In Java, a Set is a collection that: Stores unique elements (no duplicates allowed). Does not guarantee order (depending on the implementation). Is part of the Java Collections Framework (java.util package). 🔑 Main Set Implementations 1. HashSet Backed by a hash table. Elements are unordered. Fast for add(), remove(), contains() (O(1) on average). import…
In Java, handling dates and calendars can be done using different APIs depending on which version of Java you’re working with: ✅ Modern Approach (Java 8 and later) Java 8 introduced the java.time package (JSR-310), which provides a much better and cleaner API for date and time handling. Common Classes: LocalDate → Date without…
1. StringTokenizer Used to split strings into tokens based on delimiters.(Note: It’s a legacy class; String.split() or Scanner is usually preferred.) import java.util.StringTokenizer; public class Example { public static void main(String[] args) { String text = "Java,Python,C++"; StringTokenizer st = new StringTokenizer(text, ","); while (st.hasMoreTokens()) { System.out.println(st.nextToken()); } } } import java.util.StringTokenizer; public class…
In Java 11, HttpClient was introduced as part of the java.net.http package, providing a modern, fully asynchronous, and flexible HTTP client API to replace the older HttpURLConnection. It supports HTTP/1.1, HTTP/2, synchronous and asynchronous requests, and built-in support for handling JSON, time-outs, redirects, and authentication. Here’s a detailed overview and examples: 1. Creating an…
1. isBlank() Checks if a string is empty or contains only whitespace characters. String s1 = " "; String s2 = "Hello"; System.out.println(s1.isBlank()); // true System.out.println(s2.isBlank()); // false String s1 = " "; String s2 = "Hello"; System.out.println(s1.isBlank()); // true System.out.println(s2.isBlank()); // false Difference from isEmpty():isEmpty() only checks if the length is 0. isBlank()…
What is a Record in Java? A record is a special kind of class introduced in Java 16 (preview earlier), and fully standard from Java 16 onwards, designed to model immutable data. Think of it as a concise way to define a class whose main purpose is to store data. A record automatically provides:…
In Java, a stack is a data structure that follows the LIFO (Last In, First Out) principle. This means the most recently added element is the first one to be removed. 1. Using java.util.Stack Java provides a built-in Stack class in java.util package. Example: import java.util.Stack; public class StackExample { public static void main(String[]…
In Java 21, sequenced collections are part of the java.util package and are designed to maintain element insertion order, meaning the order in which elements were added is preserved. This is different from regular collections like HashSet or HashMap which do not guarantee order. Java 21 introduces enhancements to sequenced collections, building on previous…
1. What is a Sealed Class? A sealed class is a class that restricts which other classes or interfaces can extend or implement it. It allows you to control the inheritance hierarchy more strictly than abstract classes. Think of it like saying: “Only these specific classes are allowed to inherit from me.” 2. Why…
🔹 What are Generics in Java? Generics allow you to write classes, interfaces, and methods where the type of data is specified as a parameter.This makes your code type-safe, reusable, and easier to read. Instead of writing separate classes/methods for different data types, you can use type parameters (<T>, <E>, <K, V>, etc.). 🔹…