NatWest Markets Lead Java Developer Interview Questions and Answers

Q1. Difference between hashmap and hash table
Ans. 
HashMap is non-synchronized and allows null values, while HashTable is synchronized and does not allow null values.
• HashMap is non-synchronized, meaning it is not thread-safe, while HashTable is synchronized and thread-safe.

• HashMap allows null values for both keys and values, while HashTable does not allow null keys or values.

• HashMap is generally preferred for non-thread-safe applications, while HashTable is used in mul
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Q2. Significance of equals and hashcode in java
Ans. 
Equals method is used to compare the content of objects while hashcode method is used to generate a unique integer value for an object.
• Equals method is used to compare the content of objects for equality.

• Hashcode method is used to generate a unique integer value for an object.

• Both methods are important for implementing proper object comparison and hashing in Java.
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Q1. What motivates you to come to office
Ans. 
I am motivated to come to the office by the opportunity to work on challenging projects, collaborate with talented colleagues, and contribute to the success of the team.
• Challenging projects provide a sense of accomplishment and growth

• Collaborating with talented colleagues allows for learning and innovation

• Contributing to the success of the team fosters a sense of purpose and fulfillment
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Q2. Any scenario where you coached and mentored your collegue in previous organisation?
Ans. 
Yes, I coached a junior developer on implementing design patterns in a project.
• Provided guidance on how to apply design patterns in code

• Reviewed their code and provided feedback for improvement

• Encouraged them to ask questions and seek clarification
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Q1. Mental trauma and frustrated scenarios Even after solving 3 Link list coding problem and 20+ technical questions, and then following up about 20 times, and even after calls and emails, there has been no...read more
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Q2. Even after solving 3 coding problem and 20+ technical questions, and then following up about 20 times, and even after calls and emails, there has been no response. Would it be appropriate for me to post ...read more
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Q1. Questions on apache kafka, microservices scenario based queries
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Q2. SQL queries on group by statement
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Q1. Design immutable class
Ans. 
Immutable class is a class whose state cannot be modified after creation.
• Make all fields private and final

• Do not provide setter methods

• Ensure that any mutable objects within the class are also immutable
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Q2. Difference between lock and sync
Ans. 
Lock and sync are both mechanisms used in Java for thread synchronization, but they have different implementations and use cases.
• Lock is a low-level synchronization mechanism provided by the java.util.concurrent.locks package, while sync (synchronized keyword) is a high-level synchronization mechanism provided by Java.

• Lock provides more flexibility and control over synchronization compared to sync.

• Lock can be used to c...read more
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Q1. Java 8 Features
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Q2. Default Interface
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Q3. Write code for Builder/Factory Pattern, basically anything other than Singleton
Ans. 
Builder/Factory Pattern is used to create objects with complex initialization logic.
• Builder Pattern separates the construction of a complex object from its representation.

• Factory Pattern creates objects without specifying the exact class of object that will be created.

• Builder Pattern is often used to create immutable objects with many optional parameters.

• Factory Pattern is used when there is a need to create multiple i...read more
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Q4. Why is Redux used in React
Ans. 
Redux is used in React to manage the application state in a predictable way.
• Centralized state management for React applications

• Predictable state changes with actions and reducers

• Easier debugging and testing of state changes

• Facilitates communication between components
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Q5. Second Highest Salary from Employee Table
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Q6. Filter a List using Streams

Ans. 

Filter a List using Streams in Java

• Use the filter() method to apply a predicate to each element in the stream

• Use collect() method to convert the stream back to a List

• Example: List names = Arrays.asList("Alice", "Bob", "Charlie"); List filteredNames = names.stream().filter(name -> name.startsWith("A")).collect(Collectors.toList());

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