JDK 131 (beta) Release Notes in Java

Creation USS Code 39 in Java JDK 131 (beta) Release Notes
JDK 131 (beta) Release Notes
Create Code 39 In Java
Using Barcode printer for Java Control to generate, create Code39 image in Java applications.
310 Serial Version UID
Bar Code Generation In Java
Using Barcode drawer for Java Control to generate, create bar code image in Java applications.
Automatic handling of class versioning only happens if both the old and the new version of the class have the same serial version unique identifier If they do not, a javaioInvalidClassException is thrown The serial version unique identifier (SUID) of a class is a 64 bit hashcode computed from all the class's properties: its classname, the names of all interfaces which it implements, and the names and signatures of its member functions and fields The SUID is identical for all versions of a class which are compatible under serialization The SUID of a class being serialized is transmitted in the output stream On arrival, the transmitted SUID is compared with the SUID of the locally installed class, in order to establish whether the class used to serialize the transmitted object is serialization compatible with the class used to de serialize it Practically any change to a class which affects its specification affects its computed SUID Accordingly, by default the serialization system will treat any such changes as incompatible with the previous version Compare the list of properties which go to determine a class's SUID with the list of limitations of automatic class versioning: you can do a lot to a class without breaking automatic versioning, but any such change will alter its SUID 3101 Defining your own SUID A class may, and should, define its own SUID:
Bar Code Scanner In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
static final long serialVersionUID = -8342560473705257631L;
Encode Code 39 Extended In C#.NET
Using Barcode drawer for VS .NET Control to generate, create Code 3/9 image in .NET applications.
Doing so has two important purposes 1 Defining the SUID at compile time avoids computing it at run time The SUID is computed by "introspecting" the properties of the class, and then computing a secure message digest of the resulting string This process is quite slow, so defining the SUID has a distinct effect on the performance of serialization 2 Classes which have been versioned must always provide a SUID: not their own, but the SUID of the original class with which they are compatible under serialization This overrides the default SUID run time computation, which is practically certain to (a) compute a different SUID for the modified class as described above, and hence (b) treat the versioned class as incompatible with the original If the versioned class provides the original class's SUID, the serialization system treats the two classes as compatible Note: this still doesn't mean that they are compatible, since this depends on what changes were actually made If you've done something naughty like deleting a field, you will find out: a serialization exception will be thrown In practice, this means that to avoid (a) poor performance under serialization and (b) future versioning difficulties, every serializable class should declare its SUID in its first version The SUID of a class is obtained by using the serialver program provided in the Java Development Kit See the JDK documentation for your system's operating instructions for serialver[13]
Create Code 39 In VS .NET
Using Barcode generation for ASP.NET Control to generate, create Code 39 Full ASCII image in ASP.NET applications.
[13]
Code39 Generation In .NET
Using Barcode generation for .NET Control to generate, create Code 39 Full ASCII image in VS .NET applications.
You should obtain the SUID from the serialver program Strictly speaking, you can use any number you like, as you're supplying it, but using the one supplied by serialver provides maximum uniqueness among the SUIDs for different classes In non Sun implementations of Java, a different means of obtaining SUIDs may be provided 3102 Examples class versio ning The initial version of a class might look like Example 31
Encode Code-39 In VB.NET
Using Barcode generation for VS .NET Control to generate, create Code 3/9 image in .NET applications.
Example 31 CustomerNameAddress original version public class CustomerNameAddress implements Serializable { static final long serialVersionUID = -8342560473705257631L; private private private private private private // } String String String String String String name; addressLine1; addressLine2; zipCode; state; country;
Encode Code-39 In Java
Using Barcode encoder for Java Control to generate, create Code-39 image in Java applications.
If later we need to add a data field the addressLine3 field in a backwards compatible way, it might look like Example 32 Note that we can add a field anywhere, not just at the end, and note that
Print DataMatrix In Java
Using Barcode drawer for Java Control to generate, create Data Matrix image in Java applications.
we didn't update the suid field A further revision might look like Example 33 We have added two more fields: homePhone and fax Note that again we didn't disturb the original suid Finally, note that, apart from defining the suid in the original version, we didn't have to write a single line of code anywhere to implement automatic versioning across these three versions of the class We didn't have to provide readObject and writeObject methods; if we had provide them in the correct form (ie starting with defaultReadObject or defaultWriteObject calls respectively), we wouldn't have to modify them for each revision
Paint UPC-A Supplement 2 In Java
Using Barcode printer for Java Control to generate, create UPC Symbol image in Java applications.
Example 32 CustomerNameAddress 1st revision public class CustomerNameAddress implements Serializable { static final long serialVersionUID = -8342560473705257631L; private private private private private private private // } String String String String String String String name; addressLine1; addressLine2; addressLine3;// added in evision 2 zipCode; state; country;
EAN-13 Supplement 5 Creator In Java
Using Barcode maker for Java Control to generate, create EAN13 image in Java applications.
Example 33 CustomerNameAddress 2nd revision public class CustomerNameAddress implements Serializable { static final long serialVersionUID = -8342560473705257631L; private private private private private private private private private // } String String String String String String String String String name; addressLine1; addressLine2; addressLine3;// added in revision 2 zipCode; state; country; homePhone;// added in revision 3 fax; // added in revision 3
UCC-128 Creation In Java
Using Barcode drawer for Java Control to generate, create GS1 128 image in Java applications.
In contrast, externalization implementing the Externalizable interface leaves all provision for class versioning in the hands of the implementor It is up to you
ANSI/AIM Code 93 Encoder In Java
Using Barcode creation for Java Control to generate, create Code 93 image in Java applications.
Draw Code128 In C#
Using Barcode encoder for .NET Control to generate, create Code 128 Code Set A image in Visual Studio .NET applications.
Code39 Generator In Visual Studio .NET
Using Barcode drawer for .NET framework Control to generate, create ANSI/AIM Code 39 image in VS .NET applications.
Reading Barcode In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
Reading Data Matrix ECC200 In Visual Studio .NET
Using Barcode reader for VS .NET Control to read, scan read, scan image in .NET framework applications.