10+ The Divy Group of Company Interview Questions and Answers

Remove duplicates from a sorted array in-place and return the length of the modified array.

• Use two pointers approach to track unique elements and duplicates.

• Modify the input array in-place without using extra space.

• Return the length of the modified array.

Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.

• Abstract class can have constructors, fields, and methods, while interface cannot have any of these.

• A class can extend only one abstract class, but can implement multiple interfaces.

• Abstract classes are used to provide a common base for subclasses, while interfaces are used to define a contract for classes to implement.

• Example: Abstract class - Animal with abstract m...read more

Java 8 introduced several new features including lambda expressions, functional interfaces, streams, and the new Date and Time API.

• Lambda expressions: Allow you to treat functionality as a method argument.

• Functional interfaces: Interfaces with a single abstract method, used for lambda expressions.

• Streams: Provide a new abstraction to work with sequences of elements.

• Date and Time API: Improved API for handling date and time operations.

Abstract class can have implemented methods while interface cannot.

• Abstract class can have constructors while interface cannot

• Abstract class can have instance variables while interface cannot

• A class can implement multiple interfaces but can only extend one abstract class

• Java 8 introduced default and static methods in interfaces

Dependency Injection is a design pattern in Spring framework where the objects are provided with their dependencies.

• In Dependency Injection, the dependencies of an object are injected into it rather than the object creating them itself.

• This helps in achieving loose coupling between classes and makes the code more maintainable and testable.

• Spring framework provides various ways to implement Dependency Injection such as constructor injection, setter injection, and field injecti...read more

Collection is an interface while Collections is a utility class in Java.

• Collection is an interface that provides a standard way to represent and manipulate a group of objects.

• Collections is a utility class that provides various methods for working with collections.

• Collection is a single entity while Collections is a group of methods.

• Example: List is a type of Collection while Collections.sort() is a method in Collections class.

• Collection is present in java.util package while ...read more

Program to remove duplicate elements from an array of strings.

• Create a new empty array to store unique elements.

• Iterate through the original array and check if each element is already present in the new array.

• If not present, add it to the new array.

• Return the new array with unique elements.

Constructor is a special method used to initialize objects in Java.

• Constructor has the same name as the class name

• It does not have a return type

• It can be overloaded

• It is called automatically when an object is created

• Example: public class Car { public Car() { // constructor code } }

Java program to find duplicates in an array of strings

• Create a HashSet to store unique elements

• Iterate through the array and check if element is already in the HashSet

• If element is already in the HashSet, it is a duplicate

Optimizing performance involves identifying bottlenecks and implementing efficient solutions.

• Identify and address any inefficient algorithms or data structures

• Optimize database queries and indexing

• Implement caching mechanisms to reduce redundant computations

• Use profiling tools to identify performance bottlenecks

• Consider parallel processing or asynchronous operations for resource-intensive tasks

Method overloading is a feature in Java that allows multiple methods with the same name but different parameters.

• Method overloading is achieved by defining multiple methods with the same name but different parameter types or number of parameters.

• The compiler determines which method to call based on the arguments passed during the method invocation.

• Method overloading improves code readability and reusability.

• Return type alone is not sufficient to differentiate overloaded metho...read more

Create and sort an array of strings in descending order

• Create an array of strings

• Use Arrays.sort() method with Collections.reverseOrder() comparator to sort in descending order

To give security to our application, we can implement various measures such as encryption, authentication, authorization, input validation, and regular security audits.

• Implement encryption to protect sensitive data, such as using SSL/TLS for secure communication.

• Use authentication mechanisms like OAuth, JWT, or multi-factor authentication to verify the identity of users.

• Implement authorization to control access to resources based on user roles and permissions.

• Perform input va...read more

Create an array of strings and add the array

• Declare an array of strings

• Initialize the array with values

• Use a loop to add the values to the array

HashSet is an unordered collection of unique elements, while Hashtable is a synchronized collection of key/value pairs.

• HashSet does not allow duplicate elements, while Hashtable does not allow duplicate keys.

• HashSet does not maintain insertion order, while Hashtable does not guarantee any order.

• HashSet allows null values, while Hashtable does not allow null keys or values.