Testdome Java Questions And Answers ❲Desktop❳

Here’s a detailed feature concept for , designed as an interactive study and skill-assessment tool within the TestDome platform or as a standalone mini-app. Feature Name: "Java Skill Builder: Interactive Q&A with Smart Hints" 🎯 Goal Help Java developers (junior to mid-level) prepare for technical interviews and coding assessments by solving realistic, topic-focused TestDome-style questions with step-by-step guidance, automated feedback, and performance tracking. 🧩 Core Components 1. Question Library Organized by difficulty and topic:

/** * Implement a method that returns the first non-repeating character in a string. * If none exists, return null. * Example: "swiss" -> 'w' */ public Character firstNonRepeating(String s) // Your code here

import java.util.LinkedHashMap; import java.util.Map; public class FirstNonRepeating public static Character find(String s) s.isEmpty()) return null;

| Category | Example Topics | |----------|----------------| | OOP | Inheritance, polymorphism, encapsulation, abstraction | | Core Java | Collections, streams, lambdas, exceptions | | Algorithms | Sorting, recursion, two-pointer, sliding window | | Data Structures | Lists, sets, maps, queues, trees | | Concurrency | Threads, synchronized , ExecutorService | | Java 8+ | Optional, Stream API, method references, new Date/Time API |

Map<Character, Integer> countMap = new LinkedHashMap<>(); for (char c : s.toCharArray()) countMap.put(c, countMap.getOrDefault(c, 0) + 1); for (Map.Entry<Character, Integer> entry : countMap.entrySet()) if (entry.getValue() == 1) return entry.getKey(); return null;