abstract class questions in java

Objective type questions on abstract class in java and answers


(1)

abstract class Abstract {

    

    public static void main(String[] args){

         System.out.print("It is abstract class");

    }

   

    static{

         System.out.println("Why");

    }

}

What will output when you compile and run the above code?

         

(a) Why

    It is abstract class

(b) It is abstract class

    Why

(c)It is abstract class

(d)Compiler error

Answer: (a)

(2)

abstract class Abstract {

    

    public static void main(String[] args){

         double[] array={1D,2d,3,4.,5.0};

         display(array);

    }

   

    abstract void display();

    static void display(double[] arr){

         for(double d:arr)

         System.out.println(d);

    }

}

What will output when you compile and run the above code?

         

(a) 1.0

    2.0

    3.0

    4.0

    5.0

(b)1.0

(c)5.0

(d)Compiler error

Answer: (a)

 (3)

class Abstract {

    

    public static void main(String[] args){

         float[] array={1F,2f};

         show(array);

    }

   

    abstract void display();

   

    static void show(float[] arr){

         for(int i=0;i<ARR.< span="">length;i++)

         System.out.println(arr[i]);

    }

}

What will output when you compile and run the above code?

         

(a)1.0

   2.0

(b)1.0

(c)1.0

   2.0

   null

(d)Compiler error

Answer: (d)

(4)

abstract class Abstract {

    

    public static void main(String[] args){

         if(new Abstract() instanceof Abstract)

             System.out.print("True");

         else

             System.out.print("False");

        

    }

}

What will output when you compile and run the above code?

         

(a)True

(b)False

(c)Run time exception

(d)Compiler error

Answer: (d)

(5)

abstract class Abstract {

    static int a=3;

    static float b=5.3f;

    Abstract(p,q){

         a=p;

         b=q;

    }

    public static void main(String[] args){

         System.out.print((int)a+~a+b);

        

    }

}

What will output when you compile and run the above code?

         

(a)4.3

(b)4

(c)5

(d)Compiler error

Answer: (d)

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