difference between marker and tag interface

Hi friend,

nterface Definition
visibility mode interface interfaceName{
constant variable declarations
abstract method declarations
}

e.g.

public interface RacingCar{
public void startcar (int Obj);
public void changegear (int Obj);
public void incrrace (int Obj);
public void stopcar (int Obj);
}

Marker Interface

In java language programming, interfaces with no methods are known as marker interfaces. Marker interfaces are Serializable, Clonable, SingleThreadModel, Event listener. Marker Interfaces are implemented by the classes or their super classes in order to add some functionality.

e.g. Suppose you want to persist (save) the state of an object then you have to implement the Serializable interface otherwise the compiler will throw an error. To make more clearly understand the concept of marker interface you should go through one more example.

For more information visit to :

http://www.roseindia.net/java/master-java/interface.shtml

Thanks

Hi friend,

Tag interface

The Tag interface defines the basic protocol between a Tag handler and JSP page implementation class. It defines the life cycle and the methods to be invoked at start and end tag.

There are several methods that get invoked to set the state of a Tag handler. The Tag handler is required to keep this state so the page compiler can choose not to reinvoke some of the state setting.

marker interface

The marker interface pattern is a design pattern in computer science, used with languages that provide run-time type information about objects. It provides a means to associate metadata with a class where the language does not have explicit support for such metadata.

To use this pattern, a class implements a marker interface, and methods that interact with instances of that class test for the existence of the interface. Whereas a typical interface specifies functionality (in the form of method declarations) that an implementing class must support, a marker interface need not do so. The mere presence of such an interface indicates specific behavior on the part of the implementing class. Hybrid interfaces, which both act as markers and specify required methods, are possible but may prove confusing if improperly used.

An example of the application of marker interfaces from the Java programming language is the Serializable interface. A class implements this interface to indicate that its non-transient data members can be written to an ObjectOutputStream. The ObjectOutputStream private method writeObject() contains a series of instanceof tests to determine writeability, one of which looks for the Serializable interface. If none of these tests pass, the method throws a NotSerializableException.



Thanks.