Interfaces And Abstract Classes MCQ

Test your knowledge with important Interfaces And Abstract Classes MCQ and their applications. These MCQs are beneficial for competitive exams too. Explore 30+ more Interfaces And Abstract Classes MCQs on Bissoy. Bissoy App

• Runnable is a _____ .
  ক

  class

  খ

  abstract class

  গ

  interface

  ঘ

  vaiable

  ঙ

  method
• In Java, declaring a class abstract is useful
  ক

  To prevent developers from further extending the class.

  খ

  When it doesn't make sense to have objects of that class.

  গ

  When default implementations of some methods are not desirable.

  ঘ

  To force developers to extend the class not to use its capabilities.

  ঙ

  When it makes sense to have objects of that class.
• Which of the following is a correct interface?
  ক

  <span class="key">interface</span> <span>A</span> <span class="braces">{</span> <span class="key">void</span> <span>print()</span> <span class="braces">{ } }</span>

  খ

  <span class="key">abstract interface <span>A <span class="braces">{ <span>print(); <span class="braces">}

  গ

  <span class="key">abstract interface</span> <span>A</span> <span class="braces">{</span> <span class="key">abstract void</span> <span>print();</span> <span class="braces">{ }}</span>

  ঘ

  <span class="key">interface</span> <span>A</span> <span class="braces">{</span> <span class="key">void</span> <span>print();</span> <span class="braces">}</span>
• Which of the following statements regarding abstract classes are true?
  ক

  An abstract class can be extended.

  খ

  A subclass of a non-abstract superclass can be abstract.

  গ

  A subclass can override a concrete method in a superclass to declare it abstract.

  ঘ

  An abstract class can be used as a data type.

  ঙ

  All of the above
• Which of the following declares an abstract method in an abstract Java class?
  ক

  public abstract method();

  খ

  public abstract void method();

  গ

  public void abstract Method();

  ঘ

  public void method() {}

  ঙ

  public abstract void method() {}
• Which of the following class definitions defines a legal abstract class?
  ক

  class A { abstract void unfinished() { } }

  খ

  class A { abstract void unfinished(); }

  গ

  abstract class A { abstract void unfinished(); }

  ঘ

  public class abstract A { abstract void unfinished(); }