doc portfolio class

added det documentation for the portfolio class

src/main/java/edu/ntnu/idi/idatt2003/g40/mappe/Portfolio.java

@@ -4,36 +4,74 @@
 import java.util.List;
 import java.util.Objects;
 
+/**
+ * Represents a player's portfolio of shares.
+ * <p>
+ * The portfolio stores shares and provides operations for adding, removing,
+ * retrieving and checking ownership of shares.
+ * </p>
+ */
 public class Portfolio {
 
     private final List<Share> shares = new ArrayList<>();
 
+    /**
+     * Creates an empty portfolio.
+     */
     public Portfolio() {
         // Intentionally empty
     }
 
+    /**
+     * Adds a share to the portfolio.
+     *
+     * @param share the share to add
+     * @return {@code true} if the share was added, {@code false} otherwise
+     */
     public boolean addShare(Share share) {
         Objects.requireNonNull(share, "share cannot be null");
         return shares.add(share);
     }
 
+    /**
+     * Removes a share from the portfolio.
+     *
+     * @param share the share to remove
+     * @return {@code true} if the share was removed, {@code false} if it was not present
+     */
     public boolean removeShare(Share share) {
         Objects.requireNonNull(share, "share cannot be null");
         return shares.remove(share);
     }
 
-
+    /**
+     * Returns an immutable snapshot of all shares in the portfolio.
+     *
+     * @return a list of shares
+     */
     public List<Share> getShares() {
         return List.copyOf(shares);
     }
 
+    /**
+     * Returns an immutable snapshot of all shares whose stock symbol matches the given symbol.
+     *
+     * @param symbol the stock symbol to match
+     * @return a list of shares matching the symbol
+     */
     public List<Share> getShares(String symbol) {
         Objects.requireNonNull(symbol, "symbol cannot be null");
         return shares.stream()
                 .filter(s -> symbol.equalsIgnoreCase(s.getStock().getSymbol()))
                 .toList();
     }
 
+    /**
+     * Checks whether the given share exists in the portfolio.
+     *
+     * @param share the share to check
+     * @return {@code true} if the portfolio contains the share, otherwise {@code false}
+     */
     public boolean contains(Share share) {
         Objects.requireNonNull(share, "share cannot be null");
         return shares.contains(share);