What is marker interface explain with example?

What is marker interface explain with example?

In other words, an empty interface is known as marker interface or tag interface. It delivers the run-time type information about an object. It is the reason that the JVM and compiler have additional information about an object. The Serializable and Cloneable interfaces are the example of marker interface.

Why do we use marker interface in Java?

Marker interface is used as a tag to inform a message to the Java compiler so that it can add special behaviour to the class implementing it.

Can we create a marker interface in Java?

You can create your own custom marker interface in Java. Here is an example using custom Marker interface in Java. As we know marker interfaces define a type, that can be used with instanceof operator to test whether object is an instance of the specified type.

What is the difference between marker interface and annotation in Java?

Marker interfaces define a type that is implemented by instances of the marked class; marker annotations do not. The existence of this type allows you to catch errors at compile time that you couldn’t catch until runtime if you used a marker annotation.

What are the components of a marker interface?

It is an empty interface (no field or methods). Examples of marker interface are Serializable, Cloneable and Remote interface. All these interfaces are empty interfaces.

What is marker annotation in Java?

What is a Marker Annotation? Marker annotations are special annotations in Java that do not contain any members or data. As marker interfaces do not contain any members, just declaring the annotation in your code is sufficient for it to influence the output in whatever terms you want.

What can we use instead of marker interface?

In modern Java, marker interfaces have no place. They can be completely replaced by Annotations, which allow for a very flexible metadata capability. If you have information about a class, and that information never changes, then annotations are a very useful way to represent it.

Can we write marker interface?

Can we create custom marker interface? Of course you can write a marker interface. A marker interface is generally just a Interface with no methods at all (so any class could implement it).

How do I create a marker interface?

We can create our own marker interface, but it has nothing to do with JVM, we can add some checks with instanceOf .

1. Create the empty interface interface Marker{ }
2. Write a class and implements the interface class A implements Marker { //do some task }

Are marker interfaces better than annotations?

It seems annotation is a better choice than the marker interface as the same effect can be achieved by the annotations. It can mark variables, methods, and/or classes. It can mark any class specifically, or via inheritance. A marker interface will mark all subclasses of the marked class.

Why marker interface does not have any methods?

Marker Interfaces in Java have special significance because of the fact that they have no methods declared in them which means that the classes implementing these interfaces don’t have to override any of the methods. A few of the marker interfaces already exist in the JDK like Serializable and Cloneable.

What is marker interface in Java Mcq?

Explanation: A marker interface is an interface with no fields and methods. In other words, an empty interface (contains nothing) is known as the marker interface.

How to create custom marker interface in Java?

– To create your own Java Annotation you must use @interface Annotation_name, this will create a new Java Annotation for you. – The @interface will describe the new annotation type declaration. – After giving a name to your Annotation, you will need to create a block of statements inside which you may declare some variables.

What is Marker interfaces in Java and why required?

– Cloneable interface : Cloneable interface is present in java.lang package. There is a method clone () in Object class. – Serializable interface : Serializable interface is present in java.io package. It is used to make an object eligible for saving its state into a file. – Remote interface : Remote interface is present in java.rmi package.

What does JVM do with marker interface in Java?

– Cloneable Interface. Cleanable interface in Java is also a marker interface that belong to java.lang package. – Serializable Interface. It is a marker interface in Java that is defined in the java.io package. – Remote Interface. Remote interface is a marker interface that belong to java.rmi package.

What is a marker or tagged interface in Java?

– it emphasizes important, high-level aspects of a class, not otherwise expressed in code. – for both human readers and tools, it allows quick identification of classes having specific properties. – the javadoc of the tag interface is a natural home for documenting all the characteristics of items that implement the given interface.