10+ J.v.m Public School Interview Questions and Answers

Multiple inheritance is not allowed in Java to avoid the diamond problem.

• Java supports multiple interface inheritance to achieve the same functionality.

• Diamond problem occurs when a class inherits from two classes with a common method.

• Java prioritizes single inheritance to maintain simplicity and avoid ambiguity.

Code to generate a random number between 15-25

• Use Math.random() to generate a random number between 0-1

• Multiply the result with the range (25-15) and add the minimum value (15)

• Use Math.floor() to round down the result to an integer

Oops concepts are fundamental to object-oriented programming. They help in creating modular and reusable code.

• Encapsulation - hiding implementation details of an object from the outside world

• Inheritance - creating new classes from existing ones, inheriting their properties and methods

• Polymorphism - ability of objects to take on many forms, depending on the context

• Abstraction - focusing on essential features of an object, ignoring the rest

Java collections are classes and interfaces that provide a way to store and manipulate groups of objects.

• Java collections include List, Set, Map, Queue, and their respective implementations

• They provide methods for adding, removing, and accessing elements

• Examples include ArrayList, HashSet, TreeMap, and PriorityQueue

Arrays are fixed in size while ArrayLists can dynamically grow and shrink.

• Arrays are of fixed size while ArrayLists can be resized dynamically.

• Arrays can hold primitive data types and objects while ArrayLists can only hold objects.

• Arrays are faster for accessing elements while ArrayLists are faster for adding and removing elements.

• Arrays use square brackets [] to declare while ArrayLists use angle brackets <>.

• Example: String[] names = new String[5]; ArrayList namesList = new ...read more

DSA stands for Data Structures and Algorithms, essential concepts in computer science for efficient problem-solving.

• DSA involves organizing and storing data in a way that allows for efficient retrieval and manipulation.

• Algorithms are step-by-step procedures for solving problems, often involving data structures.

• Understanding DSA is crucial for writing efficient code and solving complex problems in software development.

• Examples of data structures include arrays, linked lists, t...read more

Time theta is a measure of the worst-case time complexity of an algorithm.

• It is used to analyze the performance of algorithms.

• It represents the maximum amount of time an algorithm takes to complete.

• It is denoted by the symbol Θ(n).

Bubble sorting is a simple sorting algorithm that repeatedly steps through the list, compares adjacent elements and swaps them if they are in the wrong order.

• Bubble sort is a comparison-based algorithm

• It works by comparing each pair of adjacent elements and swapping them if they are in the wrong order

• The algorithm repeats this process until no more swaps are needed

• It has a worst-case and average-case complexity of O(n^2)

• Example: [5, 3, 8, 4, 2] -> [3, 5, 4, 2, 8] -> [3, 4, 2,...read more

Elevator system moves people or goods between floors in a building using a motorized platform.

• Elevator car is connected to a system of cables and pulleys controlled by a motor.

• Users select desired floor using buttons inside the elevator or outside on each floor.

• Elevator system uses sensors to detect when doors can open or close safely.

• Emergency brakes engage if there is a malfunction or power outage.

• Modern elevators may use computerized systems for efficient operation.

• Example...read more