("");
chooseFile(2);
try
{
FileOutputStream fos = new FileOutputStream(filename);
ObjectOutputStream out = new ObjectOutputStream(fos);
for (int index=0; index != acctStore.size(); index++)
{
out.writeObject(acctStore.elementAt(index));
System.out.println("Writing account for " + acctStore.elementAt(index).getName() +" with initial balance: " + acctStore.elementAt(index).getBalance());
fileIndex++;
}
saveStatus = true;
out.close();
}
catch(IOException e)
{
System.out.println(e);
}
}
UPDATE:
Ok I think I figured it out however I am getting a warning since I casted the vector onto the CheckingAccount. Is this practice okay? The program is working as I expected so I am assuming so. Thanks again for your time!
Here's updated code:
public static void readTrans()
{
textArea.setText("");
chooseFile(1);
try
{
FileInputStream fis = new FileInputStream(filename);
ObjectInputStream in = new ObjectInputStream(fis);
acctStore = (Vector<CheckingAccount>)in.readObject();
saveStatus = true;
in.close();
}
catch(ClassNotFoundException e)
{
System.out.println(e);
}
catch (IOException e)
{
System.out.println(e);
}
}
public static void writeTrans()
{
textArea.setText("");
chooseFile(2);
try
{
FileOutputStream fos = new FileOutputStream(filename);
ObjectOutputStream out = new ObjectOutputStream(fos);
out.writeObject(acctStore);
saveStatus = true;
out.close();
}
catch(IOException e)
{
System.out.println(e);
}
}
I'm having problems with appending a generic object within an existing file. This method is supposed to append the object to the existing file if the parameters are "true" and overwrites the entire file if "false". The "false" statement works perfectly fine, it overwrites the entire file but I can't seem to get the append one to work. It seems to do nothing at first glance but when I placed a simple System.out.println("test"); in the while (true) loop, it runs forever. How can I fix this?
public <T> void writeOneObject(T type, boolean append) throws NotSerializableException{
if (append == true){
//TODO
if (file.exists ()){
ObjectOutputStream ois = null;
try{
ois = new ObjectOutputStream (new FileOutputStream (file, true));
while (true){
ois.writeObject(type);
}
}catch (StreamCorruptedException e){
}catch (EOFException e){
}catch (Exception e){
e.printStackTrace ();
}finally{
try{
if (ois != null) ois.close();
}catch (StreamCorruptedException e){
}catch (IOException e){
e.printStackTrace ();
}
}
}
}
else { //overwrites the entire file
try {
FileOutputStream fos = new FileOutputStream(file);
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(type);
oos.flush();
oos.close();
} catch (FileNotFoundException ex) {
ex.printStackTrace();
} catch (StreamCorruptedException e) {
System.out.println("error");
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
I also have this inside the class:
class NoHeaderObjectOutputStream extends ObjectOutputStream {
public NoHeaderObjectOutputStream(OutputStream os) throws IOException {
super(os);
}
protected void writeStreamHeader() {}
}
I have a big problem , I write in a txt file same objects Accounts when i click to see all objects i have write in txt is show me the last one only and how i show up the account in JOptionPane , the second is how i can make the account to take nuber one ,two , three...... every account i write to take a number plus one from the precedent account .
I believ to explain apparent
if( str.equals("Receipt") )
{
ObjectInputStream in = null;
Account acc = null;
try
{
in = new ObjectInputStream(new FileInputStream("Accounts.txt"));
while( (acc = (Account) in.readObject()) !=null)
{
if (acc instanceof Account)
((Account)acc).print();
//acc.print();
}
}
catch(EOFException ex)
{
System.out.println("End of file reached.");
}
catch(ClassNotFoundException ex)
{
System.out.println("Error casting");
ex.printStackTrace();
}
catch(FileNotFoundException ex)
{
System.out.println("Error specified file does not exist");
ex.printStackTrace();
}
catch(IOException ex)
{
System.out.println("Error with I/O processes");
ex.printStackTrace();
}
finally
{
try
{
in.close();
}
catch(IOException ex)
{
System.out.println("Another IOException during the closing");
ex.printStackTrace();
}
}
}
code to write object in file
Account ac=new Account(posoOfil,poso,ariLoga,aitiol,diafor);
ac.print();
try{
OutputStream file = new FileOutputStream("Accounts.txt");
OutputStream buffer = new BufferedOutputStream( file );
ObjectOutput output = new ObjectOutputStream( buffer );
try{
output.writeObject(ac);
output.flush();
System.out.println("Object written to file");
}
finally{
output.close();
}
}
catch
(FileNotFoundException ex) {System.out.println("Error with specified file") ;
ex.printStackTrace();}
catch(IOException ex){
System.out.println("Cannot perform output.");
}
}
And the class Account
public class Account implements Serializable {
private int arithmKat;
// private Date date ;
private int posoOfil;
private int posoKat;
private String ariLoga ;
private String aitiol;
private boolean diafor=false;
public Account(int posoOfil, int posoKat,String ariLoga,String aitiol,boolean diafor){
arithmKat++;
this.posoOfil=posoOfil;
this.posoKat=posoKat;
this.ariLoga=ariLoga;
this.aitiol=aitiol;
this.diafor=diafor;
}
void print(){
System.out.println(arithmKat+" "+posoOfil+" "+posoKat+" "+diafor);}
}
You only write one account to the file. There is no loop at all in the code writing the account. Code that would write several accounts would look like this:
private void writeAccounts(List<Account> accounts) throws IOException {
OutputStream file = new FileOutputStream("Accounts.txt");
OutputStream buffer = new BufferedOutputStream(file);
ObjectOutput output = new ObjectOutputStream(buffer);
try {
for (Account account : accounts) {
output.writeObject(account);
}
output.close();
}
finally {
output.close();
}
}