Java Interface Test – 1

1. Which of the following is an incorrect statement about packages?

2. What will be the output of the following Java 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);
            }
}

3. What will be the output of the following Java program?

   
    interface calculate
    {
        void cal(int item);
    }
    class displayA implements calculate
    {
        int x;
        public void cal(int item)
        {
            x = item * item;            
        }
    }
    class displayB implements calculate
    {
        int x;
        public void cal(int item)
        {
            x = item / item;            
        }
    }
    class interfaces 
    {
        public static void main(String args[])
        {
            displayA arr1 = new displayA;
            displayB arr2 = new displayB;
            arr1.x = 0;
            arr2.x = 0;      
            arr1.cal(2);
            arr2.cal(2);
            System.out.print(arr1.x + " " + arr2.x);
        }
    }

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

5. Which of these keywords is used to define interfaces in Java?

6. Which of these keywords is used by a class to use an interface defined previously?

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

8. What will be the output of the following Java 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);
        }
    }

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