add methods for returning top gainers and bottom losers of stocks in …

src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Exchange.java

@@ -23,7 +23,6 @@ public class Exchange {
   private int week;
   private Map<String, Stock> stockMap;
   private Random random;
-  private List<Stock> stocks;
 
   /**
    * Constructs a new {@code Exchange} with a name and a list of stocks.
@@ -36,7 +35,6 @@ public Exchange(String name, List<Stock> stocks) {
     this.week = 0;
     this.stockMap = new HashMap<String, Stock>();
     this.random = new Random();
-    this.stocks = stocks;
     for (Stock stock : stocks) {
       stockMap.put(stock.getSymbol(), stock);
     }
@@ -79,7 +77,7 @@ public Stock getStock(String symbol) {
   public List<Stock> findStocks(String searchTerm) {
     List<Stock> foundStocks = new ArrayList<>();
 
-    for (Stock stock : stocks) {
+    for (Stock stock : stockMap.values()) {
       if (stock.getCompany().equals(searchTerm)) {
         foundStocks.add(stock);
       }
@@ -116,7 +114,7 @@ public Transaction buy(String symbol, BigDecimal quantity, Player player) {
    *
    * @param share the share to sell
    * @param player the player performing the sale
-   * @return a {@code Sale} transaction representing the sale
+   * @return a sale transaction representing the sale
    */
   public Transaction sell(Share share, Player player) {
     SaleCalculator saleCalculator = new SaleCalculator(share);
@@ -130,4 +128,26 @@ public Transaction sell(Share share, Player player) {
   public void advance() {
     week += 1;
   }
+
+  /**
+   * Returns the top stocks by price change given a limit.
+   *
+   * @param limit the number of stocks to return
+   * @return a list of stocks sorted by price change
+   */
+  public List<Stock> getGainers(int limit) {
+    return stockMap.values().stream().sorted((a, b) -> b.getLatestPriceChange()
+        .compareTo(a.getLatestPriceChange())).limit(limit).toList();
+  }
+
+  /**
+   * Returns the bottom stocks by price change given a limit.
+   *
+   * @param limit the number of stocks to return
+   * @return a list of stocks sorted by price change
+   */
+  public List<Stock> getLosers(int limit) {
+    return stockMap.values().stream().sorted((a, b) -> a.getLatestPriceChange()
+        .compareTo(b.getLatestPriceChange())).limit(limit).toList();
+  }
 }

src/main/java/edu/ntnu/idi/idatt2003/gruppe42/Model/Stock.java

@@ -37,7 +37,7 @@ public String getCompany() {
   }
 
   public BigDecimal getSalesPrice() {
-    return prices.get(prices.size() - 1);
+    return prices.isEmpty() ? BigDecimal.ZERO : prices.get(prices.size() - 1);
   }
 
   /**
@@ -60,7 +60,11 @@ public BigDecimal getLowestPrice() {
     return prices.stream().min(BigDecimal::compareTo).orElse(BigDecimal.ZERO);
   }
 
-  public BigDecimal getLatestPrice() {
-    return prices.isEmpty() ? BigDecimal.ZERO : prices.get(prices.size() - 1);
+  public BigDecimal getLatestPriceChange() {
+    if (prices.size() < 2) {
+      return BigDecimal.ZERO;
+    }
+    return prices.get(prices.size() - 1)
+        .subtract(prices.get(prices.size() - 2));
   }
 }