Observer in Stock Market App
This program integrates Observer pattern in stock market app.
Problem Statement
Write a Java program where Stock notifies multiple investors when price changes.
Source Code
| 1 | import java.util.*; |
| 2 | interface Investor { void update(double price); } |
| 3 | class Stock { |
| 4 | List<Investor> investors=new ArrayList<>(); |
| 5 | double price; |
| 6 | void addInvestor(Investor i){ investors.add(i); } |
| 7 | void setPrice(double p){ price=p; notifyInvestors(); } |
| 8 | void notifyInvestors(){ for(Investor i:investors) i.update(price); } |
| 9 | } |
| 10 | class ConcreteInvestor implements Investor { |
| 11 | String name; |
| 12 | ConcreteInvestor(String n){ name=n; } |
| 13 | public void update(double price){ System.out.println(name+" notified: Price = "+price); } |
| 14 | } |
| 15 | public class StockMarketApp { |
| 16 | public static void main(String[] args) { |
| 17 | System.out.println("Eduinq Stock Market App"); |
| 18 | Stock s=new Stock(); |
| 19 | s.addInvestor(new ConcreteInvestor("Investor1")); |
| 20 | s.addInvestor(new ConcreteInvestor("Investor2")); |
| 21 | s.setPrice(120.5); |
| 22 | } |
| 23 | } |
Program Output
Eduinq Stock Market App Investor1 notified: Price = 120.5 Investor2 notified: Price = 120.5
Explanation
Stock acts as Subject, Investors as Observers. - Price change triggers notifications. - This models real world enterprise apps like trading platforms. Conclusion: Shows Observer integration in enterprise apps.