Solved

How to save a file with records.

Posted on 2002-07-06
5
216 Views
Last Modified: 2010-03-31
I have defined a class in Java similar to a Delphi's record, now I need to save those "records" in a file on my hard disk. Someone here gave this code:
/***********************
//Write your array of Records:

MyRecordClass[] aRecs = new MyRecordClass[10];

for (int i = 0; i < 10; i++)
 aRecs[i] = new MyRecordClass();
}

ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("c:\\myfile.obj"));

oos.writeObject(aRecs);

oos.close();

/***********************

But when I tried to do it I got the following error.

Exception occurred during event dispatching:
java.security.AccessControlException: access denied (java.io.FilePermission e:\m
yfile.obj write)
        at java.security.AccessControlContext.checkPermission(AccessControlConte
xt.java:272)
        at java.security.AccessController.checkPermission(AccessController.java:
399)
        at java.lang.SecurityManager.checkPermission(SecurityManager.java:545)
        at java.lang.SecurityManager.checkWrite(SecurityManager.java:978)
        at java.io.FileOutputStream.<init>(FileOutputStream.java:96)
        at java.io.FileOutputStream.<init>(FileOutputStream.java:62)
        at Clientes.GrabaFile(Clientes.java:296)
        at Clientes.actionPerformed(Clientes.java:334)
        at java.awt.Button.processActionEvent(Button.java:329)
        at java.awt.Button.processEvent(Button.java:302)
        at java.awt.Component.dispatchEventImpl(Component.java:2593)
        at java.awt.Component.dispatchEvent(Component.java:2497)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:339)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchTh
read.java:131)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:98)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:85)
0
Comment
Question by:rvaldivia
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
5 Comments
 

Author Comment

by:rvaldivia
ID: 7134328
I opened the java.policy file and added this line:
grant {permission ava.io.FilePermission "e:\\*", "write";};

Now I'm getting this error:

java.io.NotSerializableException: Clientes$Usuario
        at java.io.ObjectOutputStream.outputObject(ObjectOutputStream.java:1148)

        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:366)
        at java.io.ObjectOutputStream.outputArray(ObjectOutputStream.java:1098)
        at java.io.ObjectOutputStream.checkSubstitutableSpecialClasses(ObjectOut
putStream.java:456)
        at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:361)
        at Clientes.GrabaFile(Clientes.java:299)
        at Clientes.actionPerformed(Clientes.java:336)
        at java.awt.Button.processActionEvent(Button.java:329)
        at java.awt.Button.processEvent(Button.java:302)
        at java.awt.Component.dispatchEventImpl(Component.java:2593)
        at java.awt.Component.dispatchEvent(Component.java:2497)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:339)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchTh
read.java:131)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThre
ad.java:98)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:85)

0
 
LVL 92

Expert Comment

by:objects
ID: 7134334
For objects to be written using ObjectOutputStream then the class needs to implement the Serializable interface.
From the exception it appears the inner class Clientes$Usuario does not implement Serializable.
0
 

Author Comment

by:rvaldivia
ID: 7134338
Thanx it worked, but when I try to retrieve it using

try{
  ObjectInputStream ois = new ObjectInputStream(new FileInputStream("e:\\myfile2.obj"));
  Clientes = (Clientes.Usuario[])ois.readObject();
  ois.close();
}
catch(IOException ioe){
  System.out.println("Some kind of File Error happened!!!");
  ioe.printStackTrace();
}

I'm getting this error when I compile it:
E:\Edatos\EDATOSPROY01\clientes\Clientes.java:314: unreported exception java.lang.ClassNotFoundException; must be caught or declared to be thrown
               Clientes = (Clientes.Usuario[])ois.readObject();

0
 
LVL 92

Expert Comment

by:objects
ID: 7134351
Are you trying to read the file written by the code above?
If so, then you should be doing:

MyRecordClass[] recs = (MyRecordClass[]) ois.readObject();
0
 
LVL 35

Accepted Solution

by:
girionis earned 300 total points
ID: 7134856
>E:\Edatos\EDATOSPROY01\clientes\Clientes.java:314:
>unreported exception java.lang.ClassNotFoundException;
>must be caught or declared to be thrown
>              Clientes = (Clientes.Usuario[])ois.readObject();

  You should catch a ClassNotFoundException. Either throw it with your ethod declaration where the Clients = ... codes is or either use a try catch block like:

try
{
    Client = (Client.Usuario[]) ois.readObject();
}
catch (ClassNotFoundException cnfe)
{
}

  Hope it helps.
0

Featured Post

Salesforce Has Never Been Easier

Improve and reinforce salesforce training & adoption using WalkMe's digital adoption platform. Start saving on costly employee training by creating fast intuitive Walk-Thrus for Salesforce. Claim your Free Account Now

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

INTRODUCTION Working with files is a moderately common task in Java.  For most projects hard coding the file names, using parameters in configuration files, or using command-line arguments is sufficient.   However, when your application has vi…
By the end of 1980s, object oriented programming using languages like C++, Simula69 and ObjectPascal gained momentum. It looked like programmers finally found the perfect language. C++ successfully combined the object oriented principles of Simula w…
Viewers learn about the third conditional statement “else if” and use it in an example program. Then additional information about conditional statements is provided, covering the topic thoroughly. Viewers learn about the third conditional statement …
This tutorial covers a step-by-step guide to install VisualVM launcher in eclipse.
Suggested Courses

624 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question