initial commit for BAEL-5185 (#11484)

* initial commit for BAEL-5185

* fixed issues

* fixed issues

* Added Junit test case

Co-authored-by: Vartika_Nigam <Vartika_Nigam@dellteam.com>

core-java-modules/core-java-concurrency-advanced-4/src/main/java/com/baeldung/volatilekeywordthreadsafety/VolatileVarNotThreadSafe.java

@@ -0,0 +1,47 @@
+package com.baeldung.volatilekeywordthreadsafety;
+
+import org.slf4j.LoggerFactory;
+import org.slf4j.Logger;
+
+public class VolatileVarNotThreadSafe {
+
+    private static final Logger LOG = LoggerFactory.getLogger(VolatileVarNotThreadSafe.class);
+    private static volatile int count = 0;
+    private static final int MAX_LIMIT = 1000;
+    
+    public static void increment() {
+        count++;
+    }
+    
+    public static int getCount() {
+        return count;
+    }
+    
+    public static void main(String[] args) throws InterruptedException {
+        Thread t1 = new Thread(new Runnable() {
+           @Override
+           public void run() {
+               for(int index=0; index<MAX_LIMIT; index++) {
+                   increment();
+               }
+           }
+        });
+        
+        Thread t2 = new Thread(new Runnable() {
+           @Override
+           public void run() {
+               for(int index=0; index<MAX_LIMIT; index++) {
+                   increment();
+               }
+           }
+        });
+        
+        t1.start();
+        t2.start();
+        
+        t1.join();
+        t2.join();
+        
+        LOG.info("value of counter variable: "+count);
+    }
+}

core-java-modules/core-java-concurrency-advanced-4/src/test/java/com/baeldung/volatilekeywordthreadsafety/VolatileVarNotThreadSafeUnitTest.java

@@ -0,0 +1,13 @@
+package com.baeldung.volatilekeywordthreadsafety;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class VolatileVarNotThreadSafeUnitTest {
+
+    @Test
+    public void whenCalledMainMethod_thenIncrementCount() throws InterruptedException {
+        VolatileVarNotThreadSafe.main(null);
+        Assertions.assertTrue(VolatileVarNotThreadSafe.getCount() > 0);
+    }
+}