10+ One Stop Solutions Interview Questions and Answers

Complex primary keys in Spring Data JPA can be created using @EmbeddedId or @IdClass annotations

• Use @EmbeddedId annotation to create a composite primary key using an embeddable class

• Use @IdClass annotation to create a composite primary key using a separate class for the key fields

• Implement equals() and hashCode() methods in the embeddable or separate key class for proper comparison and hashing

Given a matrix, replace rows and columns with 0 when encountering a 0.

• Iterate through the matrix and store the row and column indices of 0s in separate sets.

• Iterate through the sets and update the corresponding rows and columns to 0.

To make an object immutable, use final keyword for fields and provide only getters. To make a collection immutable, use Collections.unmodifiableList() or similar methods.

• Use final keyword for fields in the object to prevent them from being modified

• Provide only getters for the fields to ensure they cannot be changed externally

• For collections within the object, use Collections.unmodifiableList() or similar methods to create an immutable view of the collection

Kafka is a distributed streaming platform that allows for the flow of messages through topics, partitions, and consumers.

• Kafka is a distributed streaming platform that allows producers to publish messages to topics.

• Topics are divided into partitions, which allow for parallel processing and scalability.

• Producers can specify a key for a message, which determines the partition to which the message will be sent.

• Consumers can subscribe to one or more partitions within a topic to r...read more

Output list of palindrome strings from a given string.

• Iterate through each substring in the given string and check if it is a palindrome.

• Use two pointers approach to check if a substring is a palindrome.

• Store palindrome substrings in an array and return the array.

Check specific characters in a string using regex match

• Use regex pattern to match specific characters in the string

• For example, to check for digits in a string: /[0-9]/

• Use regex.test() method to check if the pattern exists in the string

I have experience in modernizing legacy applications and platforms.

• I have worked on migrating monolithic applications to microservices architecture.

• I have experience in refactoring code to make it more modular and maintainable.

• I have worked on upgrading outdated technologies to newer versions.

• I have experience in containerization using Docker and Kubernetes.

• I have worked on cloud migration projects, moving applications to AWS and Azure.

Unsubscribe in Angular is used to clean up resources and prevent memory leaks. ngOnDestroy is a lifecycle hook that is called when a component is destroyed.

• Unsubscribe is used to prevent memory leaks by unsubscribing from observables when a component is destroyed.

• onDestroy is a lifecycle hook in Angular that is called when a component is destroyed, allowing for cleanup tasks to be performed.

• Practical benefit of using onDestroy is to release resources, such as unsubscribing fr...read more

Hoisting, closure, and event loop are key concepts in JavaScript.

• Hoisting is the JavaScript behavior where variable and function declarations are moved to the top of their containing scope.

• Closure is the combination of a function bundled together with references to its surrounding state (lexical environment).

• Event loop is a mechanism that allows JavaScript to perform non-blocking operations by offloading tasks to the browser's APIs and queuing them in a loop.

Solid design principles are a set of guidelines for writing maintainable and scalable code.

• Single Responsibility Principle - each class should have only one responsibility

• Open/Closed Principle - classes should be open for extension but closed for modification

• Liskov Substitution Principle - derived classes should be substitutable for their base classes

• Interface Segregation Principle - clients should not be forced to depend on interfaces they do not use

• Dependency Inversion Prin...read more

A trigger is a database object that automatically executes in response to certain events.

• Triggers can be used to enforce business rules or data integrity.

• They can be defined to execute before or after a data modification operation.

• Triggers can be created using SQL statements.

• Examples of events that can trigger a trigger include INSERT, UPDATE, and DELETE operations.

Find duplicate element from array of strings

• Iterate through the array and store each element in a HashSet

• If an element is already in the HashSet, it is a duplicate

To delete an element from a linked list, update the pointers of the previous node to skip the node to be deleted.

• Traverse the linked list to find the node to be deleted

• Update the 'next' pointer of the previous node to skip the node to be deleted

• Free the memory allocated to the node to be deleted

403 status code means forbidden access to the requested resource.

• 403 status code indicates that the server understood the request but refuses to authorize it.

• It is commonly used when the user does not have the necessary permissions to access the resource.

• Examples include trying to access a restricted page without proper credentials or attempting to perform an action that requires higher privileges.

SOLID is a set of five design principles to make software designs more understandable, flexible, and maintainable.

• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Software entities should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Objects of a superclass should be replaceable with objects of its subclasses without affecting the program's correctness.

• I - Interface Segregation...read more

finally is used in exception handling to define a block of code that will always be executed, while finalize is a method in Java used for cleanup operations before an object is destroyed.

• finally is used in try-catch blocks to define a block of code that will always be executed, regardless of whether an exception is thrown or not

• finalize is a method in Java that is called by the garbage collector before an object is destroyed

• Example: try { // code that may throw an exception }...read more