Java serialver command examples

The serialver is a tool that comes with JDK. It is used to get serialVersionUID numbers of one or more Java classes. Basically, a serializable class must declare a constant named serialVersionUID (either explicitly by the programmer or implicitly by the compiler) like this:

public class User implements Serializable {

	private static final long serialVersionUID = 1234L;
	
}

The serialVersionUID number is important when dealing with the serialization/de-serialization of objects of a class. The serialver command is helpful in case we want to know that number without having source code of the class. Its syntax is as simple as follows:

serialver [-classpath classpath] [-show] [classname...]

The -classpath option specifies where to look for the classes (in directories or jar files, separated by semicolon marks ;). The -show option displays a simple user interface that allows the user to enter a full class name and then press Enter key or click Show button to display the serialVersionUID number.

Now, let’s see some examples.

• Displaying serialVersionUID of a class in default package:

  Command:

  serialver ProgressBarDemo

  Output:

  ProgressBarDemo:    static final long serialVersionUID = 8449967402779341329L;

  If the specified class is not serializable, then this message is displayed:

  Class ProgressBarDemo is not Serializable.

• Displaying serialVersionUID of a class in a specific package:

  The following command displays the serialVersionUID of the class SwingEmailSender under the package net.codejava.mail, assuming that the classes are in the build\classes directory:

  serialver -classpath build\classes net.codejava.mail.SwingEmailSender

  Output:

  net.codejava.mail.SwingEmailSender:    static final long serialVersionUID = -2279575288884790698L;

   

• Displaying serialVersionUID numbers of two classes:

  Command:

  serialver CustomPanel TestSwingZoom

  Output:

  CustomPanel:    static final long serialVersionUID = 6858515184837974475L;
  TestSwingZoom:    static final long serialVersionUID = 4136458911881435009L;

   

• Displaying serialVersionUID of a class inside a jar file:

  Command:

  serialver -classpath EmailSender.jar net.codejava.swing.JFilePicker

  Output:

  net.codejava.swing.JFilePicker:    static final long serialVersionUID = -6241197264668893626L;

   

• Displaying serialVersionUID of two classes inside two jar files:

  Command:

  serialver -classpath SwingAudio.jar;SwingUpload.jar net.codejava.AudioPlayer net.codejava.FileUpload

  Output:

  net.codejava.AudioPlayer:    static final long serialVersionUID = 5499535881565379674L;
  net.codejava.FileUpload:    static final long serialVersionUID = 6409440265121275085L;

   

• Showing the user interface:

  Command:

  serialver -classpath EmailSender.jar -show

  The Serial Version Inspector window gets displayed, enter the full class name and click the Show button to display the serial version:
  

References:

• serialver - The Serial Version Command

Java Serialization Tutorials:

• Why Do We Need Serialization in Java?
• Java Serialization Basic Example
• Understanding Java Externalization with Examples

Other Java Tools Tutorials:

• javac command examples
• java command examples
• Java jar command examples
• Understanding the triad tools javac, java and jar in JDK
• The Java Shell (jshell) Tutorial
• How to compile, package and run a Java program using command-line tools (javac, jar and java)

About the Author:

Nam Ha Minh is certified Java programmer (SCJP and SCWCD). He began programming with Java back in the days of Java 1.4 and has been passionate about it ever since. You can connect with him on Facebook and watch his Java videos on YouTube.