What is a java marker interface?
FAQ Category: Abstract and Interface.
Abstract and Interface
Difference between a Java interface and a Java abstract class?
Methods of a Java interface are implicitly abstract and cannot have implementations. A Java abstract class can have instance methods that implements a default behavior. Variables declared in a Java interface is by default final. A Java abstract class may contain non-final variables. Memebers of a Java interface are public by default. A Java abstract class can have the usual flavors [...]FAQ Category: Abstract and Interface.
When can an object reference be cast to a Java interface reference?
When a Java object implements the referenced interface it can be cast to the Java interface reference.FAQ Category: Abstract and Interface.
Java interface
A java class containing all the methods as abstract is called an interface. A method that has no implementation and which is expected to be implemented by a subclass is called an abstract method. Java interface can contain constants. When an interface needs to be instantiated it should be implemented by a class and all [...]FAQ Category: Abstract and Interface.
How can you invoke a defined method of an abstract class?
An abstract class cannot be instantiated directly. An abstract class has to be sub-classed first and then instantiated. Only then the method defined in the abstract class can be invoked.FAQ Category: Abstract and Interface.
What is an abstract class?
A class containing atleast one abstract method is called an abstract class. A method that has no implementation and which is expected to be implemented by a subclass is called an abstract method. An Abstract class cannot be instantiated. It is expected to be extended by a subclass. An abstract class may contain static variables [...]FAQ Category: Abstract and Interface.