10+ Indiglobe IT Solutions Interview Questions and Answers

A functional interface is a single abstract method interface. It can be referred to using a lambda expression.

• Functional interfaces have only one abstract method

• Lambda expressions can be used to implement functional interfaces

• Lambda expressions provide a concise way to write anonymous functions

• Functional interfaces can be used as method parameters or return types

HashMap is a data structure in Java that stores key-value pairs. It is mutable while iterating through it.

• HashMap is part of the Java Collections Framework.

• It allows null values and at most one null key.

• It provides constant-time performance for basic operations like get and put.

• While iterating through a HashMap, it is mutable and can throw ConcurrentModificationException if modified.

• To avoid this, use an Iterator or ConcurrentHashMap.

Various annotations used in SpringBoot

• 1. @SpringBootApplication: Marks the main class of a Spring Boot application

• 2. @RestController: Marks a class as a RESTful controller

• 3. @RequestMapping: Maps HTTP requests to handler methods

• 4. @Autowired: Injects dependencies automatically

• 5. @Component: Marks a class as a Spring component

• 6. @Service: Marks a class as a service component

• 7. @Repository: Marks a class as a repository component

• 8. @Configuration: Marks a class as a source of b...read more

Find duplicate element in array using Java 8 features.

• Convert array to stream using Arrays.stream()

• Use Collectors.groupingBy() to group elements by their occurrence

• Filter the grouped elements to find duplicates

The different bean scopes in Spring are singleton, prototype, request, session, and application.

• Singleton scope creates a single instance of a bean per Spring IoC container.

• Prototype scope creates a new instance of a bean every time it is requested.

• Request scope creates a new instance of a bean for each HTTP request.

• Session scope creates a new instance of a bean for each HTTP session.

• Application scope creates a single instance of a bean per ServletContext.

Sort list of student details by mark.

• Create a custom class Student with attributes like name, mark.

• Implement Comparator interface to sort by mark.

• Use Collections.sort() method to sort the list of students.

The transient keyword in Java is used to indicate that a variable should not be serialized.

• Variables marked as transient are not included in the serialization process

• Transient variables are not saved when an object is serialized and are set to their default values when the object is deserialized

• Useful for excluding sensitive or unnecessary data from being serialized

Java is pass by value

• Java is pass by value, meaning a copy of the variable is passed to a method

• Changes made to the copy inside the method do not affect the original variable

• However, if the variable is an object reference, the reference is passed by value

Method Overloading is having multiple methods with the same name but different parameters. Method Overriding is having a method in a subclass with the same name and parameters as in the superclass.

• Method Overloading is used to provide different ways of calling the same method with different parameters.

• Method Overriding is used to provide a specific implementation of a method that is already provided by its superclass.

• Method Overloading is resolved at compile-time based on the...read more

String Builder is not synchronized, while String Buffer is synchronized.

• String Builder is faster than String Buffer because it is not synchronized.

• String Buffer is thread-safe, while String Builder is not.

• Use String Builder when you do not need thread safety, and String Buffer when you do.

Java 8 introduced several new features including lambda expressions, functional interfaces, streams, and default methods.

• Lambda expressions allow writing concise and functional code.

• Functional interfaces provide a way to define and use lambda expressions.

• Streams enable processing collections of data in a functional and parallel way.

• Default methods allow adding new methods to existing interfaces without breaking compatibility.

• Other features include the new Date and Time API, i...read more

Using Java 8, find the second largest salary from a list of salaries.

• Sort the list of salaries in descending order using streams and lambda expressions.

• Skip the first element (largest salary) and find the first element (second largest salary).

Merge and sort two arrays

• Use the merge sort algorithm to merge and sort the arrays

• Convert the arrays to a list of strings before merging and sorting

• Handle null or empty arrays as special cases

To find the third highest salary in SQL, you can use the 'ORDER BY' clause and 'LIMIT' keyword.

• Write a SQL query to select distinct salaries from the table

• Order the salaries in descending order using the 'ORDER BY' clause

• Use the 'LIMIT' keyword to limit the result to the third row

• Retrieve the third highest salary from the result

Calculate the sum of all elements in a list

• Iterate through the list and add each element to a running total

• Return the total sum at the end

Streams API is a feature in Java that allows for processing sequences of elements efficiently.

• Streams API provides a way to perform operations on collections of objects in a functional style.

• It supports operations like filter, map, reduce, and collect.

• Streams can be sequential or parallel, allowing for efficient processing of large datasets.

• Example: List<String> names = Arrays.asList("Alice", "Bob", "Charlie"); names.stream().filter(name -> name.startsWith("A")).forEach(Syste...read more