NEET / State Class 12 Board (e.g. ISC) Computer Science Flashcards

24 sample cards from the Computer Science deck

Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.

1. What are the four pillars of Object-Oriented Programming?

   Encapsulation, Inheritance, Polymorphism, and Abstraction.

2. Distinguish between a class and an object.

   A class is a blueprint/template defining attributes and methods; an object is a concrete instance of a class occupying memory.

3. What is the difference between method overloading and method overriding in Java?

   Overloading: same method name with different parameter lists in the same class (compile-time polymorphism). Overriding: subclass redefines a superclass method with the same signature (run-time polymorphism).

4. What does the keyword 'this' refer to in Java?

   It refers to the current object on which the method or constructor is being invoked.

5. What is a constructor and how does it differ from a method?

   A constructor initializes a new object; it has the same name as the class, has no return type, and is called automatically when the object is created.

6. What is the difference between a static variable and an instance variable?

   A static (class) variable is shared by all objects of the class; an instance variable has a separate copy for each object.

7. How do you find the length of an array versus a String in Java?

   For an array use the field array.length; for a String use the method str.length().

8. In Java, are array indices zero-based or one-based, and what is the index range for an array of size n?

   Zero-based; valid indices range from 0 to n-1.

9. What is the difference between String, StringBuffer, and StringBuilder in Java?

   String is immutable; StringBuffer is mutable and thread-safe (synchronized); StringBuilder is mutable but not synchronized (faster, single-threaded).

10. What does the substring(int beginIndex, int endIndex) method return in Java?

    The substring from beginIndex (inclusive) to endIndex (exclusive).

11. What is recursion and what two components must every recursive method have?

    Recursion is a method calling itself. It must have a base case (stopping condition) and a recursive case that progresses toward the base case.

12. What happens if a recursive method has no valid base case?

    It recurses indefinitely, eventually causing a StackOverflowError due to stack memory exhaustion.

13. Write the recurrence for computing factorial(n) recursively.

    factorial(n) = 1 if n = 0 or 1; otherwise factorial(n) = n × factorial(n-1).

14. How does the bubble sort algorithm work?

    It repeatedly steps through the list, comparing adjacent elements and swapping them if out of order, so the largest element 'bubbles' to the end each pass.

15. How does selection sort work?

    It repeatedly finds the minimum element from the unsorted portion and swaps it into its correct position at the front.

16. How does insertion sort work?

    It builds a sorted portion one element at a time by taking the next element and inserting it into its correct position among the already-sorted elements.

17. What is the time complexity of linear search versus binary search?

    Linear search is O(n); binary search is O(log n) but requires a sorted array.

18. What is the worst-case time complexity of bubble, selection, and insertion sort?

    All three are O(n²) in the worst case.

19. What is the difference between an array and a linked list?

    An array stores elements in contiguous memory with fixed size and O(1) random access; a linked list uses nodes with pointers, has dynamic size, and O(n) sequential access.

20. What is Big-O notation used to express?

    The asymptotic upper bound on the growth rate of an algorithm's running time (or space) as input size increases.

21. In Java, what is the purpose of wrapper classes such as Integer and Double?

    They wrap primitive types into objects, enabling use in collections and providing utility methods; e.g. Integer wraps int, Double wraps double.

22. What are autoboxing and unboxing in Java?

    Autoboxing automatically converts a primitive to its wrapper object (int→Integer); unboxing converts a wrapper object back to a primitive (Integer→int).

23. In Java exception handling, what is the difference between 'throw' and 'throws'?

    'throw' is used to explicitly raise an exception object inside code; 'throws' is declared in a method signature to indicate the exceptions a method may propagate.

24. What is the purpose of the 'finally' block in a try-catch statement?

    It contains code that always executes whether or not an exception occurs, typically used for cleanup such as closing files or resources.

What this deck covers

Computer Science flashcards FAQ