Mediator pattern java

We start by createing an *interface* in which we call the Mediator.

public interface Mediator {
    public void saleOffer(String stock, int shares, int collCode);
    public void buyOffer(String stock, int shares, int collCode);
    public void addColleague(Colleague colleague);
}

We also want to create an abstract class called the Colleague.

public abstract class Colleague {
    private Mediator mediator;
    private int colleagueCode;
    public Colleague(Mediator newMediator){
        mediator = newMediator;
        mediator.addColleague(this);
    }
    public void saleOffer(String stock, int shares){
        mediator.saleOffer(stock, shares, this.colleagueCode);
    }
    public void buyOffer(String stock, int shares){
        mediator.buyOffer(stock, shares, this.colleagueCode);
    }
    public void setCollCode(int collCode){ colleagueCode = collCode; }
}

Let's now create a class that will be the **StockMediator**.

import java.util.ArrayList;

public class StockMediator implements Mediator{
    private ArrayList<Colleague> colleagues;
    private ArrayList<StockOffer> stockBuyOffers;
    private ArrayList<StockOffer> stockSaleOffers;
    private int colleagueCodes = 0;
    public StockMediator(){
        colleagues = new ArrayList<Colleague>();
        stockBuyOffers = new ArrayList<StockOffer>();
        stockSaleOffers = new ArrayList<StockOffer>();
    }
    public void addColleague(Colleague newColleague){
        colleagues.add(newColleague);
        colleagueCodes++;
        newColleague.setCollCode(colleagueCodes);
    }
    public void saleOffer(String stock, int shares, int collCode) {
        boolean stockSold = false;
        for(StockOffer offer: stockBuyOffers){
            if((offer.getStockSymbol() == stock) && (offer.getstockShares() == shares)){
                System.out.println(shares + " shares of " + stock +
                        " sold to colleague code " + offer.getCollCode());
                stockBuyOffers.remove(offer);
                stockSold = true;
            }
            if(stockSold){ break; }
        }
        if(!stockSold) {
            System.out.println(shares + " shares of " + stock +
                    " added to inventory");
            StockOffer newOffering = new StockOffer(shares, stock, collCode);
            stockSaleOffers.add(newOffering);
        }
    }
    @Override
    public void buyOffer(String stock, int shares, int collCode) {
        boolean stockBought = false;
        for(StockOffer offer: stockSaleOffers){
            if((offer.getStockSymbol() == stock) && (offer.getstockShares() == shares)){
                System.out.println(shares + " shares of " + stock +
                        " bought by colleague code " + offer.getCollCode());
                stockSaleOffers.remove(offer);
                stockBought = true;
            }
            if(stockBought){ break; }
        }
        if(!stockBought) {
            System.out.println(shares + " shares of " + stock +
                    " added to inventory");
            StockOffer newOffering = new StockOffer(shares, stock, collCode);
            stockBuyOffers.add(newOffering);
        }
    }
    public void getstockOfferings(){
        System.out.println("\nStocks for Sale");
        for(StockOffer offer: stockSaleOffers){
            System.out.println(offer.getstockShares() + " of " + offer.getStockSymbol());
        }
        System.out.println("\nStock Buy Offers");
        for(StockOffer offer: stockBuyOffers){
            System.out.println(offer.getstockShares() + " of " + offer.getStockSymbol());
        }
    }
}

Now let's create a class we call StockOffer.

public class StockOffer {
    private int stockShares = 0;
    private String stockSymbol = "";
    private int colleagueCode = 0;
    public StockOffer(int numOfShares, String stock, int collCode){

        stockShares = numOfShares;
        stockSymbol = stock;
        colleagueCode = collCode;

    }

    public int getstockShares() { return stockShares; }
    public String getStockSymbol() { return stockSymbol; }
    public int getCollCode() { return colleagueCode; }
}

Now let's create another stock offering classes we call **GormanSlacks**.

public class GormanSlacks extends Colleague{
    public GormanSlacks(Mediator newMediator) {
        super(newMediator);
        System.out.println("Gorman Slacks signed up with the stockexchange\n");
    }
}

Let's create another stock offering classes we call **JTPoorman**.

public class JTPoorman extends Colleague{
    public JTPoorman(Mediator newMediator) {
        super(newMediator);
        System.out.println("JT Poorman signed up with the stockexchange\n");
    }
}

Let's put tis all togeher in a main method.

public class TestStockMediator {
    public static void main(String[] args){
        StockMediator nyse = new StockMediator();
        GormanSlacks broker = new GormanSlacks(nyse);
        JTPoorman broker2 = new JTPoorman(nyse);
        broker.saleOffer("MSFT", 100);
        broker.saleOffer("GOOG", 50);
        broker2.buyOffer("MSFT", 100);
        broker2.saleOffer("NRG", 10);
        broker.buyOffer("NRG", 10);
        nyse.getstockOfferings();
    }
}

When we compile an run we should have,

Gorman Slacks signed up with the stockexchange

JT Poorman signed up with the stockexchange

100 shares of MSFT added to inventory
50 shares of GOOG added to inventory
100 shares of MSFT bought by colleague code 1
10 shares of NRG added to inventory
10 shares of NRG bought by colleague code 2

Stocks for Sale
50 of GOOG

Stock Buy Offers

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