serializable

If you have ever implemented Serializable interface, you must encounter this warning message The serializable class xxx does not declare a static final serialVersionUID field of type long intro. So…what is serialVersionUID? The serialVersionUID is used as a version control in a Serializable class. 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 . 1. SerialVersionUID Example The above statement is a bit hard to understand at the

Is it mandatory to implement Serialize for Java DTO/Model objects? If so why? If not whats the impact on performance etc? A DTO is normally a Data Transfer Object. It doesn't have to use Java Serialization, but if it doesn't it needs to follow some other convention. Its not a matter of performance as if you are using Java Serialization it most likely has to be Serializable (or Externalizable which is still Serializable) Not if you're not saving them to a file or sending them across a socket. There's nothing about a DTO that requires serialization. The need for serialization will depend on your

I'm trying to get my clipboard to receive some custom data in a drag and drop. The custom data is another java type. This other type does implement serializable, so I'm really not sure why this isn't working. Any ideas are appreciated! imgView.setOnDragDetected(new EventHandler<MouseEvent>() { public void handle(MouseEvent event) { ClipboardContent content = new ClipboardContent(); content.put(dataFormat, RHSIconizedToken.this); Dragboard db = imgView.startDragAndDrop(TransferMode.ANY); db.setContent(content); event.consume(); } }); To retrieve this object later I'm using: RHSIconizedToken

It has baffled me from the launch of the Serializable interface why I have to incorporate this field in all of my classes. I understand that this interface needs a unique identifier to mark the class but why cant they generate this at run-time. For instance they could generate it using an MD5 hash of the fully-qualified class name or a similar methodology used to handle duplicates in their rare occurrence (Which is, I'm sure, what eclipse does when asked to generate the id anyway). So what I'm asking (no this post isn't just a rant against the standard library) is exactly how the serialization

This is the code that I have been trying import java.util.Scanner; import java.io.*; abstract class Account implements Serializable { protected String accountHolderName; protected long balance; protected ObjectOutputStream accData; Scanner input = new Scanner(System.in); } class Savings extends Account implements Serializable { Savings() throws IOException { System.out.print("enter your name: "); accountHolderName = input.nextLine(); System.out.print("\n"); System.out.print("enter your balance: "); balance = input.nextLong(); accData = new ObjectOutputStream(new FileOutputStream

（PS:本文为作者原著，如需转载，请注明出处-_^） 使用java以来，序列化随处可见，至于为什么要用序列化、序列化能解决什么问题，作为一个普通的码农，一般不怎么会去深入研究，由于最近在看mina和公司内部涉及到nio框架的一些源码，里面涉及到hession、java这两种序列化，至于hession序列化为什么会诞生以及在apache项目中使用如此广泛，以及java本身序列化存在哪些缺陷，甚是不解，为了解答上面抛出来的疑惑，以及进一步了解java的序列化机制，这里开个小头，从java的序列化接口Serializable开始说起 jdk包里的Serializable接口的注释主要说明了以下几点： 1.类通过实现 Serializable接口来启用序列化，否则该类的任何状态将无法被序列化，同时也无法用于反序列化 2.若继承的父类没有实现 Serializable接口，但是又想让子类可序列化，有三个注意事项： a).子类实现Serializable接口 b).子类必须有可访问的无参构造方法，用于保存和恢复父类的public或protected或同包下的package字段的状态，否则在序列化或反序列化时会抛出RuntimeException异常 c).对于序列化后的子类，在进行反序列化时，理论上无法初始化父类中private（不可访问）对象变量的状态或值 3

I am writing a .NET Remoting application. I have my dll, server, and client all working correctly. However, when I try to change my method call to take an object parameter instead of a simple type like an int, it complains with this error. Type System.Runtime.Remoting.ObjRef and the types from it (such as System.Runtime.Remoting.ObjRef) are not permitted to be deserialized at this security level. The method is something like this. public List<Orders> GetOrders(int UserID) { //Works public List<Orders> GetOrders(Users user) { // Doesnt Work [Serializable] public class Users : MarshalByRefObject

I am facing a strange issue with Scala/Spark (1.5) and Zeppelin: If I run the following Scala/Spark code, it will run properly: // TEST NO PROBLEM SERIALIZATION val rdd = sc.parallelize(Seq(1, 2, 3)) val testList = List[String]("a", "b") rdd.map{a => val aa = testList(0) None} However after declaring a custom dataframe type as proposed here //DATAFRAME EXTENSION import org.apache.spark.sql.DataFrame object ExtraDataFrameOperations { implicit class DFWithExtraOperations(df : DataFrame) { //drop several columns def drop(colToDrop:Seq[String]):DataFrame = { var df_temp = df colToDrop.foreach{