10+ Amines & Plasticizers Interview Questions and Answers

Program to print even and odd numbers from 1 to 20 using 2 threads alternately.

• Create two threads, one for printing even numbers and one for printing odd numbers.

• Use wait(), notify(), and notifyAll() to ensure alternate printing.

• Ensure synchronization between the two threads to avoid race conditions.

• Example: Thread 1 prints even numbers (2, 4, 6, ...) and Thread 2 prints odd numbers (1, 3, 5, ...).

Default methods in Java 8 allow interfaces to have method implementations, enabling backward compatibility and reducing code duplication.

• Default methods were introduced in Java 8 to provide a way to add new methods to interfaces without breaking existing implementations.

• They allow interfaces to have method implementations, which was not possible before Java 8.

• Default methods can be overridden in implementing classes to provide specific implementations.

• They help in reducing co...read more

Microservices communicate with each other through APIs, messaging queues, or service meshes.

• APIs: Microservices can communicate with each other by exposing APIs that allow them to send and receive data.

• Messaging queues: Microservices can use messaging queues like RabbitMQ or Kafka to send messages to each other asynchronously.

• Service meshes: Microservices can communicate through a service mesh like Istio, which handles communication, security, and monitoring between services.

Using streams in Java 8 to filter and map a list of numbers

• Create a list of numbers

• Use stream to filter out even numbers

• Use map to square each number

• Collect the results into a new list

The project involves creating a web-based platform for online shopping with features like user registration, product browsing, shopping cart, and payment processing.

• User registers on the platform with personal information

• User browses products by category or search

• User adds products to the shopping cart

• User proceeds to checkout and makes payment

• Order is confirmed and user receives a confirmation email

Annotation used to mark a class as a Spring Boot application

• Combines @Configuration, @EnableAutoConfiguration, and @ComponentScan annotations

• Used to bootstrap and launch a Spring application

• Automatically scans for Spring components in the package and sub-packages

Microservices are a software development technique where an application is composed of small, independent services that communicate with each other.

• Microservices are designed to be small, focused on specific tasks, and independently deployable.

• Each microservice typically runs its own process and communicates with other services through APIs.

• Microservices allow for easier scalability, flexibility, and maintenance compared to monolithic architectures.

• Examples of companies using...read more

Custom recyclerview with appropriate data structures

• Create a custom adapter extending RecyclerView.Adapter

• Implement onCreateViewHolder() and onBindViewHolder() methods

• Use appropriate data structures like ArrayList or HashMap for efficient data handling

• Implement onClickListener for item clicks

• Use ViewHolder pattern for efficient view recycling

Strings are immutable to ensure data integrity and security.

• Immutable strings prevent accidental changes to data

• Immutable strings allow for safe sharing of data between different parts of a program

• Immutable strings help prevent security vulnerabilities like SQL injection attacks

Checked exceptions are exceptions that must be either caught or declared in the method signature.

• Checked exceptions are subclasses of Exception (excluding RuntimeException and its subclasses)

• Checked exceptions must be either caught using try-catch block or declared in the method signature using 'throws' keyword

• Examples of checked exceptions in Java include IOException, SQLException, and ClassNotFoundException

Static is used to define class-level variables and methods, while final is used to define constants that cannot be changed.

• Static variables belong to the class itself, while final variables are constants that cannot be modified.

• Static methods can be called without creating an instance of the class, while final methods cannot be overridden.

• Static variables are shared among all instances of a class, while final variables have the same value for all instances.

• Example: 'static in...read more

Java8 introduced several new features including lambda expressions, functional interfaces, streams, and default methods.

• Lambda expressions allow you to write code in a more concise and readable way.

• Functional interfaces are interfaces with a single abstract method, which can be implemented using lambda expressions.

• Streams provide a way to work with collections of objects in a functional style.

• Default methods allow interfaces to have methods with implementations.

• Other features...read more

ArrayList is better for random access, LinkedList is better for frequent insertions/deletions.

• ArrayList uses dynamic array to store elements, LinkedList uses doubly linked list.

• ArrayList provides fast random access to elements using index, LinkedList provides fast insertion/deletion at any position.

• Example: ArrayList is suitable for scenarios where random access is required like searching, LinkedList is suitable for scenarios where frequent insertions/deletions are needed lik...read more

Using Java8 streams to solve a problem

• Use stream() method to convert a collection into a stream

• Use filter() method to filter elements based on a condition

• Use map() method to transform elements

• Use collect() method to collect the elements into a new collection

Design and optimize a hashmap

• Choose a good hash function to minimize collisions

• Implement dynamic resizing to handle increasing load factor

• Consider using open addressing or separate chaining for collision resolution

• Use an efficient data structure for storing key-value pairs, such as an array or linked list

Annotation used in Spring to specify which bean to autowire

• Used to disambiguate when multiple beans of the same type are present

• Can be used with @Autowired to specify which bean to inject

• Helps in resolving dependencies when multiple beans of the same type are available

Reverse a linked list by changing the next pointers of each node

• Iterate through the linked list and change the next pointers to reverse the list

• Use three pointers - prev, current, and next to keep track of nodes

• Example: 1 -> 2 -> 3 -> 4 -> null, after reversing: 4 -> 3 -> 2 -> 1 -> null