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IN java collections we have both interfaces and classes.
instead of using interfaces why we can't use classes only
like that why we can't use interfaces only. why we need two
things interface and class.
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Answer / vanaja
Java doesn't support multiple inheritance.We achieve
multiple inheritance using interface concept.A class can
have only one super class and number of interface.And more
over interface has only abstract methods. We need a sub
class to implement it.We cannot create an object for an
interface. So we cannot use only the classes or only the
interfaces in java.
| Is This Answer Correct ? | 19 Yes | 1 No |
Answer / reddy
The purpose of interface is to have abstract methods and
the class which implemnts the interface has to define the
methods in the interface.
The reason why java collections have both interfaces and
classes is interface will have common methods which will be
needed by one or many classes. The classes which wants to
behave like this interface will implement this interface
and define methods in the interface.
| Is This Answer Correct ? | 14 Yes | 4 No |
Answer / easwar
Java doesn't support multiple inheritance.We achieve
multiple inheritance using interface concept.A class can
have only one super class and number of interface.And more
over interface has only abstract methods. We need a sub
class to implement it.We cannot create an object for an
interface. So we cannot use only the classes or only the
interfaces in java.
| Is This Answer Correct ? | 0 Yes | 0 No |
Answer / sarath
Both of them have different purpose.
A Class have state(Fields) and behaviour(Methods). But in Interface we are telling a common behaviour.
for example I have a class called ABCBycycle.java . It implements some common behaviour of bycyle from Bycycle interface,
by implementing the Bycycle interface we are telling that ABCBycycle.java have some common behaviour of bycyle.
So iterface not the blue print of state and behaviour.
But Class is the blue print of some state and behaviour
| Is This Answer Correct ? | 0 Yes | 0 No |
Answer / shaik baji
Interface in the sence a generic templet that means it will
define a generic functionalities of a group.
For Ex:- We can say "Car" as an interface
1)let's asume if you want a List interface functionalities
the your class should implements the List interface, that
means you should implement all the methods which are
available in List interface even you are not using all the
methods so that the Java developers designed the classes
which are implements the java.util interfaces.
Now if you want any interface functionalities then you just
create an object of that related java.utill package class
and call the methods by using the object.
2)Java doesn't support multiple inheritance.We achieve
multiple inheritance using interface concept.A class can
have only one super class and number of interface.
| Is This Answer Correct ? | 3 Yes | 4 No |
11. static class A { 12. void process() throws Exception { throw new Exception(); } 13. } 14. static class B extends A { 15. void process() { System.out.println(”B”); } 16. } 17. public static void main(String[] args) { 18. new B().process(); 19. } What is the result? 1 B 2 The code runs with no output. 3 Compilation fails because of an error in line 12. 4 Compilation fails because of an error in line 15.
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