Java-code.txt

import java.util.HashMap;
import java.util.Map;
import java.util.Random;

public class LinkShortener {
    private Map<String, String> shortToLongMap;
    private Map<String, String> longToShortMap;
    private Random random;
    private static final String CHARACTERS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    private static final int SHORT_URL_LENGTH = 7;  

    public LinkShortener() {
        this.shortToLongMap = new HashMap<>();
        this.longToShortMap = new HashMap<>();
        this.random = new Random();
    }

    
    public String shortenURL(String longUrl) {
        if (longToShortMap.containsKey(longUrl)) {
            return longToShortMap.get(longUrl);  
        }

        String shortUrl = generateShortURL();
        shortToLongMap.put(shortUrl, longUrl);
        longToShortMap.put(longUrl, shortUrl);
        return shortUrl;
    }

   
    public String expandURL(String shortUrl) {
        if (shortToLongMap.containsKey(shortUrl)) {
            return shortToLongMap.get(shortUrl);
        } else {
            return "Short URL does not exist in the system.";
        }
    }

    
    private String generateShortURL() {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < SHORT_URL_LENGTH; i++) {
            int index = random.nextInt(CHARACTERS.length());
            sb.append(CHARACTERS.charAt(index));
        }
        return sb.toString();
    }

    public static void main(String[] args) {
        LinkShortener linkShortener = new LinkShortener();

        
        String longUrl1 = "https://www.example.com/articles/how-to-use-java";
        String longUrl2 = "https://www.example.com/products/java-programming-book";

        String shortUrl1 = linkShortener.shortenURL(longUrl1);
        String shortUrl2 = linkShortener.shortenURL(longUrl2);

        System.out.println("Shortened URLs:");
        System.out.println(shortUrl1);
        System.out.println(shortUrl2);

        
        String expandedUrl1 = linkShortener.expandURL(shortUrl1);
        String expandedUrl2 = linkShortener.expandURL(shortUrl2);

        System.out.println("\nExpanded URLs:");
        System.out.println(expandedUrl1);
        System.out.println(expandedUrl2);
    }
}