10+ Ernst & Young Technology Consultant Interview Questions and Answers for Freshers

Find the smallest subarray in an array with exactly K distinct elements.

• Use a sliding window approach to keep track of the subarray with K distinct elements.

• Use a hashmap to store the frequency of each element in the window.

• Update the window by expanding or shrinking based on the number of distinct elements.

• Return the smallest subarray with K distinct elements and the smallest leftmost index.

ArrayList is non-synchronized and Vector is synchronized in Java.

• ArrayList is not synchronized, while Vector is synchronized.

• ArrayList is faster than Vector.

• Vector is thread-safe, while ArrayList is not.

• Example: ArrayList<String> list = new ArrayList<>(); Vector<String> vector = new Vector<>();

HashSet is a collection of unique elements, while HashMap is a key-value pair mapping.

• HashSet does not allow duplicate elements, HashMap allows duplicate keys but not values.

• HashSet uses a hash table to store elements, HashMap uses key-value pairs.

• Example: HashSet<String> set = new HashSet<>(); HashMap<String, Integer> map = new HashMap<>();

HashMap and Hashtable are both data structures in Java used to store key-value pairs, but Hashtable is synchronized while HashMap is not.

• HashMap allows null values and one null key, while Hashtable does not allow null keys or values.

• HashMap is not synchronized and is not thread-safe, while Hashtable is synchronized and thread-safe.

• HashMap is faster than Hashtable for most operations, as it is not synchronized.

• HashMap is part of the Java Collections Framework, while Hashtable ...read more

The @RestController annotation in Spring Boot is used to define a class as a RESTful controller.

• Used to create RESTful web services in Spring Boot

• Combines @Controller and @ResponseBody annotations

• Eliminates the need for @ResponseBody annotation on each method

• Returns data directly in the response body as JSON or XML

Java Strings are immutable to ensure thread safety, security, and optimization.

• Immutable strings prevent accidental changes, ensuring data integrity.

• String pooling allows for memory optimization by reusing common strings.

• Thread safety is guaranteed as strings cannot be modified concurrently.

• Security is enhanced as sensitive information cannot be altered once set.

Java 8 program to iterate through a Stream using forEach method

• Create a Stream of elements using Stream.of() or any other method

• Use the forEach() method to iterate through the Stream and perform an action on each element

• Example: Stream.of(1, 2, 3, 4, 5).forEach(System.out::println);

Spring Boot is a framework that simplifies the development of Java applications by providing pre-configured setups.

• Auto-configuration: Spring Boot automatically configures the application based on dependencies added to the project.

• Embedded server: Spring Boot comes with an embedded Tomcat, Jetty, or Undertow server for easy deployment.

• Actuator: Provides production-ready features like monitoring, metrics, and health checks for the application.

JIT compiler stands for Just-In-Time compiler, which compiles code during runtime for improved performance.

• JIT compiler translates bytecode into machine code at runtime

• It helps in optimizing performance by compiling frequently executed code

• Examples include Java HotSpot JIT compiler and .NET JIT compiler

MVC in Spring is a design pattern that separates an application into three main components: Model, View, and Controller.

• Model represents the data and business logic of the application.

• View is responsible for rendering the user interface based on the data from the Model.

• Controller acts as an intermediary between Model and View, handling user input and updating the Model accordingly.

• Spring MVC provides annotations like @Controller, @RequestMapping, and @ModelAttribute to implem...read more

Spring Boot is a framework that simplifies the development of Java applications by providing pre-configured settings and tools.

• Spring Boot eliminates the need for manual configuration by providing defaults for most settings.

• It includes embedded servers like Tomcat, Jetty, or Undertow, making it easy to run applications as standalone JAR files.

• Spring Boot also offers production-ready features like metrics, health checks, and externalized configuration.

• It allows developers to q...read more

Java 8 streams are a sequence of elements that support functional-style operations.

• Streams allow for processing sequences of elements in a functional way.

• They can be created from various data sources like collections, arrays, or I/O channels.

• Operations like filter, map, reduce, and collect can be performed on streams.

• Streams are lazy, meaning intermediate operations are only executed when a terminal operation is called.

• Example: List<String> names = Arrays.asList("Alice", "Bob...read more