Reading / Writing a VECTOR to diskfile...

> I print the file after reading, and only get partial info (the extended parts of the

> original 'Person' class called PersonalFriend or BusinessAssociate), and it doesn't

> cast it into the Vector at all..

I'm not sure I understand this. Perhaps you could post some (brief) code that

illustrates your problem - something that writes then reads a Vector.

The following - using the two code extracts you provided does what it should:import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.Serializable;

import java.util.ArrayList;

import java.util.List;

import java.util.Vector;

public class Person implements Serializable {

private String name;

public Person(String name) {

this.name = name;

}

public String toString() {

return "Person: " + name;

}

private static final String FILE_NAME = "data.dat";

/**

* @param args

*/

public static void main(String[] args) throws IOException, ClassNotFoundException {

Vector testData = new Vector();

testData.add(new Person("Arthur"));

testData.add(new Person("Bob"));

testData.add(new Person("Charlie"));

System.out.println(testData);

writeData(testData);

testData = readData();

System.out.println(testData);

}

private static void writeData(Vector personVector) throws IOException {

File diskFile = new File(FILE_NAME);

FileOutputStream fos = new FileOutputStream(diskFile);

ObjectOutputStream oos = new ObjectOutputStream(fos);

oos.writeObject(personVector);

oos.close();

}

private static Vector readData() throws IOException, ClassNotFoundException {

ObjectInputStream ois = new ObjectInputStream(new FileInputStream(FILE_NAME));

//personVector = new Vector();

Vector personVector = (Vector)ois.readObject();

ois.close();

return personVector;

}

}

The output is:[Person: Arthur, Person: Bob, Person: Charlie]

[Person: Arthur, Person: Bob, Person: Charlie]

pbrockway2a at 2007-7-10 2:42:50 >

> the Vector comes back EMPTY, so is therefore NOT being cast properly...

On the contrary, if the Vector comes back empty it is being cast properly: since

only vectors (and not objects generally) are capable of being empty.

The question is, therefore, why is it empty?

All sorts of possibilities suggest themselves: one or other of the catch blocks silently

cuttting the write or read process short before it has finished, one file being written

and another being read, the vector being tested for emptiness (or printed or

whatever) not being the same s the vector that was read, ... Who shall say? The

list of possible problems is endless.

That's why I suggested you post some code that illustrates the problem. Something

brief that compiles and runs and shows the problem you are having. The tricky bit

(and it is tricky) is coming up with something that is brief and self contained, yet

still shows the problem. Often the effort spent on constructing such an example is

rewarded with a solution suggesting itself as all the distractions are cleared away.

> I've tried implementing your code, but it STILL is not showing anything in the

> Vector...

My code gives the output that I said it gives. I only really posted it to show that what

you had posted was not really the problem. The problem lies somewhere else;

somewhere in the code you have not posted.

(By the way, you declare personVector inside the try block which is kind of

weird if you ever intend doing anything with it, even printing it. It suggests we are

still seeing a rather edited version of the code.)

pbrockway2a at 2007-7-10 2:42:50 >

Here is EXACTLY what I have written...

private static void downloadBook(Vector personVector) throws IOException{

String pathName = "A:\\"; //Set the DEFAULT path

final char delimiter = File.separatorChar;

System.out.print("\n \t [* System-dependent path seperator character is " + delimiter + " *] \n");

System.out.print("\n \t Please enter the FILENAME to be saved: -->>");

String inputFileName = MyInput.readString(); //Get the FILE NAME from the user

inputFileName = inputFileName.trim(); //Trim off any leading or trailing spaces

//Create the FILENAME using the DEFAULT and USER INPUT (if any was made)

if (inputFileName != "") {

pathName += inputFileName;

}

try {

File diskFile = new File(pathName);

FileOutputStream fos = new FileOutputStream(diskFile);

ObjectOutputStream oos = new ObjectOutputStream(fos);

oos.writeObject(personVector);

oos.close();

} //Ends TRY

catch (Exception e) {

e.printStackTrace();

} //Ends CATCH

} //Ends DOWNLOADBOOK method

private static void uploadBook() throws IOException, ClassNotFoundException {

Vector personVector = new Vector();

String pathName = "A:\\"; //Set the DEFAULT path

final char delimiter = File.separatorChar;

System.out.print("\n \t [* System-dependent path seperator character is " + delimiter + " *] \n");

System.out.print("\n \t Please enter the subdirectory or filename (or hit Enter for default): -->>");

String inputFileName = MyInput.readString(); //Get the FILE NAME from the user

inputFileName = inputFileName.trim(); //Trim off any leading or trailing spaces

//Create the FILENAME using the DEFAULT and USER INPUT (if any was made)

pathName += inputFileName;

final File diskFile = new File(pathName); //Create an instance of the FILE class using the user input

if (!diskFile.exists()) {

System.out.print("\n \t " + pathName + " does not exist... \n \t Please try again!");

}

else {

if (diskFile.isDirectory()) {

System.out.print("\n \t " + pathName + " is the current directory.");

String[] contents = diskFile.list();

if (contents == null) {

System.out.print("\n \t and it is EMPTY!");

}

else { //If the directory is there, and not empty, display files in columns

System.out.print("\n \t There are " + contents.length + " files present: \n ");

for (int counter = 0; counter < contents.length; counter++) {

System.out.print("\n \t " + contents[counter]);

if ((counter + 1) % 3 == 0)

System.out.println("");

} //Ends the FOR loop

System.out.println("");

} //Ends the CONTENTS NULL 'if' statement

} //... IS IT A DIRECTORY 'if' statement

else { //Not a DIRECTORY

if (diskFile.isFile()) {

try {

ObjectInputStream ois = new ObjectInputStream(new FileInputStream(diskFile));

personVector = (Vector)ois.readObject();

ois.close();

System.out.print(personVector);

} //Ends TRY

catch (Exception e) {

e.printStackTrace();

} //Ends CATCH

} //Ends ISDISKFILE 'if' statement

else { //Not a file - display error message

System.out.print("\n \t Sorry, file name entered is not a valid");

System.out.print("\n \t file in the directory " + pathName);

} //Ends the ISFILE 'if' statement

} //Ends the NOT DIRECTORY else

} //Ends the FILE EXISTS 'if' statement

} //Ends UPLOADBOOK method

If you see something, I would appreciate a holler back...

If you need me, I will be out in the back yard eating worms...

:-(

dewlovera at 2007-7-10 2:42:50 >