Modify findBuyOrders() to take care of the case when buy order has more stock than the sell order

src/OrderMatching.java

@@ -19,10 +19,12 @@ public class OrderMatching {
 	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();
+				b.getPrice() >= s.getPrice();
 	}
 	
+	/*
+	 * Finds all buy orders for current sell order
+	 */
 	ArrayList<BuyOrder> findBuyOrders(SellOrder s) {
 		ArrayList<BuyOrder> matchedOrders = new ArrayList<>();
 		
@@ -34,11 +36,28 @@ public class OrderMatching {
 			
 			// 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());
+				int qty = s.getQty() - b.getQty();
+				
+				if (qty >= 0) {				
+					// modify sell order quantity to prevent 
+					// repeated purchases
+					s.setQty(s.getQty() - b.getQty());
+					matchedOrders.add(b);
+				} else {
+					s.setQty(0);
+				
+					// create a temporary BuyOrder with quantity equal to 
+					// the remaining stocks in sell order
+					BuyOrder _b = new BuyOrder(b);
+					_b.setQty(s.getQty());
+					// add it to buy orders queue
+					matchedOrders.add(_b);
+					
+					// modify buy order's quantity to reflect quantity
+					// remaining after trade
+					b.setQty(b.getQty() - s.getQty());
+				}
 			}	
 		}