Java Interface
Java Interface
A Java interface declares methods that classes are expected to implement. It encapsulates a set of associated behaviors that can be used by dissimilar classes. Interfaces contain no instance fields and cannot be instantiated.
A class realizes (implements) an interface by promising to provide the implementation for all of the methods in the interface. An interface can be implemented by many classes and a class can implement multiple interfaces. All methods in an interface are automatically public and abstract.
public interface Flier
{
void fly( );
}
public class Bird implements Flier
{
public void fly( ) // public must be written here
{
System.out.println("Using my wings to fly");
}
}
public class Airplane implements Flier
{
public void fly( )
{
System.out.println("Using my jet engines to fly ");
}
}
