Deloitte Java Developer Interview Questions, Process, and Tips

HashMap is a data structure in Java that stores key-value pairs and allows fast retrieval of values based on keys.

• HashMap implements the Map interface in Java

• It allows null keys and values

• Keys in a HashMap must be unique

• Example: HashMap map = new HashMap<>()

HashMap is a data structure that stores key-value pairs and uses hashing to efficiently retrieve values.

• HashMap internally uses an array of linked lists to store key-value pairs.

• When a key-value pair is added, the key is hashed to determine the index in the array where it will be stored.

• If multiple keys hash to the same index, a linked list is used to handle collisions.

• HashMap uses the hashCode() method of keys to calc...read more

Throw is used to explicitly throw an exception in a method, while Throws is used to declare the exceptions that a method may throw.

• Throw is used within a method to throw an exception explicitly.

• Throws is used in the method signature to declare the exceptions that the method may throw.

• Throw is followed by an instance of Throwable class, while Throws is followed by the exception class names separated by commas.

• Example: t...read more

Arrays are fixed in size, while ArrayLists can dynamically resize. ArrayLists provide more flexibility and functionality.

• Arrays have a fixed size, while ArrayLists can dynamically resize.

• ArrayLists can easily add, remove, or modify elements, while arrays require manual shifting of elements.

• Arrays use [] syntax for declaration and initialization, while ArrayLists use the ArrayList class from the Java Collections framewo

ArrayList is resizable array implementation, LinkedList is doubly linked list implementation, Vector is synchronized version of ArrayList.

• ArrayList is faster for accessing elements, LinkedList is faster for adding/removing elements in middle.

• ArrayList uses less memory than LinkedList due to contiguous memory allocation.

• Vector is thread-safe but slower than ArrayList due to synchronization overhead.

Iterate through a hashmap using an iterator in Java

• Create an iterator using the entrySet() method of the hashmap

• Use a while loop to iterate through the hashmap entries

• Access the key and value of each entry using the getKey() and getValue() methods

I have 2 years of experience working with Docker in various projects.

• 2 years of experience working with Docker in various projects

• Proficient in creating Docker containers, managing images, and orchestrating containers using Docker Compose

• Familiar with Docker Swarm and Kubernetes for container orchestration

• Experience in troubleshooting Docker-related issues and optimizing container performance

Yes, I have experience in Kubernetes.

• I have worked on deploying and managing applications on Kubernetes clusters.

• I am familiar with creating and managing Kubernetes resources such as pods, deployments, services, and ingresses.

• I have experience in using tools like kubectl and Helm for interacting with Kubernetes clusters.

• I have implemented CI/CD pipelines using Kubernetes for automated deployment and scaling of applicat

OOP stands for Object-Oriented Programming, a programming paradigm based on the concept of objects.

• OOP focuses on creating objects that contain data and methods to manipulate that data.

• Encapsulation, inheritance, and polymorphism are key principles of OOP.

• Examples of OOP languages include Java, C++, and Python.

Polymorphism in Java refers to the ability of a method to do different things based on the object it is acting upon.

• Types of polymorphism in Java include method overloading and method overriding.

• Method overloading is when multiple methods have the same name but different parameters.

• Method overriding is when a subclass provides a specific implementation of a method that is already defined in its superclass.

Threads in Java allow multiple tasks to run concurrently within a single program.

• Threads are lightweight sub-processes that share the same memory space.

• They are used to improve performance by allowing tasks to run simultaneously.

• Examples include creating a new thread using the Thread class or implementing the Runnable interface.

Spring profile is a way to segregate parts of your application configuration and make it only available in certain environments.

• Spring profiles allow you to define different configurations for different environments such as development, testing, and production.

• You can use @Profile annotation to specify which beans should be loaded based on the active profile.

• Profiles can be activated in various ways such as through app...read more

Annotations used in Spring Security to apply authorization rules before and after a method is called.

• Used in Spring Security to define authorization rules

• @PreAuthorize is used to apply authorization rules before a method is called

• @PostAuthorize is used to apply authorization rules after a method is called

• Both annotations support SpEL expressions for defining rules