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Is the purpose of an interface to hide information?

Anonymous User240312-Jun-2013

Given that interfaces are also used to help hide information, giving the user only a subset of the possible methods they are allowed to use, and, let's say, I have a Person class and interface IPerson.

Now in main, I'm allowed to do

IPerson testy =newPerson();

or

Person testy =newPerson();

So really I'm not restricted from using Person still. So how does the

interface truly hide data?

oopsoops 
Updated on 04-Jul-2023
Anonymous User

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2 Answers

Aryan Kumar

Aryan Kumar

04-Jul-2023

No, the purpose of an interface is not to hide information. The purpose of an interface is to specify a contract between different classes. This contract defines the methods that a class must implement in order to be considered an implementation of the interface.

An interface can be used to hide information in some cases. For example, if an interface defines a method with no implementation, then the implementation of that method can be hidden from classes that implement the interface. However, this is not the primary purpose of an interface.

The primary purpose of an interface is to promote polymorphism. Polymorphism is the ability to use a variable of one type to refer to an object of another type. This can be useful for making code more flexible and reusable.

Here is an example of how an interface can be used to promote polymorphism:

Java

interface IPrintable {
    void Print();
}

class Book implements IPrintable {
    public void Print() {
        System.out.println("This is a book");
    }
}

class Article implements IPrintable {
    public void Print() {
        System.out.println("This is an article");
    }
}

public class Main {

    public static void main(String[] args) {
        IPrintable printable = new Book();
        printable.Print();

        printable = new Article();
        printable.Print();
    }
}

This code will first create an object of the Book class and assign it to a variable of type IPrintable. Then, it will call the Print() method on the variable. The Print() method will be called on the object of the Book class, and the text "This is a book" will be printed to the console.

Next, the code will create an object of the Article class and assign it to the variable of type IPrintable. Then, it will call the Print() method on the variable. The Print() method will be called on the object of the Article class, and the text "This is an article" will be printed to the console.

As you can see, the IPrintable interface allows us to use a variable of type IPrintable to refer to objects of different types. This is polymorphism in action.

Vijay Shukla

Vijay Shukla

12-Jun-2013

Hey Jacob Rasel!

What if You dont have that Person class.


 Object obj = loadObject();
 
 if(obj is IPerson) {
 
  IPerson person = (IPerson) obj;
 
 }


or

  IPerson person = loadPerson();

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