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Looping through a ObjectInputStream in one method and print entire file in the main method, but having problems with EOF not working or erroring

So I have a working ObjectOutputStream in a method that I start by calling the method in main. I need to then read the file it created and print out all 5 objects in it. Right now I'm only printing out the first object.
public static AccountSerializable serializReadObject() throws ClassNotFoundException, IOException {
AccountSerializable read = null;
try { // Create an input stream for file accounts.ser
ObjectInputStream input = new ObjectInputStream(new FileInputStream("accounts.ser"));
read = (AccountSerializable) input.readObject();
input.close();
} catch (IOException i) {
throw i;
}catch(ClassNotFoundException c){
throw c;
}
return read;
}
public static void main(String[] args) {
try {
System.out.println(serializReadObject());
} catch (ClassNotFoundException | IOException e) {
System.out.println("Class not found");
e.printStackTrace();
}
}
I've tried to throw
boolean eof = false;
while(!eof){
try{
//read data
}catch(EOFException e){
eof = true;
}
}
in serializReadObject To loop it and I've also tried to instead catch it in main but I keep getting an error stating "Unreachable catch block for EOFException it is already handled by the catch block"
I then tried to take away the IOException and just put EOFEception but alas it keeps forcing me to surround my read with IOException. Is there another way to loop this with EOF?

You're only getting the first object because your opening and closing the stream on each call. There are many ways to achieve what you want. One way is to use a List<AccountSerializable>:
public static List<AccountSerializable> serializeReadObjects() throws IOException, ClassNotFoundException {
// create an input stream for file accounts.ser
// this line will throw an IOException if something goes wrong
// we don't need to catch it in this method though
ObjectInputStream input = new ObjectInputStream(new FileInputStream("accounts.ser"));
// create list to hold read in accounts
List<AccountSerializable> accounts = new ArrayList<>();
// keep reading until EOFException is thrown
boolean keepReading = true;
while(keepReading) {
try {
// read in serialized account
AccountSerializable read = (AccountSerializable) input.readObject();
// add read in serialized account to the list
accounts.add(read);
} catch(EOFException eofe) {
// we are at the end of file, so stop reading
keepReading = false;
input.close();
} catch(IOException ioe) {
// input stream error other than EOF, not sure what to do
input.close();
throw ioe;
} catch(ClassNotFoundException cnfe) {
// not sure what to do in this case, so close input
input.close();
throw cnfe;
}
}
return accounts;
}
public static void main(String[] args) {
List<AccountSerializable> accounts = null;
try {
// get list of read in accounts
accounts = serializeReadObjects();
} catch (ClassNotFoundException | IOException e) {
e.printStackTrace();
}
// iterate over list of read in accounts and output them to stdout
for(AccountSerializable account : accounts) {
System.out.println(account);
}
}

Workaround java.io.EOFException cause by ObjectInputStream [duplicate]

This question already has answers here:
java.io.FileNotFoundException when creating FileInputStream
(2 answers)
Closed 6 years ago.
For my application I want to use a Map to act as a database. To save and load a map, I am writing/reading it to/from database.ser using this 2 methods:
private synchronized void saveDB() {
try {
fileOut = new FileOutputStream(db);
out = new ObjectOutputStream(fileOut);
out.writeObject(accounts);
fileOut.close();
out.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
#SuppressWarnings("unchecked")
private void loadDB() {
try {
fileIn = new FileInputStream(db);
in = new ObjectInputStream(fileIn); // that is where error is produced if fileIn is empty
accounts = (Map<String, Client>) in.readObject();
in.close();
fileIn.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
I want to load into Map when application starts, so I invoke method in constructor like this:
protected DriveatorImpl() {
accounts = new ConcurrentHashMap<String, Client>();
db = new File("C:/Users/eduar/git/Multy-Threaded-Bank-System/Bank-Services/database.ser");
// also, any suggestions how can I make path to a file more flexible in case I want to run Server side of an app on different machine?
if (!db.exists()) {
try {
db.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
loadDB(); // loads database when server start
}
I am aware of what causing an error, but I don't know what should I change in my design to avoid ObjectInputStream constructor receiving empty stream!
Any suggestions on what I can do differently?
Edit: I want to note that in fresh application run database.ser is empty since there was no entries made into Map yet.
Thank You!

First why the EOFExcpetion occur?
There are no contents in file or file is empty and you tried to read file.
You can avoid the EOFException for an empty file by checking file content length if it is less than or equal to zero means file is empty. another way to check if file is empty
Some code change and it worked for me.
#SuppressWarnings("unchecked")
private void loadDB() {
try {
if (db.length() <= 0) {
// if statement evaluates to true even if file doesn't exists
saveDB(); // save to a file an empty map
// if file doesn't exist, it creates a new one
// call loadDB inside constructor
}
FileInputStream fileIn = new FileInputStream(db);
ObjectInputStream in = new ObjectInputStream(fileIn); // that is where error is produced if fileIn is empty
in.readObject();
in.close();
fileIn.close();
System.out.println(accounts);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

Get rid of the file.exists()/file.createNewFile() crap. All it is doing for you is masking the original FileNotFoundException problem, and turning into a thoroughly predictable EOFException because of trying to construct an ObjectInputStream around an empty stream. Handle the original problem. Don't just move it, or turn it into something else.

Using FileInputStream compile error says variable is uninitialized

Can somebody tell me what am I doing wrong in the below java code ? It doesn't compile and gives me compilation error.
import java.io.*;
public class ShowFile {
public static void main(String[] args) {
int i;
FileInputStream Fin;
try {
Fin = new FileInputStream("C:\\Users\\cbr\\Desktop\\test.txt");
} catch (FileNotFoundException exp) {
System.out.println("exception caught" + exp);
}
try {
do {
i = Fin.read();
System.out.print((char) i);
} while (i != -1);
} catch (IOException exp) {
System.out.println("Exception caught" + exp);
}
finally {
try {
Fin.close();
} catch (IOException exp) {
System.out.println("Exception caught" + exp);
}
}
}
}
while the below code compiles. You can see both initialization are within try block.
import java.io.*;
class ShowFile2 {
public static void main(String args[]) {
int i;
FileInputStream fin;
// First make sure that a file has been specified.
try {
fin = new FileInputStream("C:\\Users\\cbr\\Desktop\\test.txt");
} catch (FileNotFoundException exc) {
System.out.println("File Not Found");
return;
}
try {
// read bytes until EOF is encountered
do {
i = fin.read();
if (i != -1) {
System.out.print((char) i);
}
} while (i != -1);
} catch (IOException exc) {
System.out.println("Error reading file.");
}
try {
fin.close();
} catch (IOException exc) {
System.out.println("Error closing file.");
}
}
}

The problem is, that if new FileInputStream("C:\\Users\\cbr\\Desktop\\test.txt"); throws an exception, your variable will not be initialized in the second part of your method. This is not allowed. Object members will be initialized to null when the object is created, but this is not the case for local variables: they must be initialized explicitly.
A quick fix (but read on for a better fix) would be to initialize your variable (to null) when you are defining it:
FileInputStream fin = null;
This will solve your compilation error, however, you will get NullPointerExceptions when an exception is thrown in the first catch block.
A better solution is to put your error handling logic in the same place: if creating the FileInputStream fails, you don't want to read bytes from it anyway. So you can use a single try-catch block:
try {
fin = new FileInputStream("C:\\Users\\cbr\\Desktop\\test.txt");
// Read bytes from fin.
...
} catch (IOException e) {
// handle exception
...
}
Final advice: to make sure that your input stream is closed in all circumstances, you can use a try-with-resources block:
try (fin = new FileInputStream("C:\\Users\\cbr\\Desktop\\test.txt")) {
// Read bytes from fin.
...
} catch (IOException e) {
// handle exception
...
}

It does compile because the ShowFile2 class contains return in the catch block: this will ensure that the variable fin will be always initialized.
In the first class you caught the exception and you continue the execution of your program.

EOFException Runtime Error while dealing with SealedObject

I am currently experimenting with the encryption and decryption of objects but I am stumbling upon an EOFException every time my read method is declared. I feel like there is a lot of redundancy within my code trying to deal with all of the exceptions so it would be great if you could tell which catch/throw phrases to remove and how I can resolve this problem. Thanks.
java.io.EOFException points to the line in my code with (** **). All the other lines are NetBeans generated code.
public static void readFromBinary() throws IllegalBlockSizeException, EOFException
{
try {
BufferedReader br3 = new BufferedReader(new FileReader(noteFileName));
if (br3.readLine() != null) {
FileInputStream fINoteStream = new FileInputStream(noteFileName);
ObjectInputStream oINoteStream = new ObjectInputStream(fINoteStream);
while(true){
try{
**SealedObject sObj = (SealedObject)oINoteStream.readObject();**
Note note = (Note) sObj.getObject(new NullCipher());
noteList.add(note);
}
catch(EOFException e){
e.printStackTrace();
break;
}
catch (IllegalBlockSizeException e){
e.printStackTrace();
break;
}
catch (BadPaddingException e){
e.printStackTrace();
break;
}
catch (ClassNotFoundException e){
e.printStackTrace();
break;
}
}
oINoteStream.close();
}
}
catch (FileNotFoundException e){
e.printStackTrace();
}
catch (IOException e){
e.printStackTrace();
}
}
}
Method Call in another class:
try{
DataStorage.readFromBinary();
}
catch (IllegalBlockSizeException e)
{
e.printStackTrace();
}
catch (EOFException e)
{
e.printStackTrace();
}

EOFException just means you got to the end of the input. You need to close the inout and break out of the loop. You don't need to print the stack trace. It doesn't have anything to do with SealedObject specifically, just with how object streams work.
You need to decide whether you're catching this exception or throwing it. You shouldn't do both.

Learning handling exceptions, can't figure out this FileNotFoundException

I'm a beginner still, and currently learning about handling exceptions. The exercise in my book I'm trying to figure out tells me to add a Finally block to close out the file I opened, and I don't understand what I'm doing wrong. Keep in mind the file name and path are fake but here is what I have:
public static String readLineWithFinally()
{
System.out.println("Starting readLineWithFinally method.");
RandomAccessFile in = new RandomAccessFile("products.ran", "r");
try
{
String s = in.readLine();
return s;
}
catch (IOException e)
{
System.out.println(e.toString());
return null;
}
finally
{
try
{
in.close();
}
catch (Exception e)
{
System.out.println("Generic Error Message");
}
}
}

To add on to Taylor Hx's answer, you can take advantage of Java 7's try-with-resources construct to avoid having to use finally altogether in your case.
public static String readLineWithFinally() {
System.out.println("Starting readLineWithFinally method.");
try (RandomAccessFile in = new RandomAccessFile("products.ran", "r")) {
return in.readLine();
} catch (IOException e) {
System.out.println(e.toString());
return null;
}
}
You'll also want to be certain that your usage is consistent with what the API mandates for RandomAccessFile.

The code that you posted shouldn't compile, as RandomFile(String, String) can possibly throw FileNotFoundException. As such, we must include it in the try block.
System.out.println("Starting readLineWithFinally method.");
RandomAccessFile in = null;
try {
in = new RandomAccessFile("products.ran", "r");
String s = in.readLine();
return s;
} catch (IOException e) {
System.out.println(e.toString());
return null;
} finally {
try {
if(in != null) {
in.close();
}
} catch (Exception e) {
System.out.println("Generic Error Message");
}
}

Keep in mind the file name and path are fake but here is what I have:
That is why you will have a FileNotFoundException while creating RandomAccessFile("products.ran", "r") with read access mode "r".
From the documentation: RandomAccessFile(String name, String mode)
This constructor throws a FileNotFoundException if the mode is
"r" but the given string does not denote an existing regular file,
or if the mode begins with "rw" but the given string does not denote
an existing, writable regular file and a new regular file of that name
cannot be created, or if some other error occurs while opening or
creating the file