How To Get Serialversionuid In Java

Hello, We are migrating from Hybris 5. This will generate Java classes in your project folder and you should be able to find them in the folder named classes,. I spent three hours trying to get an applet working. Using this , it becomes very easy to create Bar chart, Linear Chart, Pie chart etc. Serialization is a marker interface. For reactive streams style programming, see the Flow API. My objective is to parse this file, substitute the variables present in this file…. They both get called in sequence and never use the connection in parallel. Check out this post to learn everything you need to know about serialization in Java and All transient and static fields do not get serialized. An applet is typically embedded inside a web-page and runs in the context of the browser. Whenever you write a Java class in Eclipse which implements java. Object class does not implement that interface. In this post, we are going to explore an important Java concept frequently asked during Job's interviews i. Serializable; public class Address implements Serializable{ private static final long serialVersionUID = 1L; String street; String country; public void setStreet(String street){ this. This project adds Tasks and FilterReaders to get, to insert and to modify the serialVersionUID in the source code of a serializable class. The only way to get rid of the exception is to recompile and deploy the application again. SerialVersionUID with "private static final long" still gets InvalidClassException stackoverflow. Enter JavaMag for the name of the project and click Next. Object with javax. With over 16 millions+ pageviews/month, Crunchify has changed the life of over thousands of individual around the globe teaching Java & Web Tech for FREE. Get the type of this extensibility element. A coworker said that all classes must have a unique serial version uid and that the jvm will treat classes as equal if they have the same serial version uid. With Eclipse, you get the warning all the time, and you can choose between: ignoring it; adding the annotation @SuppressWarning("serial") generating the serial version id. StringUtils. After reading your article about “How Deserialization Process Happen in Java”, I get confused or you can say get more thoughts to think about deserialization process. then if you use soapUI to generate the request for you, you'll get something like this and the result will be (in your server logs) [Thing [name=aeoliam venit, date=Sun Sep 28 22:49:45 BRT 2008, longg=10]]. serialVersionUID in Java Serialization Last modified on September 12th, 2014 by Joe. In this post we will see what is serialVersionUID in java and why should we use it. It is used to get serialVersionUID numbers of one or more Java classes. Here’s the Simple Text Application source code I hope you wouldn’t get…. Then the other computer can check the frame's version number to make sure that no. Introduction While answering questions on the Hibernate forum, I stumbled on the following question about using the @ManyToOne annotation when the Foreign Key column on the client side references a non-Primary Key column on the parent side. If you are using Java 7, you can generate serialVersionUID like this: private static final long serialVersionUID = 2014_04_17_001L; Whenever you make a change to the class, update the date / version. 1 and it is one of the important feature of Core Java. In order to avoid this ,make sure that threads acquire the needed locks in same order so that one thread is able to complete its task and releases the locks and after that other thread can resume its processing. You'll learn about the serialization algorithm used in Java, and see an example that illustrates the serialized format of an object. serialVersionUID is a must in serialization process. It not only checks if the String is not empty and not null, but also checks if it is not only a whitespace string. get方法吗? 显示全部. The docs for java. The toString method returns a printable representation of the class descriptor including the class's name and serialVersionUID. Java Serialization allows us to convert Java Object to a Stream of bytes which we can send through a network or save in a flat file or even in a DB for future usage. Serializing data translates it into a storable form that can be converted back to original form. jar against commons-csv-1. BindingException extends PersistenceException implements Serializable serialVersionUID. ConcurrentHashMap A simple map with the option to add, get, remove and get the size of the Map could be implemented like the following. To set the console font, go to General Appearance Colors and Fonts "Debug" line. Serializable are probably about as good an explanation as you'll get:. If i change text field to 10/07/09 i still get the 20/07/09. if see "random looking" explicit serialversionuid, it's been generated ide, typically starting off uid have been generated if explicit version hadn't been provided. Http session in servlet example program code : HttpSession is an interface that provides a way to identify a user in multiple page requests. The serialized object will contain this serialVersionUID along with other data. As well as the rest of the class for that matter. With Eclipse, you get the warning all the time, and you can choose between: ignoring it; adding the annotation @SuppressWarning(“serial”) generating the serial version id. For the sake of test REST API easily. How to get the method name from a java 8 lambda using serialization hacks - Main. Therefore, not all the objects in Java can be persisted automatically. concurrent package. The serialVersionUID is used as a version control in a Serializable class. if see "random looking" explicit serialversionuid, it's been generated ide, typically starting off uid have been generated if explicit version hadn't been provided. This mechanism is used to persist the object. During serialization, java runtime associates a version number with each serializable class. Get latest update on and. Enter the full class name and press either the Enter key or the Show button to display the serialVersionUID. Random class in Java. For example, you can send the state of your JFrame object to another computer's screen. Long #453 Closed detollenaere opened this issue Jul 28, 2017 · 13 comments. The main goal of this interface is to facilitate custom serialization and deserialization. You can search forum titles, topics, open questions, and answered questions. Develope a programme, read password from keyboard,find is it in the below pattern or not. Always Declare Serial Version Uid This is one of the JavaIdioms You're making a class serializable. java in src->org. Edit, and choose the font size. Displays a simple user interface. Short question: how to discover the serialVersionUID of Objects that are in serialized form. Why worry about this if Java takes care of this ? If we are using Eclipse IDE and after we implement java. If you aren't careful with streams in Java, you end up with resource leaks. This is called “to throw an exception” because in Java you use the keyword “throw” to hand the exception to the runtime. Whenever you change a class in a way that breaks the normal >serialization mechanism, you should increase the serialVersionUID of >the class and implement readObject (no need to implement writeObject) >to be able to read objects of both class versions. Whenever a class implements the Serializable interface, most IDE's like eclipse, IntelliJ Idea generates the serialVersionUID field which is static, final, and of type long. If a Serializable class without a serialVersionUID has already been shipped in a release, running the serialver tool on the type in the shipped release will return the serialVersionUID declaration needed to maintain serial compatibility. When invoked with -show it puts up a simple user interface. The second way is to replace java. I can get it working with a normal submit button but when i try anything with ajax i get the problem stated. java ***** import java. This Java tutorial helps you understand object serialization in Java, why you need it, how it works, when to use it, related concepts (serialVersionUID and transient), and other necessary information about serialization and deserialization. you will use the Java's built-in graphics and containers, combined with a simple framework that we provide. How do I get the location of my web application context in the file system? Author: Deron Eriksson Description: This tutorial describes how to use the ServletContext to get the location of the web application context directory in the file system. This is an excerpt from the Scala Cookbook (partially modified for the internet). jar such as. The list below shows all methods and their purpose. For serializable classes the SerialVersionUid should be written explicitly. but why? answer is because IDE force to do that. Therefore, not all the objects in Java can be persisted automatically. Every Java application whether its simple standalone or multi aspect complex enterprise java web application it will rely on some static properties file. Hello!!! Someone know what signify the serialVersionUID variable and why if you don't declare it the eclipse enviroment produces a warning? private static final long serialVersionUID = 1L; Thanks!!!. > how fo i generate serialversionuid from eclipse ? there is a tool in > jdk serialver. InvalidClassException will be thrown, and print out the name of the class and the corresponding SerialVersionUID. In this tip, you will see how to serialize an object, and why serialization is sometimes necessary. If during deserialization, SerialVersionUID do not match, the deserialization process will fail, and at the same time, a java. questions > how can i convert a byte array to an object ? final long serialVersionUID = 1L;. You can search forum titles, topics, open questions, and answered questions. With Eclipse, you get the warning all the time, and you can choose between: ignoring it; adding the annotation @SuppressWarning(“serial”) generating the serial version id. And that is the case for most Java objects that you need to close. pdfbox pdfbox 2. It is also possible to instantiate new objects, invoke methods and get/set field values using reflection. SecurityBean final static long serialVersionUID = 3206093459760846163L; I know that this variable is typically used during Java object serialization. If they are different they are considered incompatible and an Exception is thrown. But it is optional for the developer to add it in java source file. hibernate-3. The Java Serialization API provides a standard mechanism for developers to handle object serialization. Directly quoting from Javadocs here, since it probably describes SerialVersionUID in best manner :The serialization runtime associates with each serializable class a version number, called a serialVersionUID, which is used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible with respect to serialization. As mentioned before, only objects marked Serializable can be persisted. We use JSON for RPC calls and my guess is that the serialization happens at network behind the scenes. serialVersionUID を設定する オブジェクトの serialize を行う場合に、 serialVersionUID を設定する必要がある場合があります。 Java の serialver. Love SEO, SaaS, #webperf, WordPress, Java. If we explicitly mention the sUid using the statement: private final static long serialVersionUID = then if any of the metioned compatible changes are made the class need not to be recompiled. Serializable interface to make a class serializable, the compiler looks for a static, final field named "serialVersionUID" of type long. Inspecting Serializable Classes The program serialver can be used to find out if a class is serializable and to get its serialVersionUID. You can create custom exceptions in Java. Java Serialization. This compensation may impact how and where products appear on this site including, for example, the order in which they appear. Deserialization is the process of converting a stream of bytes back to Java Object which can be used in our program. Java run-time associates with each serializable class a special version number known as serialVersionUID. What is serialVersionUID. If you do not add serialVersionUID to the java source file, then serialization runtime will generate a serialVersionUID and associate it with the class. At the time of de-serialization, If the receiver has loaded a class for the object that has a different serialVersionUID than that of the corresponding sender's class. For the sake of test REST API easily. exe を使用しても良いのですが、面倒なので、 Eclipse プラグインの serialVer を利用すると便利です。. Object implements Serializable serialVersionUID:-3133792315497822421L. java newsgroups. In this guide, we will understand the usage of serialVersionUID in Serialization. IllegalAccessException: Can not set static final long field xxx. A mandatory requirement for a class object to be able to be serialized in Java is that the class should implement Serializable interface which is part of java. Thats why the java runtime chose to have such a complex algorithm to generate it. Advantages of Java Serialization. This will help you in revising most asked interview questions for developers. This problem can be corrected by modifying the last 3 or 4 digits of the serialVersionUID that was generated for the bean and primary key classes. The standard Java interfaces for maps is import java. I have two java classes which implement Serializable. Java Servlets are basically objects which sends back a response based on the incoming request. Serializable interface, you'll get this warning:. street = street; } public void setCountry(String country){ this. Serializable are probably about as good an explanation as you'll get:The serialization runtime associates with each serializable class a version number, called a serialVersionUID, which is used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible with respect to serialization. java The AWS Documentation website is getting a new look! Try it now and let us know what you think. An applet is typically embedded inside a web-page and runs in the context of the browser. java in src->org. you will use the Java's built-in graphics and containers, combined with a simple framework that we provide. initNonProxy ( Unknown Source ) at java. Is this a bug or a feature or am I just blind?. private --->encasulation we can not use this variable in other class static ---->no need to create object to call this variable final ---->we can not change the variable value long ----->type of the variable if we use long we need to declare L serialVersionUID ---> variable name. The version number is SerialVersionUID. There are a lot of third web services on the internet. import java. The canonical reference for building a production grade API with Spring. Watch Queue Queue. In this article you will learn how to get data from an HTML page in a servlet. You can assign any number to it. AnycastAddress extends java. " The general approach is the same as Java, but the syntax to make a class serializable is different. If you do not explicitly declare a serialVersionUID, JVM will do it for you automatically, based on various aspects of your Serializable class, as described in the Java(TM) Object Serialization Specification. Please note that even in Java 8, int is signed. Inspecting Serializable Classes The program serialver can be used to find out if a class is serializable and to get its serialVersionUID. Introduction I am going to show how to perform undo algorithm on your Java Swing application. A unique session id is given to the user when first request comes. hibernate-3. serialVersionUID is adding a version number to make sure the serialized Get unlimited access to the best. AnycastAddress extends java. Java Reflection is quite. Compile your project without the serialVersionUID first. A distributed system is a program or set of programs that runs on more than one computing resource. @WebFilter Annotation has been introduced in Java EE 6. This is called “to throw an exception” because in Java you use the keyword “throw” to hand the exception to the runtime. 1k points) How do generate this value in IntelliJ IDEA? I go to Settings -> Errors -> Serialization issues -> Serializable class without 'serialVersionUID', but it still doesn't show me the warning. That's all for this topic SerialVersionUID And Versioning in Java Serialization. Oracle offers a comprehensive and fully integrated stack of cloud applications and platform services. How to get the method name from a java 8 lambda using serialization hacks - Main. If you have a function in a class, it can only be called on instances of this class. With over 16 millions+ pageviews/month, Crunchify has changed the life of over thousands of individual around the globe teaching Java & Web Tech for FREE. HashMap or import java. I hope the above information helps get this problem fixed in the next version of Drizzle , when you get the chance to read my post and reply back about it if you ever online again, thanks again for this new version of the software, I really thought Drizzle 31 was going to be the last version because the project got stopped an long time ago. This is Recipe 12. declared serializable but don't specify a serialVersionUID. Java Reflection is quite. I'm dealing with some really old Java code in Eclipse with several classes that implement serializable but do not have a serialVersionUID defined. These two variables construct the confirmation url. This is an excerpt from the Scala Cookbook (partially modified for the internet). Oracle Java Cloud Service currently supports a mix of technologies from Java EE 5 and Java EE 6. 0 incompatibilities in the Sun JDK. Eg1: Assume you have a Java bean object and its variables are having some values. The standard Java interfaces for maps is import java. PDF example 3. If a serializable class does not explicitly declare a serialVersionUID, then the serialization runtime will calculate a default serialVersionUID value for that class based on various aspects of the class, as described in the Java(TM) Object Serialization Specification. If you have a function in a class, it can only be called on instances of this class. After I added this static final long serialVersionUID = 42L; It started working. 10年 Java程序员,硬核人生!勇往直前,永不退缩! 深圳找工作,10年 Java程序员,硬核人生! 寻求一份有挑战有激情的牛逼. After reading your article about "How Deserialization Process Happen in Java", I get confused or you can say get more thoughts to think about deserialization process. Love SEO, SaaS, #webperf, WordPress, Java. This class is for throwing important checked exceptions over non-checked methods. During serialization, java runtime associates a version number with each serializable class. serialVersionUID is a field to define the version of a particular class while seriializing & deseriializing. Now we have created notepad by help of java Swing programming language. You can extend the project’s handling of call operations, which it was instructed to perform by a Jacada Interaction Manager script. Hi, I have serialized Weka Classifiers months ago, using a previous version of Weka. Java Serialization. Java provides a mechanism, called object serialization where an object can be represented as a sequence of bytes that includes the object's data as well as information about the object's type and the types of data stored in the object. Setting it explicitly in the class is an indication that the class will deal with changes on its own (since the normal serialVersionUID computation is quite draconian - adding a new public method or changing an existing method to final would break serialization by producing a new serialVersionUID). Serializable …、ある程度Javaに触れて来た人は必ず見たことがあるインターフェイスだと思う。私も何度も見てきたし、必要に迫られて自分の作ったクラスにSerializableをつけたこともある。. That changed when Java 7 introduced the try-with-resource statement. Serialization runtime generates a serialVersionUID if you do not add one in source. After I added this static final long serialVersionUID = 42L; It started working. Long #453 Closed detollenaere opened this issue Jul 28, 2017 · 13 comments. Detail: I have some serialized versions of Objects in a session database for a web application. serialVersionUID is a must in serialization process. Notice that the url in the AJAX request maps to the path property in the SlingServlet annotation. You also want the OSGI bundle to have its settings editable in the Felix Console. The serializable class XXXX does not declare a static final serialVersionUID field of type long. asked Aug 17 in Java by Anvi (6. If you're using a very popular Java development IDE IntelliJ IDEA, you may find it not straightforward, how to generate the serialVersionUID there. The Java class that you create in this section extends the Sling class named org. Thanks! Related Topics. Java serialVersionUID - How to generate serialVersionUID By Lokesh Gupta | Filed Under: Java Serialization Java serialization is the process of converting an object into a stream of bytes so we can do stuff like store it on disk or send it over the network. Similar, if superclass is serializable then subclasses will also serialized. Each type of exception that. beans package. But it is optional for the developer to add it in java source file. When we Serialize a class , then change the class i. The program works well, but I am looking for feedback in. */ private static final long serialVersionUID = 7526471155622776147L; /** * Always treat de-serialization as a full-blown constructor, by * validating the final state of the de-serialized object. After I added this static final long serialVersionUID = 42L; It started working. Hello, my name is Alvin Alexander, and I wrote the Scala Cookbook for O'Reilly. pdfbox pdfbox 2. Understand when to serialize v. Serializable 104 { 105 private static final long serialVersionUID. consider a scenario where you have a class Employee which has 3 fields which has been in production for some time (meaning there may exist many serialized versions of employee objects), when you update the class to include (say a 4th field) then all the previous class (which are. Serializable are probably about as good an explanation as you'll get:. In Java arithmetic. That's all for this topic SerialVersionUID And Versioning in Java Serialization. All serializable Java objects (that is, objects which implement the marker interface java. InvalidClassException. This property file goes through constant changes by the hands of developers, deployment and configuration managers. Develope a programme, read password from keyboard,find is it in the below pattern or not. That means the Java compiler will generate one if you don't explicitly declare it. Please follow the How to create and package a module section to create a new module. If serialVersionUID is not declared in the class and if there is any incompatible modification made in class, then we would not be able to deserialize this class as serialVersionUID generated by java compiler for modified class will be. It internally converts the object in stream of bytes. Java warning - Serializable class without serialVersionUID. The serialization runtime associates with each serializable class a version number, called a serialVersionUID, which is used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible with respect to serialization. 直列化可能クラスがserialVersionUIDを明示的に宣言しない場合、直列化ランタイムは「Java(TM)オブジェクト直列化仕様」で説明されているように、クラスのさまざまな側面に基づいて、クラスのserialVersionUIDのデフォルト値を計算します。. The serialVersionUID is used to verify that. EmailInfo: static final long serialVersionUID = -4312319268131871162L;. subas kumar tosh April 14, 2015 at 8:24 pm. If i change text field to 10/07/09 i still get the 20/07/09. For some of these objects, I failed to specify a serialVersionUID in the source code so the JVM created one for me. If you leave out a serialVersionUID java will generate one for the class at compile time (it changes with every compilation). How to create Notepad in Swing. In Java whenever a class implements java. Serializable - interface, and class contain field : private static final long serialVersionUID = 3653681193556495215L;. First, select New -> Java EE -> Enterprise Application. It not only checks if the String is not empty and not null, but also checks if it is not only a whitespace string. Notice that the url in the AJAX request maps to the path property in the SlingServlet annotation. Solution Run serialver and paste its output into your classes before you start. import java. If you have one version of the object on one computer that has the attribute added or removed, and the object gets remoted to a computer with a version of the object where the attribute is either missing or expected, things can get weird. WARNING: You are using the option '--ignore-missing-classes', i. When I try to run the below servlet code using eclipse IDE, I could not able to retrieve hive table data even though I dint get any errors when running the code. using IBM VisualAge for Java, version 3. Installing a 64-bit JDK does NOT install Java support in the 32-bit browser in 64-bit operating systems. If you are using Java 7, you can generate serialVersionUID like this: private static final long serialVersionUID = 2014_04_17_001L; Whenever you make a change to the class, update the date / version. 0 and later Information in this document applies to any platform. If we explicitly mention the sUid using the statement: private final static long serialVersionUID = then if any of the metioned compatible changes are made the class need not to be recompiled. But it is optional for the developer to add it in java source file. This compensation may impact how and where products appear on this site including, for example, the order in which they appear. Before we go ahead, make sure you check out the. -Joption Pass option to the Java virtual machine, where option is one of the options described on the reference page for the java application launcher. If you do not add serialVersionUID to the java source file, then serialization runtime will generate a serialVersionUID and associate it with the class. serialVersionUID is adding a version number to make sure the serialized Get unlimited access to the best. As mentioned before, only objects marked Serializable can be persisted. This is an excerpt from the Scala Cookbook (partially modified for the internet). Serializable, we will notice a warning "didn't declare a static final serialVersionUID of type long". The canonical reference for building a production grade API with Spring. The _001 means it is the first version on that date. In Java arithmetic. The serialization runtime associates with each serializable class a version number, called a serialVersionUID, which is used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible with respect to serialization. Serialization: It is a process of writing an Object into file along with its attributes and content. Then we need to pass that object as the parameter to load the object. they will not run at all. The _001 means it is the first version on that date. Serializable is a marker interface your classes must implement if they are to be serialized and deserialized. SerialVersionUID is optional. static final long serialVersionUID = ; If we do not do this explicitly, then during class compilation, Java Serialization runtime will calculate a default SUID for that class automatically based on various aspects of the class, as described in the Java(TM) Object Serialization Specification. exe を使用しても良いのですが、面倒なので、 Eclipse プラグインの serialVer を利用すると便利です。. Is this a bug or a feature or am I just blind?. For serializable classes the SerialVersionUid should be written explicitly. How to configure primary key's generator in JPA entity for oracle Sheng Wang 5:42 PM JPA , Oracle 4 Comments In JPA there are 4 strategies to automatically generate value for a primary key column:. Java Servlets are basically objects which sends back a response based on the incoming request. If you have a function in a class, it can only be called on instances of this class. wsdl2java takes a WSDL document and generates fully annotated Java code from which to implement a service. Why worry about this if Java takes care of this ? If we are using Eclipse IDE and after we implement java. In this article you will learn how to get data from an HTML page in a servlet. If they are different they are considered incompatible and an Exception is thrown. [code]import java. So you make it implement the Serializable interface. You use the try/catch statement to catch exceptions and the throw statement to throw exceptions. jar such as. but why? answer is because IDE force to do that. People like to concoct flavourful terminology to describe the saving (pickling, free drying, swizzling) and restoring (depickling, deswizzling, reconstituting) processes. First Last Prev Next This bug is not in your last search results. java ***** import java. Overflow and Underflow in Java int operators Arithmetic integer operations are performed in 32-bit precision. Therefore, not all the objects in Java can be persisted automatically. Edit, and choose the font size. If you have any doubt or any suggestions to make please drop a comment. Now, if your class implements Serializable , you will see highlight, and alt+Enter on class name will propose to generate private static final long serialVersionUID. Understand the serialVersionUID and how to use it. If they are different they are considered incompatible and an Exception is thrown. But there are some methods that treat them as if they were unsigned but there is no way to declare an Unsigned int in Java 8 or beyond. private static. I am running a program form my book and i get this warning from eclipse that says: "The serializable class ColorWindow does not declare a static final serialVersionUID field of type long" import javax. If we don’t define serialVersionUID in the class, and any modification is made in class, then we won’t be able to deSerialize our class because serialVersionUID generated by java compiler for modified class will be different from old serialized object. The standard Java interfaces for maps is import java. The serialization runtime associates with each serializable class a version number, called a serialVersionUID, which is used during deserialization to verify that the sender and receiver of a serialized object have loaded classes for that object that are compatible with respect to serialization. If you are not going to add it in java source file, serialization runtime will generate a serialVersionUID and associate it with the class. After I added this static final long serialVersionUID = 42L; It started working. Value generated automatically can differ between various Java implementations. Object class does not implement that interface. Parse CSV File using OpenCSV. How many times you have added serialversionuid in to your code. You can create custom exceptions in Java. String: getTransportURI() Get the transport URI to be used with this binding. how to set serialVersionUID 806554 Aug 11, 2005 8:15 PM I have a problem compling my code in java 5. 0 Servlet setAttribute & getAttribute method example Building Enterprise Bean. The serialVersionUID is used as a version control in a Serializable class. Now, let's modify the serialVersionUID constant in AppleProduct. Compile your project without the serialVersionUID first. Overview of Serialization Serialization with example - ObjectOutputStream class Deserialization in java - ObjectInputStream class Java Serialization with Inheritance (IS-A Relationship) Java Serialization with Aggregation (HAS-A Relationship) Java Serialization with a static data member Externalizable in java. The canonical reference for building a production grade API with Spring. Lets see an example: Create Employee. Cannot Set Static Final Long Field Serialversionuid >> DOWNLOAD (Mirror #1) This site was designed with the {Wix} website builder. The serialized object will contain this serialVersionUID along with other data. Scanner; class Author { public String name; public BookList books. Java Forums on Bytes. Unchecked, RawTypes, Serial @SuppressWarnings annotation is one of the three built-in annotations available in JDK and added alongside @Override and @Deprecated in Java 1. Click to get started! My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts. Halo, I made some integration tests with LML library, and I see one strange exception. I am learning to use Java Swing and have made a simple animation that makes a small shape bounce around the predetermined borders of a panel. Preventing ClassCastExceptions with SerialVersionUID Problem Your class got recompiled, and you're getting ClassCastException s that you shouldn't. Serialization is a mechanism of converting the state of an object into a byte stream. Re-running DeserializationUtility. I set both of them to have a serialVersionUid of 1L. So it says you must declare serialVersionUID because it give us more control. If a serializable class does not have a serialVersionUID, the class name will be highlighted with a warning.