MCQ Single Best Answer Moderate

Q
[Inheritance]

Assume that class Check implements interfaces A and B. How many times will the method abc() be defined in class Check?

interface A
{
    final static int x = 5;

    abstract void abc();
}

interface B
{
    final static int y = 5;

    abstract void abc();
}

    

ID: #24950 Competency focused Practice Questions ISC Class XII Computer Science 5 views
Question Info
#24950Q ID
ModerateDifficulty
Competency focused Practice Questions ISC Class XII Computer ScienceTopic

Choose the Best Option

Click any option to instantly check if you're correct.

  • A Twice
  • B Once
  • C Compile time error
  • D Runtime error
Correct Answer: Option B

Explanation

[Inheritance]

Assume that class Check implements interfaces A and B. How many times will the method abc() be defined in class Check?
interface A { final static int x = 5; abstract void abc(); } interface B { final static int y = 5; abstract void abc(); }
(a) Twice
(b) Once
(c) Compile time error
(d) Runtime error
Correct Answer: (b) Once

Understanding Interfaces:

Both interfaces A and B contain the same abstract method:

void abc();

When a class implements multiple interfaces containing identical method declarations, Java requires only one implementation of that method.

Example:

class Check implements A, B { public void abc() { System.out.println("Method implemented"); } }

Why Only One Definition?

  • Interface methods are abstract by default.
  • Both interfaces declare exactly the same method signature:
    void abc();
  • A single method implementation satisfies both interfaces.

Important Concept:

If multiple interfaces contain identical abstract methods, only one implementation is needed in the implementing class.

Why Other Options are Incorrect?

Option Reason
Twice Incorrect because identical methods from interfaces can be implemented using a single method.
Compile time error No compile-time error occurs because method signatures are same.
Runtime error No runtime error occurs if method is properly implemented.

Conclusion:

The method abc() will be implemented only once in class Check.

Correct Answer: (b) Once

Share This Question

Challenge a friend or share with your study group.