JAVA Free Section Starter Challenge 35 min

5. Java Collections: ArrayList & HashMap

Overview: Store dynamic data structures using the Java Collections Framework: generic ArrayLists and key-value HashMaps.

Concept & Syntax Guide

Unlike primitive arrays with fixed sizes, Java's `ArrayList<T>` grows dynamically as elements are added. `HashMap<K, V>` provides constant-time performance for key-value lookups.

Hands-On Practice Exercise

Store and Iterate Course Catalog in ArrayList

Create an `ArrayList<String>` for course titles, add "Modern PHP 8" and "React Masterclass", and print the list size.

Target Output: Total Courses Enrolled: 2

Need a hint? Click here to reveal

Hint: Check syntax carefully and make sure your code contains: Total Courses Enrolled: 2

JAVA Code Editor

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import java.util.ArrayList;

public class CourseManager {
    public static void main(String[] args) {
        ArrayList<String> courses = new ArrayList<>();
        courses.add("Modern PHP 8");
        courses.add("React Masterclass");
        System.out.println("Total Courses Enrolled: " + courses.size());
    }
}