Implement method to find all buy orders for a sell order

src/OrderMatching.java

@@ -2,8 +2,8 @@ import java.util.*;
 
 public class OrderMatching {
 
-	List<SellOrder> sellOrderQueue = new LinkedList<>();
-	List<BuyOrder> buyOrderQueue = new LinkedList<>();
+	private List<SellOrder> sellOrderQueue = new LinkedList<>();
+	private List<BuyOrder> buyOrderQueue = new LinkedList<>();
 	
 	/*
 	 * Checks if the order is valid
@@ -12,4 +12,47 @@ public class OrderMatching {
 		return order.getQty() > 0 && order.getPrice() > 0.0;
 	}
 	
+	/*
+	 * Checks if trade can happen between buy order and
+	 * sell order
+	 */
+	boolean buySellOrderMatch(BuyOrder b, SellOrder s) {
+		return !b.getCustomer().equals(s.getCustomer()) &&
+				b.getStock().equals(s.getStock()) &&
+				b.getPrice() >= s.getPrice() &&
+				b.getQty() <= s.getQty();
+	}
+	
+	ArrayList<BuyOrder> findBuyOrders(SellOrder s) {
+		ArrayList<BuyOrder> matchedOrders = new ArrayList<>();
+		
+		// Iterate over buy orders queue
+		for (BuyOrder b : buyOrderQueue) {
+			// if current sell orders have already found all buyers,
+			// exit the loop
+			if (s.getQty() <= 0) break;
+			
+			// check if trade is possible
+			if (buySellOrderMatch(b, s)) {
+				matchedOrders.add(b);
+				
+				// modify sell order quantity to prevent 
+				// repeated purchases
+				s.setQty(s.getQty() - b.getQty());
+			}	
+		}
+		
+		// if there is still some stocks to sell
+		// add it to sell orders queue
+		if (s.getQty() > 0) sellOrderQueue.add(s);
+		
+		// remove all buy orders that were matched from
+		// buy order queue
+		for (BuyOrder b : matchedOrders) {
+			buyOrderQueue.remove(b);
+		}
+		
+		return matchedOrders;
+	}
+	
 }