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Mastering HashMap in Java: How It Works Internally, Handling Hash Collisions, and Java 8 Improvements

HashMap is one of the most commonly used data structures in Java. It is a part of the Java Collections Framework and is used to store key-value pairs. In this blog post, we will dive into how HashMap works internally, what hash collisions are, and explore some enhancements introduced in Java 8. How HashMap Internally Works At its core, a HashMap uses a data structure called an array to store key-value pairs. Each key is associated with a specific index in the array through a process called hashing. Here's a simplified overview of how it works: Hashing : When you put a key-value pair into a HashMap, the HashMap first calculates a hash code for the key. This hash code is an integer value that represents the key and is used to determine the index where the key-value pair will be stored in the array. Index Calculation : The hash code is then processed to calculate an index within the array. This is typically done by taking the hash code modulo the size of the array. The result is the ...
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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...
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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 ...
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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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