How To Use Serialization In Singleton
Nov 28, 2014What is serialization in Java ?how to use serialization in Singleton?
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What Is Serialization In Java
Apr 8, 2015what is seriazable.But I am not able to come that why it is used and when should I declare my class(Object) as serialzable and when not?
View Replies View RelatedDifferent Hashcode For Object Before And After Serialization
Mar 11, 2014I am studying Serialization from the SCJP 6 Kathy Sierra book. I came across this code snippet.
public class Cat implements Serializable {
public static void main(String[] args) {
Cat c = new Cat();
try {
FileOutputStream fs = new FileOutputStream("testSer.ser");
ObjectOutputStream os = new ObjectOutputStream(fs);
os.writeObject(c);
[code]....
The output is as follows.
files.Cat@4d43691d
files.Cat@7f39ebdb
1) Why are the two hashcodes different?
2) Serialization is supposed to make and identical copy of any object and all its instance variables. So, if the hashcodes are different, are these objects located in different locations in heap?
Java Swing App Serialization
Jan 19, 2014I am trying to save a state of a big GUI Swing app. I am trying to save the containers (ArrayLists and JPanels too ). But I am recieving an exceptions:
Java Code:
ilian.Quiz.MainApp$5
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1183)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1547)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1508)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1431)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1177)
at java.io.ObjectOutputStream.writeArray(ObjectOutputStream.java:1377)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1173)
at java.io.ObjectOutputStream.access$300(ObjectOutputStream.java:162)
[code]...
What is causing it? I guess anonymous classes like new Thread(new Runnable(...) will cause errors.
Difference Between Serialization Vs Externalization
Dec 4, 2013Difference between Serialization Vs Externalization
View Replies View RelatedRead And Rewrite On XML File - Serialization?
May 19, 2015I'm building GUI and whole app is going to read and rewirte on xml file..
First I make function for read and write and they are working, but now I decide to make one class where I'm going to have get and set.. This is my class wehre I need to read everything from xm class CurrentData {
private String USERNAME = "username";
private String PASSWORD = "password";
private String STATUS = "status";
public String getusername() {
return username;
[Code] ....
Now my idea is when I start app that everything from xml is going to read from xml and trough get is going to show on my interface, when I edit I'm going to save and with function create I'm going to make same xml file with different parameters... how to use serialization...
Java Serialization With Inheritance And Aggregation
Feb 20, 2015What is difference between Java Serialization with Inheritance (IS-A Relationship) and Java Serialization with Aggregation (HAS-A Relationship) ....
View Replies View RelatedGive A Complete Resource Of File I/O Serialization
Aug 15, 2014Can you tell me or give a complete resource of file I/O, serialization!
View Replies View RelatedWhat Is The Need For Singleton Class
Jun 12, 2013If i am correct, a singleton class is the one for which only one object is allowed to create right. so why can't i just use everything in that as static and access them using the class name ? what is the need to create a single object ?
View Replies View RelatedSingleton Pattern In Java
Apr 21, 2003I have heard about using patterns in core java.Is it possible?If yes, how?
View Replies View RelatedTo Obtain Explanation On Singleton Implementation
Jan 11, 2014I've found following code for Singleton Implementation from this forum, I am having a difficulty of understanding following,
1. When Singleton instance will be created, ( From which call ) ?
2. What feature of Static Inner class allow object to be singleton ?
3. How Inner Class implementation is thread safe ?
4. What will happen if variable "instance" mark as non-static, Will it still grantee singleton implementation ?
Java Code:
public class Singleton {
// Note private constructor
private Singleton() {}
private static class SingletonInner {
private final static Singleton instance = new Singleton();
}
public static Singleton getInstance() {
return SingletonInner.instance;
}
} mh_sh_highlight_all('java');
Singleton For DirContext For LDAP Configuration
Aug 9, 2013I want to create a singleton for DirContext for LDAP configuration, hence i have used the initialize on demandclass holder idiom as shown below
public class SlmApplicationContext {
/**
* inner class to hold the instance.
*/
private static class Holder {
private static DirContext instance = new InitialDirContext();
}
/**
* Method to get the singleton instance of this class.
* @return SlmApplicationContext
*/
public static SlmApplicationContext getInstance() {
return Holder.instance; }
...
}
Now the problem is if i close the DirContext.close(), when the next request comes the singleton wont work as the dir context is already closed, hence it will create a new dir context for each requests. Which breaks the singleton concept, hence how we can ensure the singleton works fine even with DirContext.close()?
Implement Singleton - Loading Resource Bundle Only Once For JVM
Jun 20, 2014When I browsed I came to know two ways of implementing singleton.. I dont know which is best.. I am implementing this to load resource bundle only once for my jvm using constructor to getBundle.
public class bundle {
private final static Logger LOGGER = Logger.getLogger(bundle .class.getName());
private static bundle instance;
private static ResourceBundle messages;
private bundle () {
messages = ResourceBundle.getBundle("pb", Locale.getDefault());
[Code] ....
and I am calling this as bundle.getInstance.getMessage("hi");I wanted to knw which option is better and why.. and in the second case how can i call the getMessage() method?
When Close Out Singleton JFrame And Then Open It Again - Components Are Gone
Nov 30, 2014I made UpdateInmateDisplayer a Singleton so that I could access it from the private class ButtonHandler. It works to display the first inmate's number on the screen but when I close out the window and click the Book Inmate button in CurInmatesDisplayer again, it only shows a blank window. I've tried adding the components again from the ButtonHandler in CurInmatesDisplayer but it doesn't work.
View Replies View RelatedSingleton Pattern - Static Field And Public Constructor
Apr 4, 2014In singleton pattern just having a static field is not enough? Do we really need to have a private constructor?
I can have a static field and have a public constructor and still say it is singleton.
Using Factory And Singleton Design Patterns To Create A Simple Form
Nov 16, 2014My assignment was to create a simple form that demonstrates the use of the factory and singleton design patterns. "Use the Factory pattern to ensure that each form input consists of a text label and a textfield. Use the Singleton pattern for the submit button. When the submit button is clicked, a pop-up should show all the information that was typed into all of the form fields."
I used JFrame to create the form without the design patterns and I although I get the desired result, I'm not quite sure how I can integrate the design patterns into the code I wrote. The example I have to go off uses shapes, not text fields so I think that's why I'm not quite clear on how to approach this.
Here's my code so far:
import javax.swing.event.*;
import javax.swing.*;
import java.awt.*;
[Code]....
Factory And Singleton Design Patterns - Building A Simple Form
Nov 20, 2014My assignment was to create a simple form that demonstrates the use of the factory and singleton design patterns. "Use the Factory pattern to ensure that each form input consists of a text label and a textfield. Use the Singleton pattern for the submit button."
Here's what I have:
Form.java file
interface Form {
public void getFormField ();
}
Name.java file (I have a similar files just like this for Address.java, City.java, State.java, Zip.java and Phone.java)
import java.util.Scanner;
class Name implements Form
[Code] ....
It compiles at the moment but I get a null pointer exception in the main method of the FormFactoryDemo file.
Enterprise JavaBeans :: Calling Singleton Bean From Session Bean Returns NullPointerException
Feb 23, 2013I am doing this
@Startup
@Singleton
@ConcurrencyManagement(ConcurrencyManagementType.CONTAINER)
@Lock(LockType.READ)
public class ResourceBean {
[Code] ....
And I call this singleton bean from a stateless session bean like this
@Stateless
public class ClientBean {
@EJB
ResourceBean resource;
public String create(String r)
{
String res=resource.returnString(r);
return res;
}
}
But resource.returnString(r); gives a org.apache.jasper.JasperException: java.lang.NullPointerException I started the glassfish server in debug mode and found out that "resource" was null. but @PostConstruct in singleton does print which means singleton bean exists.
Can we call singleton beans with no interface in such a way form a session bean? I actually want to acquire instance of singleton bean when a client invokes method in Client bean...