Move code to core-java-modules/core-java-concurrency-advanced-3Add

Add missing 'Unit' in test name

core-java-modules/core-java-concurrency-advanced-3/src/main/java/com/baeldung/atomicstampedreference/SafeAccount.java

@@ -0,0 +1,34 @@
+package com.baeldung.atomicstampedreference;
+
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicStampedReference;
+
+public class SafeAccount {
+
+    private AtomicInteger stamp = new AtomicInteger(0);
+    private AtomicStampedReference<Integer> balance = new AtomicStampedReference<>(0, 0);
+
+    public int getBalance() {
+        return this.balance.get(new int[1]);
+    }
+
+    public int getStamp() {
+        int[] stamps = new int[1];
+        this.balance.get(stamps);
+        return stamps[0];
+    }
+
+    public boolean deposit(int funds) {
+        int[] stamps = new int[1];
+        int current = this.balance.get(stamps);
+        int newStamp = this.stamp.incrementAndGet();
+        return this.balance.compareAndSet(current, current + funds, stamps[0], newStamp);
+    }
+
+    public boolean withdrawal(int funds) {
+        int[] stamps = new int[1];
+        int current = this.balance.get(stamps);
+        int newStamp = this.stamp.incrementAndGet();
+        return this.balance.compareAndSet(current, current - funds, stamps[0], newStamp);
+    }
+}

core-java-modules/core-java-concurrency-advanced-3/src/test/java/com/baeldung/atomicstampedreference/ThreadSafeAccountUnitTest.java

@@ -0,0 +1,21 @@
+package com.baeldung.atomicstampedreference;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class ThreadSafeAccountUnitTest {
+
+    @Test
+    public void givenMultiThread_whenSafeAccount_thenSetBalance() throws InterruptedException {
+        SafeAccount account = new SafeAccount();
+        Thread t = new Thread(() -> {
+            while (!account.withdrawal(100))
+                Thread.yield();
+        });
+        t.start();
+        Assert.assertTrue(account.deposit(100));
+        t.join(1_000);
+        Assert.assertFalse(t.isAlive());
+        Assert.assertSame(0, account.getBalance());
+    }
+}