JAVA

Which of these access specifiers can be used for an interface?

• Public  

  
  

• Protected 

  
  

• Private 

  
  

• All of the above

  
  

Which of these can be used to fully abstract a class from its implementation?

• Object;

  
  

• Interfaces;

  
  

• None of the above;

  
  

• packages

Which of the following is the correct way of implementing an interface salary by class manager? 

• class manager extends salary{}

  
  

• class manager implements salary{}

  
  

• class manager imports salary {}

  
  

• none of the mentioned 

Which of the following is an incorrect statement about packages?

• Interfaces specifies what class must do but not how it does

  
  

•  Interfaces are specified public if they are to be accessed by any code in the program

  
  

• All variables in interface are implicitly final and static

  
  

• All variables are static and methods are public if interface is defined public

  
  

What will be the output of the following program?

  interface calculate

    {

        void cal(int item);

    }

    class display implements calculate

    {

        int x;

        public void cal(int item)

        {

            x = item * item;            

        }

    }

    class interfaces

    {

        public static void main(String args[])

        {

            display arr = new display;

            arr.x = 0;      

            arr.cal(2);

            System.out.print(arr.x);

        }

    }

• 0

• 2

• 4

• none

What will be the output of the following program?

interface calculate 

{

            int VAR = 0;

            void cal(int item);

}

        class display implements calculate 

        {

            int x;

          public  void cal(int item)

          {

                if (item<2)

                    x = VAR;

                else

                    x = item * item;            

            }

        }

 class interfaces 

{

            public static void main(String args[]) 

            {

                display[] arr=new display[3];

               for(int i=0;i<3;i++)

               arr[i]=new display();

               arr[0].cal(0);    

               arr[1].cal(1);

               arr[2].cal(2);

               System.out.print(arr[0].x+" " + arr[1].x + " " + arr[2].x);

            }

}

• 0 1 2

  
  

• 0 2 4

  
  

• 0 0 4

  
  

• 0 1 4

  
  

Which of the following Java built-in interfaces is a functional interface?

• Serializable

  
  

  
  

• Comparable

  
  

  
  

• Runnable

  
  

• Cloneable

  
  

Which of the following interfaces does Java provide for manipulating key-value pairs?

• List

  
  

• collection

  
  

• set

• Map

An interface with no methods is known as?

• Abstract Interface

• Marker Interface

• Empty Interface

• Functional Interface

Which of these can be contained in an interface?

• Abstract methods

  
  

•  Constants

  
  

• Default and static methods

  
  

• All of the above