Add new exercise task

Author: tboychuk

account-analytics/src/main/java/com.bobocode/AccountAnalytics.java

@@ -7,6 +7,9 @@
 import java.time.Month;
 import java.util.*;
 
+import static java.util.stream.Collectors.mapping;
+import static java.util.stream.Collectors.toMap;
+
 /**
  * Implement methods using Stream API
  */
@@ -117,6 +120,17 @@ public Map<Long, Account> collectAccountsById() {
         throw new UnsupportedOperationException("It's your job to implement this method"); // todo
     }
 
+    /**
+     * Filters accounts by the year when an account was created. Collects account balances by its emails into a {@link Map}.
+     * The key is {@link Account#email} and the value is {@link Account#balance}
+     *
+     * @param year the year of account creation
+     * @return map of account by its ids the were created in a particular year
+     */
+    public Map<String, BigDecimal> collectBalancesByIdForAccountsCreatedOn(int year) {
+        throw new UnsupportedOperationException("It's your job to implement this method"); // todo
+    }
+
     /**
      * Returns a {@link Map} where key is {@link Account#lastName} and values is a {@link Set} that contains first names
      * of all accounts with a specific last name.

account-analytics/src/test/java/com/bobocode/AccountAnalyticsTest.java

@@ -155,6 +155,15 @@ public void testCollectAccountsById() {
         assertEquals(accounts.get(3), idToAccountMap.get(4L));
     }
 
+    @Test
+    public void testCollectBalancesByIdForAccountsCreatedOn() {
+        Account account = accounts.get(3);
+
+        Map<String, BigDecimal> emailToBalanceMap = analytics.collectBalancesByIdForAccountsCreatedOn(account.getCreationDate().getYear());
+
+        assertEquals(Map.of(account.getEmail(), account.getBalance()), emailToBalanceMap);
+    }
+
     @Test
     public void testGroupFirstNamesByLastNames() {
         Map<String, Set<String>> lastToFirstNamesMap = analytics.groupFirstNamesByLastNames();