40+ Quess Interview Questions and Answers

The minimum number of weighings necessary is 2.

• Divide the 9 balls into 3 groups of 3.

• Weigh any two groups against each other.

• If the two groups weigh the same, the heavier ball is in the third group.

• If one group is heavier, the heavier ball is in that group.

• Take the heavier group and weigh any two balls against each other.

• If they weigh the same, the heavier ball is the remaining one.

• If one ball is heavier, it is the heavier ball.

Microservices offer advantages such as scalability, flexibility, and easier maintenance.

• Scalability: Microservices allow for individual components to be scaled independently, making it easier to handle high traffic.

• Flexibility: Microservices can be developed and deployed independently, allowing for faster development and deployment cycles.

• Easier maintenance: Microservices are smaller and more focused, making it easier to identify and fix issues.

• Example: Netflix uses microserv...read more

I will ensure that our code is properly protected by implementing security measures and legal actions if necessary.

• Implement security measures such as encryption and access control to prevent unauthorized access to our code.

• Monitor for any suspicious activity and take immediate action if any unauthorized access is detected.

• If necessary, take legal action against the rival company for intellectual property theft.

• Collaborate with legal and management teams to ensure that our co...read more

Program to get the middle of a linked list in a single iteration using two pointers.

• Use two pointers, slow and fast, to traverse the linked list

• Move slow pointer one step at a time and fast pointer two steps at a time

• When fast pointer reaches the end, slow pointer will be at the middle node

Singleton is a design pattern that restricts the instantiation of a class to one object.

• Singleton pattern is used when we need to ensure that only one instance of a class is created and used throughout the application.

• To implement Singleton, we make the constructor private and provide a static method to get the instance of the class.

• Singleton can be broken by using reflection, serialization, and cloning.

• Reflection can be used to access the private constructor and create a new...read more

To switch from one branch to another in git, use the 'git checkout' command.

• Use 'git checkout' followed by the name of the branch you want to switch to.

• Make sure to commit or stash any changes before switching branches.

• Example: 'git checkout new-branch'

Linked list is a linear data structure while tree is a hierarchical data structure.

• Linked list is used when we need to maintain a sequence of elements and perform operations like insertion and deletion at any position.

• Tree is used when we need to represent a hierarchical structure and perform operations like searching, insertion, and deletion efficiently.

• Linked list has a single pointer to the next node while tree has multiple pointers to its child nodes.

• Linked list has a lin...read more

Maven clean removes target directory and install compiles and packages the project

• Maven clean removes the target directory and all the compiled classes and resources

• Maven install compiles and packages the project and installs the resulting artifact into the local repository

• Maven clean and install together ensure that the project is built from scratch and all dependencies are resolved

• Useful when there are changes in the project dependencies or configuration

APIs can be secured using various methods such as authentication, encryption, rate limiting, and input validation.

• Implement authentication using OAuth or JWT

• Use HTTPS encryption to protect data in transit

• Implement rate limiting to prevent DDoS attacks

• Validate input data to prevent injection attacks

• Regularly update and patch software to prevent vulnerabilities

Deadlock is a situation where two or more threads are blocked and waiting for each other to release resources.

• Deadlock occurs when two or more threads are waiting for each other to release resources.

• It can be resolved by using techniques like resource allocation graph, timeout, and prevention.

• Prevention can be done by avoiding circular wait, hold and wait, and no preemption.

• Example: Thread A holds resource X and waits for resource Y, while Thread B holds resource Y and waits ...read more

A Future object represents the result of an asynchronous computation in Java.

• Future objects are used to retrieve the result of an asynchronous computation when it becomes available.

• They provide a way to check if the computation is complete, cancel the computation, and retrieve the result.

• They are commonly used in multithreaded programming and in Java's Executor framework.

• Example: Future future = executor.submit(new Callable() { public Integer call() { return 42; }});

• Example: ...read more

HashMap is a data structure that stores key-value pairs and uses hashing to retrieve values quickly.

• HashMap uses hashing to store and retrieve values quickly

• It uses an array of buckets to store key-value pairs

• The hash code of the key is used to determine the bucket where the key-value pair is stored

• If two keys have the same hash code, they are stored in the same bucket as a linked list

• When retrieving a value, the hash code of the key is used to find the bucket and then the li...read more

Print y sub arrays with x elements from given array and variables.

• Use a loop to iterate through the array and create subarrays of x elements.

• Use another loop to print y number of subarrays.

• Handle edge cases where x or y is greater than the length of the array.

Find the first non-repeating character in a string.

• Create a hash table to store the frequency of each character in the string.

• Iterate through the string and check the frequency of each character.

• Return the first character with a frequency of 1.

Spring filter is an interface used to intercept HTTP requests and responses.

• Spring filter is used to perform tasks such as logging, security, and caching.

• It can be used to modify the request or response before it reaches the controller.

• Examples of Spring filters include CharacterEncodingFilter, CorsFilter, and CsrfFilter.

A convenience annotation that combines @Configuration, @EnableAutoConfiguration, and @ComponentScan.

• Used to bootstrap a Spring Boot application.

• Automatically configures the Spring application based on the dependencies added to the classpath.

• Scans the package and its sub-packages for components and services.

• Example: @SpringBootApplication public class MyApplication { public static void main(String[] args) { SpringApplication.run(MyApplication.class, args); } }

Disadvantages of what? Please specify.

Save() method inserts a new record into the database, while persist() method can also be used to update an existing record.

• save() method is used to insert a new record into the database

• persist() method can also be used to insert a new record, but it can also be used to update an existing record

• save() method returns the generated ID immediately, while persist() method does not

• save() method can be called outside of a transaction, while persist() method must be called within a t...read more

Hibernate manages object lifecycle through three states: transient, persistent, and detached.

• When an object is created, it is in the transient state.

• When the object is saved using session.save() method, it becomes persistent.

• When the session is closed or the object is explicitly detached using session.evict() method, it becomes detached.

• Detached objects can be re-attached to a new session using session.update() or session.merge() methods.

• Objects can also be deleted using sess...read more

Merge overlapping intervals in Java

• Sort the intervals based on their start time

• Iterate through the intervals and merge overlapping ones

• Use a stack to keep track of merged intervals

Stack peek returns the top element without removing it, while stack pop removes and returns the top element.

• Stack peek is used to check the top element of the stack without removing it.

• Stack pop is used to remove and return the top element of the stack.

• Both methods operate on the top element of the stack.

RequestMapping is used for all HTTP methods while PostMapping is specifically for POST requests.

• RequestMapping is a general-purpose annotation for mapping HTTP requests to handler methods.

• PostMapping is a specialized version of RequestMapping that only maps POST requests.

• RequestMapping can be used for GET, POST, PUT, DELETE, and other HTTP methods.

• PostMapping is useful when you want to handle only POST requests and ignore other HTTP methods.

• Example: @RequestMapping(value = "/...read more

RestController is used for RESTful web services while Controller is used for traditional web applications.

• RestController returns data in JSON or XML format while Controller returns data in HTML format.

• RestController uses @RestController annotation while Controller uses @Controller annotation.

• RestController is used for building RESTful web services while Controller is used for building traditional web applications.

• RestController is a specialized version of Controller in Spring...read more

Trees are data structures that store hierarchical data. Binary Search Trees are a type of tree that maintains sorted order.

• Trees are composed of nodes that have a parent-child relationship.

• Binary Search Trees have at most two children per node and the left child is always smaller than the parent while the right child is always larger.

• Binary Search Trees allow for efficient searching, insertion, and deletion operations.

• Examples of Binary Search Trees include AVL Trees and Red-...read more

Remove duplicates from an array of strings

• Create a new empty array

• Loop through the original array and check if the element already exists in the new array

• If not, add it to the new array

• Return the new array

Linked list is dynamic and efficient for insertion/deletion, while ArrayList is faster for random access.

• Linked list uses pointers to connect nodes, while ArrayList uses an underlying array.

• Linked list is better for frequent insertion/deletion, while ArrayList is better for frequent random access.

• Linked list has O(1) time complexity for insertion/deletion, while ArrayList has O(n) time complexity.

• Example: Linked list is used in implementing stacks, queues, and hash tables, wh...read more

A family tree is a real-life example of a tree data structure.

• A family tree has a root node (the oldest ancestor) and branches out to children, grandchildren, etc.

• Each node can have multiple child nodes but only one parent node.

• The tree structure allows for easy visualization of relationships and ancestry.

• Other examples include file systems, organization charts, and decision trees.

Code for insertion in a binary tree

• Create a new node with the given data

• If the tree is empty, make the new node as root

• Else, traverse the tree to find the appropriate position to insert the new node

• If the data is less than the current node, go to the left subtree

• If the data is greater than the current node, go to the right subtree

• Repeat until an appropriate position is found

• Set the new node as the child of the appropriate parent node

Abstract classes are classes that cannot be instantiated and are meant to be extended by other classes.

• Abstract classes are declared using the 'abstract' keyword.

• They can have abstract and non-abstract methods.

• Abstract methods are declared without a body and must be implemented by the subclass.

• Abstract classes can have constructors and instance variables.

• They are useful for creating a common interface for a group of related classes.

A function pointer is a variable that stores the memory address of a function.

• Function pointers allow passing functions as arguments to other functions.

• They can be used to implement callbacks and event handlers.

• Function pointers can be used to implement polymorphism in C.

• Example: int (*funcPtr)(int, int) = &add; where add is a function that takes two integers and returns their sum.

• Function pointers can also be used to create function tables and switch statements.

Scopes of bean refer to the visibility and lifecycle of a bean in a Spring application.

• There are four scopes of bean in Spring: singleton, prototype, request, and session.

• Singleton scope creates only one instance of a bean and is the default scope.

• Prototype scope creates a new instance of a bean every time it is requested.

• Request scope creates a new instance of a bean for each HTTP request.

• Session scope creates a new instance of a bean for each HTTP session.

• Scopes can be defi...read more

Static functions belong to the class and not to the instance of the class.

• Can be called without creating an instance of the class

• Cannot access non-static members of the class

• Can access other static members of the class

• Used for utility functions or helper functions

Use a hashmap to count the occurrences of each character in the string.

• Create a hashmap to store character counts

• Iterate through the string and update counts in the hashmap

• Return the hashmap with character counts

Cells communicate between 2 sites through various signaling pathways, including direct cell-to-cell contact and chemical signaling.

• Cells can communicate through direct cell-to-cell contact, such as gap junctions or cell adhesion molecules.

• Cells can also communicate through chemical signaling, such as paracrine signaling (local signaling) or endocrine signaling (long-distance signaling).

• Examples include neurotransmitters in the nervous system, hormones in the endocrine system,...read more

Copy constructor creates a new object by copying an existing object.

• Used to initialize an object with another object of the same class

• Takes a reference to an object of the same class as a parameter

• Creates a new object with the same values as the parameter object

• Deep copy and shallow copy are two types of copy constructors

Live coding of sorting algorithms and reversing a string and number on an online compiler.

• Use bubble sort, selection sort, or insertion sort for sorting algorithms.

• For reversing a string, use a loop to iterate through the string and swap the characters.

• For reversing a number, convert it to a string, reverse the string, and convert it back to a number.

Quick sort is a divide-and-conquer algorithm that sorts an array by partitioning it into two sub-arrays.

• Choose a pivot element from the array

• Partition the array around the pivot element

• Recursively apply quick sort to the left and right sub-arrays

• Combine the sorted sub-arrays to get the final sorted array

I will use a combination of messaging systems, data replication, and versioning to ensure consistency and availability.

• Use messaging systems like Kafka or RabbitMQ to ensure reliable communication between systems

• Implement data replication to ensure that data is available on multiple nodes

• Use versioning to ensure that all nodes are working with the same data

• Implement conflict resolution strategies to handle conflicts that may arise

• Use distributed locking mechanisms to prevent ...read more

C language is a powerful and efficient programming language commonly used for system programming and embedded systems.

• C language is a procedural programming language

• It is widely used for developing operating systems, compilers, and embedded systems

• C is known for its efficiency and low-level access to memory

• Example: Declaring an array in C - int arr[5];

Reverse a linked list by changing the direction of pointers

• Start with three pointers: current, previous, and next

• Iterate through the linked list, updating pointers to reverse the direction

• Update the head of the linked list to be the last node visited

Backup and recovery for RAC DB instances involves using RMAN for backups and restoring from backups in case of failures.

• Use RMAN for taking backups of RAC DB instances

• Implement a backup strategy that includes full, incremental, and archive log backups

• Test the backups regularly to ensure they can be restored successfully

• In case of failures, restore the database using RMAN backups

Network refers to the interconnection of devices for communication and resource sharing.

• Network is a collection of computers, servers, mainframes, network devices, and other devices connected to one another for sharing data and resources.

• Types of networks include LAN (Local Area Network), WAN (Wide Area Network), WLAN (Wireless Local Area Network), and VPN (Virtual Private Network).

• Network protocols like TCP/IP, HTTP, and FTP govern the communication between devices on a netw...read more