- Can we declare interface as final?
- Why it is called compile time polymorphism?
- Is interface a polymorphism?
- What makes an interface important when discussing polymorphism?
- What is polymorphism and give an example for the same?
- Can you instantiate an interface?
- How do you explain polymorphism?
- What is difference between class and interface?
- Can abstract class have constructor?
- Where do we use abstract class and interface?
- What is the main difference between an abstract class and an interface?
Can we declare interface as final?
An interface is a pure abstract class.
Hence, all methods in an interface are abtract , and must be implemented in the child classes.
So, by extension, none of them can be declared as final .
Why Interface methods cannot be “static” & “final”?.
Why it is called compile time polymorphism?
Method overloading is one of the way java supports static polymorphism. Here we have two definitions of the same method add() which add method would be called is determined by the parameter list at the compile time. That is the reason this is also known as compile time polymorphism.
Is interface a polymorphism?
Java interfaces are a way to achieve polymorphism. Polymorphism is a concept that takes some practice and thought to master. Basically, polymorphism means that an instance of an class (an object) can be used as if it were of different types. Here, a type means either a class or an interface.
What makes an interface important when discussing polymorphism?
Interfaces allow us to define polymorphism in a declarative way, unrelated to implementation. Two elements are polymorphic with respect to a set of behaviors if they realize the same interfaces.
What is polymorphism and give an example for the same?
The word polymorphism means having many forms. In simple words, we can define polymorphism as the ability of a message to be displayed in more than one form. Real life example of polymorphism: A person at the same time can have different characteristic. Like a man at the same time is a father, a husband, an employee.
Can you instantiate an interface?
An interface can’t be instantiated directly. Its members are implemented by any class or struct that implements the interface. A class or struct can implement multiple interfaces. A class can inherit a base class and also implement one or more interfaces.
How do you explain polymorphism?
Polymorphism is the ability of an object to take on many forms. Any Java object that can pass more than one IS-A test is considered to be polymorphic— tutorialspoint. This means any child class object can take any form of a class in its parent hierarchy and of course itself as well.
What is difference between class and interface?
A class describes the attributes and behaviors of an object. An interface contains behaviors that a class implements. A class may contain abstract methods, concrete methods. An interface contains only abstract methods.
Can abstract class have constructor?
Yes! Abstract classes can have constructors! Yes, when we define a class to be an Abstract Class it cannot be instantiated but that does not mean an Abstract class cannot have a constructor. Each abstract class must have a concrete subclass which will implement the abstract methods of that abstract class.
Where do we use abstract class and interface?
Abstract classes should be used primarily for objects that are closely related, whereas interfaces are best suited for providing a common functionality to unrelated classes. Interfaces are a good choice when we think that the API will not change for a while.
What is the main difference between an abstract class and an interface?
Main difference is 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. An abstract class may contain non-final variables.