Skip to main content

Why Marker Interface Does Not Have Method Declarations?

Every Java programmer knows that Marker Interface does not have any methods in it. Some of you confused if there are no any method declarations, and then what is the use of Marker Interface or Tagged Interface. But very few people know why we use Marker Interface and its use in our programs.

Whenever any class implementing some Marker Interface, just we are telling to JVM to do that particular functionality of interface. So JVM checks that class or it's super class is implementing the Serializable interface or not. That means serialization process is taken care by JVM itself. So you no need to write any code for serialization. Then what is the use of method declarations in Serializable interface when JVM is going to do everything for us.


So, by implementing Serializable interface we are telling to JVM that the object of the class can be seriliazable and do the rest of thing.

Example 1: For instance take Serializable interface. We know that to make an object serializable that class or its super class MUST implenet Serializable Marker Inetrafce. If we are serializing the object,..it means we are telling to JVM to serialize the object. So JVM checks that class or it's super class is implementing the Serializable interface. That means serialization activity is taken care by JVM itself. So you no need to write any code for serialization. Then what is the use of method declarations in Serializable interface when JVM is going to do everything for us.

Example 2: Cloneable Interafce. This interface is implemented by the JVM itself and allows copies of objects to be created. This means developer does not need to write any code to clone the object.
Hence Marker Interfaces are used to enable the capability of a class as implementing a specific interface at run-time.

Hope my understanding is correct and if anyone of you know more about it please write about on Marker Interface in comments section. Thanks in advance.
Labels:

Comments

Post a Comment

Popular posts from this blog

Java Health Center - Overview and Features

This video highlights the features available in Health Center. Health Center is a low-processor and memory usage diagnostic tool for monitoring the status of a running IBM Java Virtual Machine (JVM). Health Center provides live information and recommendations in each of the following areas: - Classes: information about classes being loaded - Environment: details of the configuration and system of the monitored application - Garbage Collection: information about the Java heap and pause times - Locking: information about contention on inflated locks - Profiling: sampling profile of Java methods including call paths
Post a Comment
Continue Reading >>>>

WebSphere MQ Interview Questions

What is MQ and what does it do? Ans. MQ stands for MESSAGE QUEUEING. WebSphere MQ allows application programs to use message queuing to participate in message-driven processing. Application programs can communicate across different platforms by using the appropriate message queuing software products. What is Message driven process? Ans . When messages arrive on a queue, they can automatically start an application using triggering. If necessary, the applications can be stopped when the message (or messages) have been processed. What are advantages of the MQ? Ans. 1. Integration. 2. Asynchrony 3. Assured Delivery 4. Scalability. How does it support the Integration? Ans. Because the MQ is independent of the Operating System you use i.e. it may be Windows, Solaris,AIX.It is independent of the protocol (i.e. TCP/IP, LU6.2, SNA, NetBIOS, UDP).It is not required that both the sender and receiver should be running on the same platform What is Asynchrony? Ans. With messag...
11 comments
Continue Reading >>>>

Java Garbage Collection

Explain Garbage collection mechanism in Java? Garbage collection is one of the most important features of Java. The purpose of garbage collection is to identify and discard objects that are no longer needed by a program so that their resources can be reclaimed and reused. A Java object is subject to garbage collection when it becomes unreachable to the program in which it is used. Garbage collection is also called automatic memory management as JVM automatically removes the unused variables/objects (value is null) from the memory. Every class inherits finalize() method from java.lang.Object, the finalize() method is called by garbage collector when it determines no more references to the object exists. In Java, it is good idea to explicitly assign null into a variable when no more in use. In Java on calling System.gc() and Runtime.gc(), JVM tries to recycle the unused objects, but there is no guarantee when all the objects will garbage collected. Garbage collection is an automatic pro...
Post a Comment
Continue Reading >>>>