Deutsche Bank Senior Java Developer Interview Questions and Answers

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
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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 memory Managment
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Q2. Garbage Collection
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Print Dice combination based on the rolled output

Trapping rain water and median of two sorted array

Q1. Oops and dbms questions?
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Q2. Code question in Array and string?
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Q1. Tell me about yourself
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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
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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. Explain event driven architecture of node.js
Ans. 
Node.js uses event-driven architecture where events trigger callbacks to handle asynchronous operations.
• Node.js uses event loop to handle asynchronous operations efficiently

• Events are emitted by various objects in Node.js like HTTP servers, file system, etc.

• Callbacks are registered to handle events and execute code when events occur
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Q1. Explain Encapsulation
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Encapsulation is the concept of bundling data and methods that operate on the data into a single unit.
• Encapsulation helps in hiding the internal state of an object and only exposing necessary functionalities.

• It allows for better control over the data by preventing direct access from outside the class.

• Encapsulation also helps in achieving data abstraction and information hiding.

• Example: In a class representing a car, th...read more
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Q2. How to call rest API
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To call a REST API, you can use tools like Postman or code in languages like JavaScript or Python.
• Use tools like Postman to make HTTP requests to the API endpoints

• In programming languages like JavaScript, use libraries like Axios or Fetch to make API calls

• Include necessary headers, parameters, and authentication tokens in the request

• Handle the response data accordingly, whether it's JSON, XML, or other formats
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