Update Exchange

Added JavaDoc.

millions/src/main/java/no/ntnu/gruppe53/Exchange.java

@@ -146,6 +146,12 @@ public void advance() {
         }
     }
 
+    /**
+     * Lists the given amount of stocks sorted by highest increase in sales price since last week.
+     * @param entries amount of stocks to be shown in list
+     * @return a descending list of stocks with the highest price increase since last week
+     * @throws IllegalArgumentException if number of entries in list is negative
+     */
     public List<Stock> getGainers(int entries) {
         if (entries < 0) {
             throw new IllegalArgumentException("Amount of entries in list cannot be negative.");
@@ -159,6 +165,14 @@ public List<Stock> getGainers(int entries) {
                 .collect(Collectors.toList());
     }
 
+    /**
+     * Lists the given amount of stocks sorted by the stocks with the lowest price increase (or
+     * highest price decrease)
+     * @param entries amount of stocks to be shown in the list
+     * @return a descending list of stocks with the highest price decrease or
+     *         lowest price increase
+     * @throws IllegalArgumentException if number of entries in list is negative
+     */
     public List<Stock> getLosers(int entries) {
         if (entries < 0) {
             throw new IllegalArgumentException("Amount of entries in list cannot be negative.");