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Showing posts from September, 2023

Efficiently Removing Duplicates from Array , ArrayList and List of Employee using Java 8 Streams

  Introduction: In modern Java programming, streams are a powerful tool for working with collections in a concise and efficient way. Removing Duplicates from Arrays using Java 8 Streams: Suppose you have an array of integers with duplicates, and you want to create a new array containing only distinct values then follow below steps Convert the array into a stream. Use the distinct() method to eliminate duplicates. Convert the stream back into an array using toArray() . import java.util.Arrays; public class RemoveDuplicatesFromArray { public static void main (String[] args) { Integer[] array = { 1 , 2 , 2 , 3 , 4 , 4 , 5 }; // Step 1: Convert the array into a stream. // Step 2: Use the `distinct()` method to eliminate duplicates. // Step 3: Convert the stream back into an array using `toArray()`. Integer[] distinctArray = Arrays.stream(array) .distinct() .toArray(Integer[]:: new ); Syst...

Difference between HashMap vs. HashSet and HashMap vs. Concurrent HashMap in Java?

In Java, HashMap, HashSet, and Concurrent HashMap are essential components of the Java Collections Framework, each serving distinct purposes when it comes to storing and managing data. In this blog post, we will explore the differences between HashMap vs. HashSet and HashMap vs. Concurrent HashMap, complete with examples to clarify their use cases. HashMap vs. HashSet HashMap HashMap is a data structure used to store key-value pairs. It uses a hashing mechanism to quickly retrieve values based on their keys. Here are some key characteristics of HashMap: Allows duplicate values but not duplicate keys. Provides efficient key-value retrieval using hashing. Does not maintain order (the order of elements is not guaranteed). Accepts null values and a single null key. HashSet HashSet , on the other hand, is used to store a collection of unique values. It does not allow duplicate elements. Here are some key characteristics of HashSet: Stores only unique values (no duplicate elements). Does no...

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Using Java 8 Streams to Find the Second-Highest Salary in an Employee List

To find the second-highest salary from a list of employees using Java 8 streams, you can follow these steps: Create a list of employees with their salaries. Use Java 8 streams to sort the employees by salary in descending order. Skip the first element (which is the employee with the highest salary). Get the first element of the remaining stream (which is the employee with the second-highest salary). Example code: java import java.util.ArrayList; import java.util.List; class Employee { private String name; private double salary; public Employee (String name, double salary) { this .name = name; this .salary = salary; } public double getSalary () { return salary; } } public class SecondHighestSalary { public static void main (String[] args) { List<Employee> employees = new ArrayList <>(); employees.add( new Employee ( "John" , 60000.0 )); employees.add( new Employe...

Top 20 Exception Handling Interview Questions and Answers for Experienced Java Developers

Introduction: Exception handling is a crucial aspect of Java development, ensuring robust and error-tolerant code. Experienced Java developers are expected to have a deep understanding of exception handling mechanisms. In this blog post, we'll explore the top 20 interview questions related to exception handling, accompanied by detailed answers and sample code snippets to help you prepare for your next Java interview. 1. What is an exception in Java? An exception is an event that disrupts the normal flow of a program. In Java, exceptions are objects that represent errors or abnormal situations during runtime. java try { // Code that may throw an exception } catch (ExceptionType e) { // Code to handle the exception } 2. Differentiate between checked and unchecked exceptions. Checked exceptions are checked at compile-time, and the programmer is forced to either catch them or declare that the method throws them. Unchecked exceptions, on the other hand, are not checked at ...

A Deeper Look into the Java 8 Date and Time API with Q&A

  Understanding Java 8 Date and Time API: The Date and Time API introduced in Java 8 is part of the java.time package, providing classes to represent dates, times, durations, and intervals. This new API addresses many issues found in the old java.util.Date and java.util.Calendar classes, such as immutability, thread safety, and improved functionality. Benefits of Java 8 Date and Time API: Immutability : Date and time objects in the java.time package are immutable, making them thread-safe and eliminating issues related to mutability. Clarity and Readability : The API introduces clear and intuitive classes like LocalDate , LocalTime , and LocalDateTime , making code more readable and maintainable. Extensibility : It offers extensibility through the Temporal and TemporalAccessor interfaces, allowing developers to create custom date and time types. Comprehensive Functionality : The API provides comprehensive functionality for date and time manipulation, formatting, parsing, and a...

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