added transaction recording

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/abaproblem/Account.java

@@ -1,34 +1,49 @@
 package com.baeldung.abaproblem;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 
 public class Account {
 
     private AtomicInteger balance = new AtomicInteger(0);
+    private List<Long> transactionDates = new ArrayList<>();
 
     public int getBalance() {
         return balance.get();
     }
 
+    public List<Long> getTransactionDates() {
+        return transactionDates;
+    }
+
     public boolean withdraw(int amount) throws InterruptedException {
         int current = getBalance();
         if (current < amount) {
             throw new RuntimeException("Not sufficient balance");
         }
         precessBalance();
-        return balance.compareAndSet(current, current - amount);
+        boolean result = balance.compareAndSet(current, current - amount);
+        if (result) {
+            transactionDates.add(System.currentTimeMillis());
+        }
+        return result;
     }
 
     private void precessBalance() throws InterruptedException {
-        if ("thread 1".equals(Thread.currentThread().getName())) {
+        if ("thread1".equals(Thread.currentThread().getName())) {
             TimeUnit.SECONDS.sleep(2);
         }
     }
 
     public boolean deposit(int amount) {
         int current = balance.get();
-        return balance.compareAndSet(current, current + amount);
+        boolean result = balance.compareAndSet(current, current + amount);
+        if (result) {
+            transactionDates.add(System.currentTimeMillis());
+        }
+        return result;
     }
 
 }

core-java-modules/core-java-concurrency-advanced-3/src/test/java/com/baeldung/abaproblem/AccountUnitTest.java

@@ -4,6 +4,7 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
@@ -19,6 +20,7 @@ public class AccountUnitTest {
     @Test
     public void zeroBalanceInitializationTest() {
         assertEquals(0, account.getBalance());
+        assertTrue(account.getTransactionDates().isEmpty());
     }
 
     @Test
@@ -55,7 +57,9 @@ public class AccountUnitTest {
         final int amountToWithdrawByThreadB = 10;
         final int amountToDepositByThreadB = 10;
 
+        assertTrue(account.getTransactionDates().isEmpty());
         account.deposit(defaultBalance);
+        assertEquals(1, account.getTransactionDates().size());
 
         Thread threadA = new Thread(() -> {
             try {
@@ -64,7 +68,7 @@ public class AccountUnitTest {
             } catch (InterruptedException e) {
                 throw new RuntimeException(e);
             }
-        }, "tread 1");
+        }, "thread1");
 
         Thread threadB = new Thread(() -> {
 
@@ -80,7 +84,7 @@ public class AccountUnitTest {
             // thread 1 didn't finish yet, so the original value will be in place for it
             assertEquals(defaultBalance, account.getBalance());
 
-        }, "thread 2");
+        }, "thread2");
 
         threadA.start();
         threadB.start();
@@ -89,5 +93,11 @@ public class AccountUnitTest {
 
         // compareAndSet operation succeeds for thread 1
         assertEquals(defaultBalance - amountToWithdrawByThreadA, account.getBalance());
+
+        //but there are other transactions
+        assertNotEquals(2, account.getTransactionDates().size());
+
+        // thread 2 did two modifications as well
+        assertEquals(4, account.getTransactionDates().size());
     }
 }