Amazon Development Centre India Software Engineer Trainee Interview Questions and Answers

Q1. Explain the difference between ArrayList and LinkedList in Java. When would you choose one over the other?
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Q2. What are the advantages and disadvantages of using Java’s synchronized keyword for thread synchronization? Can you explain how the ReentrantLock compares to synchronized?
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Q3. What is the difference between == and .equals() in Java? When should each be used, and what issues can arise from improper usage?
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Q4. How does the Java garbage collector work? Can you describe the different types of garbage collection algorithms available in Java?
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Q5. What are the main features of Java 8? Can you explain how lambdas and the Stream API have changed the way Java applications are written?
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Q6. Describe the differences between checked and unchecked exceptions in Java. Provide examples and explain how to handle them properly.
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Q7. What is the Java Memory Model, and how does it affect multithreading and synchronization? How does volatile help ensure memory visibility?
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Q8. Can you explain the difference between method overloading and method overriding in Java? Provide examples where each should be used.
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Q9. What are functional interfaces in Java? How do they work with lambda expressions? Provide an example of a custom functional interface.
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Q10. What is a Java Stream, and how does it differ from an Iterator? Explain how Streams can be used to process collections efficiently.
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Q11. Explain the concept of immutability in Java. How does the String class achieve immutability, and what are the advantages of immutable objects?
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Q12. What is the difference between final, finally, and finalize in Java? Provide examples to illustrate their usage.
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Q13. Explain the Singleton design pattern in Java. How can you implement it safely to ensure thread safety?
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Q14. What are Java annotations, and how are they used in frameworks like Spring? Explain the difference between built-in and custom annotations.
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Q15. How do Java Streams handle parallel processing? What are the potential pitfalls of using parallel streams, and how can they be mitigated?
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Q16. Explain the difference between ArrayList and LinkedList in Java. ArrayList is implemented as a dynamic array, while LinkedList is a doubly linked list. ArrayList provides fast random access (O(1) complexi...read more
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Q17. What are the advantages and disadvantages of using Java’s synchronized keyword for thread synchronization? The synchronized keyword ensures that only one thread can access a block of code at a time. It pr...read more
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Q18. What is the difference between == and .equals() in Java? == checks for reference equality, meaning it compares memory addresses. equals() checks for value equality, which can be overridden in user-defined...read more
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Q19. How does the Java garbage collector work? Garbage collection in Java automatically reclaims memory occupied by unused objects. The JVM has different types of GC algorithms, including Serial, Parallel, CMS...read more
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Q20. What are the main features of Java 8? Java 8 introduced lambda expressions, enabling functional-style programming. The Stream API allows efficient data processing with map, filter, and reduce operations. ...read more
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Basic aptitude questions to

Basic coding questions

Q1. Thanks tougfh roubd was there
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Q2. What type of round was conducted during the interview?
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Q1. DSA question with Some Stack
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Q2. Discussion around Current project
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Q1. Managerial discussion around resume and some basic java and spring question
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Q2. Java and spring boot question
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Q1. MC question on desing pattern
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Q2. Graph question, tree and hash
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Q3. Design Book my show
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Dp question of jump game

Basic questions only.

Q1. Basic questions like, how react works?
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Q2. What is the equivalent of ReactDOM in mobile application development?
Ans. 
The equivalent of ReactDOM in mobile application development is React Native.
• React Native is a framework for building mobile applications using React.

• It allows developers to write code in JavaScript and render native components.

• Just like ReactDOM in web development, React Native handles rendering components to the screen.
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Q1. What is Closure
Ans. 
Closure is a function that captures the environment in which it was created, allowing it to access variables from that environment even after the function has finished executing.
• Closure allows a function to access variables from its outer scope even after the function has finished executing.

• It is created when a function is defined within another function and the inner function references variables from the outer functi...read more
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Q2. Flat nested array
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Q1. Machine coding questions
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Q2. Das based questions
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Q1. Simple questions
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Q2. Simple questions one on one
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Prime number, Convert given number into hours format with a challengeToken to validate and return the string

Q1. OOPs Inheritance
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Q2. OOPS Polymorphism
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Q1. Sum of n using recursion
Ans. 
Recursively calculate the sum of n numbers
• Define a base case for when n is 0 or 1

• Recursively call the function with n-1 and add n to the result

• Return the result
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Q2. Practical application of dsa in projects
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Data Structures and Algorithms (DSA) are used in projects for efficient data storage, retrieval, and manipulation.
• Optimizing search and sorting algorithms for faster performance

• Implementing data structures like arrays, linked lists, trees, and graphs for organizing data

• Using DSA to solve complex problems like pathfinding, data compression, and cryptography
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Q1. General DSA question leetcode style
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Q1. Discussion on previous project
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