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SARAL SAXENA said...

Javin gr8 article ..!! perfect Expnation..!!

@electronics for u ...yeah we can create our own marker interface...

For example, suppose I declare a new marker interface Foo:

public interface Foo {
}
... and then declare a class Bar that implements Foo:

public class Bar implements Foo {
private final int i;

public Bar(int i) { this.i = i; }
}
I am now able to refer to an instance of Bar through a reference of type Foo:

Foo foo = new Bar(5);
... and also check (at runtime) whether an object implements Foo:

if (o instanceof Foo) {
System.err.println("It's a Foo!");
}
This latter case is typically the driver behind using marker interfaces; the former case offers little benefit as there are no methods that can be called on Foo (without first attempting a downcast)

Apr 13, 2013, 5:46:44 AM

Posted to What is Marker interface in Java and why required? Answer