Java Programming Multiple Choice Questions - Interfaces

This section focuses on the "Interfaces" in Java programming. These Multiple Choice Questions (MCQ) should be practiced to improve the Java programming skills required for various interviews (campus interviews, walk-in interviews, company interviews), placements and other competitive examinations.

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

A. interface
B. Interface
C. intf
D. Intf

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2. A java interface can contain _______.

A. Abstract methods(unimplemented) and implemented methods both
B. public Abstract methods
C. public static Final Variables only
D. public static Final Variables and abstract methods both

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

A. Public
B. private
C. Protected
D. All of the mentioned

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4. Which of the following is a correct interface?

A. abstract interface A { abstract void print(); { }}
B. abstract interface A { print(); }
C. interface A { void print() { } }
D. interface A { void print(); }

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5. Which of the following classes directly implement Set interface?

A. Vector
B. HashSet
C. HashTable
D. LinkedList

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

A. Objects
B. Packages
C. Interfaces
D. None of the Mentioned

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7. What is the output of this program?

interface calculate
{
   void cal(int item);
}
class display implements calculate
{
	int x;
	public void cal(int item)
	{
		x = item * item;
	}
}
class Main
{
   public static void main(String args[])
   {
    display arr = new display();
    arr.x = 0;
    arr.cal(2);
    System.out.print(arr.x);
   }
}

A. 0
B. 2
C. 4
D. None of the mentioned

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8. All methods must be implemented of an interface.

A. TRUE
B. FALSE
C. Can be true or false
D. can not say

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9. What type of variable can be defined in an interface?

A. public static
B. private final
C. public final
D. static final

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10. What does an interface contain?

A. Method definition
B. Method declaration
C. Method declaration and definition
D. Method name

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