Deutsche Bank 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. 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. How do you balance work and life ?
Ans. 
I prioritize my work and set boundaries to ensure a healthy work-life balance.
• I prioritize my tasks and set realistic goals to manage my workload effectively.

• I establish clear boundaries between work and personal life to avoid burnout.

• I practice time management techniques, such as creating schedules and prioritizing tasks.

• I make sure to take breaks and engage in activities outside of work to recharge.

• I communicate open...read more
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Q2. What is a positive quote for work ?
Ans. 
A positive quote for work can inspire and motivate individuals to achieve their goals and excel in their professional endeavors.
• A positive attitude leads to positive outcomes.

• Hard work and dedication are the keys to success.

• Believe in yourself and your abilities.

• Success is not final, failure is not fatal: It is the courage to continue that counts.

• The only way to do great work is to love what you do.

• Don't watch the cloc...read more
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It was spring boot java based online round

Q1. Optional in java.
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Q2. Eager and lazy initialization in simgleton design pattern
Ans. 
Eager initialization creates the instance of Singleton class at the time of class loading, while lazy initialization creates the instance only when it is required.
• Eager initialization can lead to resource wastage if the instance is never used.

• Lazy initialization is more efficient as it only creates the instance when needed.

• Eager initialization is thread-safe by default, while lazy initialization requires synchronizatio...read more
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Java and sql questions

Q1. Basics of java ans core java
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Q1. Basic mcq's related to Java,spring Boot
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Q1. Importance of Equals and hashcode
Ans. 
Equals and hashcode are important for object comparison and hashing in Java.
• Equals method is used to compare two objects for equality.

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

• Equals and hashcode are used in collections like HashMap and HashSet for efficient retrieval and storage.
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Q2. Difference between comparable and comparator
Ans. 
Comparable is an interface used for natural ordering, while Comparator is an interface used for custom ordering.
• Comparable is implemented by the class itself to define the natural ordering of objects.

• Comparator is implemented by a separate class to define custom ordering of objects.

• Comparable uses the compareTo() method to compare objects, while Comparator uses the compare() method.

• Example: String class implements Comp...read more
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Q3. Write code for Singelton design pattern
Ans. 
Singleton design pattern ensures a class has only one instance and provides a global point of access to it.
• Create a private static instance of the class

• Provide a public static method to access the instance

• Ensure the constructor is private to prevent instantiation
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Q4. Difference b/w hashmap and hashtable
Ans. 
HashMap is non-synchronized and allows null values, while Hashtable is synchronized and does not allow null keys or values.
• HashMap is non-synchronized, while Hashtable is synchronized

• HashMap allows null values, while Hashtable does not allow null keys or values

• HashMap is faster than Hashtable

• HashMap is part of the Java Collections Framework, while Hashtable is a legacy class
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Q1. How do you resolve conflicts within the team
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Q2. What went well in you last company? What didn't go well?
Ans. 
At my last company, effective communication and collaboration among team members went well, but there were challenges with project timelines and resource allocation.
• Effective communication and collaboration among team members

• Challenges with project timelines

• Challenges with resource allocation
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