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Jayasanka
Name : Jayasanka Illangarathne (J)

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What is serialVersionUID?

If a class implements Serializable interface, your IDE worn you to add serialVersionUID or it add automatically. This variable holds a private static final long and IDE automatically declared it to 1L. class SerializeMe implements Serializable { private static final long serialVersionUID = 1L; private String data; public SerializeMe (String data) { this.data = data; } public String getData() { return data; } } Field data represents some information stored in the class. Note that serialVersionUID is a static value, then it should not have been serialized. But why is this so impotent? public class SerialVersionUIDTester { public static void main(String [] args) throws Exception { File file = new File("out.ser"); FileOutputStream fos = new FileOutputStream(file); ObjectOutputStream oos = new ObjectOutputStream(fos); SerializeMe serializeMe = new SerializeMe("serialVersionUID is 1L"); ...
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-- Are you a Android Developer? --

If you going to develop an application using Android (specially hardware dependent application, just like new protocol for WI-FI or new network application), curren- tly you must have a mobile phone which is fully support Android OS. There was a Nokia phone and one Motorola phone which is support to Android partially. Because some Android features doesn't work will on those phones. That implies only T-Mobile G1 is the solution to such development. Android announce that they are going to issue a phone, for Android developments and they are call it as a Android Dev Phone 1 . Android Dev Phone 1 is a SIM-unlocked and hardware-unlocked device that is designed for advanced developers. The device ships with a system image that is fully compatible with Android 1.0, so you can rely on it when developing your applications. We can use any SIM in the device and can flash custom Android builds that will work with the unlocked bootloader. The device currently costs $399 (USD) (including free sh...
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Message driven beans(MDB) and transaction attributes

"Message-driven beans may declare only the NOT_SUPPORTED or REQUIRED transaction attribute. The other transaction attributes don't make sense in message-driven beans because they apply to client-initiated transactions." Why ? MDB are called asynchronously. Therefore NEVER, SUPPORTS, REQUIRES_NEW transaction attributes are not make sense, because there isn't pre-existing transaction context for MDB. NEVER throws Exception if there is pre-existing transaction context, but that don't ever occur. If there is pre-existing transaction context, SUPPORTS will run in that transaction context. (But, there is NO such in MDB!) REQUIRES_NEW always run in new transaction context, but this behavior is always the same to REQUIRED. REQUIRED Vs. REQUIRES_NEW why are we allowed to use a REQUIRED , but not a REQUIRES_NEW? When we specify theh RequiresNew, it comes with an implicit understanding that if the client has a transaction, it needs to be suspended. i.e. the existence of a cl...
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