[BAEL 717]-Singleton Session Bean. (#4001)

* BAEL-717: Singleton EJB Bean

Files for BAEL-717:Singleton EJB Bean.

* BAEL-717: Singleton EJB Bean

Corrected Indentation.

* BAEL-717: Singleton EJB Bean

Corrected Indentation.

* BAEL-717: Singleton EJB Bean

Corrected Indentation.

* BAEL-717: Singleton EJB Bean

Corrected Indentation.

* BAEL-717: Singleton EJB Bean

Changed artifactId value.

* BAEL-717: Singleton EJB Bean.

Added module for Singleton EJB Bean.

* BAEL-717: Singleton EJB Bean. 

Removed Singleton EJB Bean Module.

* BAEL-717: Singleton EJB Bean

Changed the JNDI Lookup name.

* BAEL-717: Singleton EJB Bean. 

Added the "singleton-ejb-bean" module.

* BAEL-717: Singleton EJB Bean.

Corrected Indentation.

* BAEL-717: Singleton EJB Bean

Corrected Indentation.

* BAEL-717: Singleton EJB Bean.

Corrected Indentation.

* BAEL-717: Singleton EJB Bean.

Corrected Indentation.

* BAEL-717:Singleton EJB Bean.

Corrected Indentation.

* BAEL-717:Singleton EJB Bean.

Corrected Indentation.

* BAEL-717: Singleton Session Bean.

Added class for Bean-Managed concurrrency.
Changed class name from CountryStateCacheBean to CountryStateContainerManagedBean.

* BAEL-717: Singleton Session Bean.

Changing the name of the class to CountryStateContainerManagedBean.

* BAEL-717: Singleton Session Bean.

Added method to test Bean-Managed concurrency.

* Get Latest.

* deleting CountryStateBeanManagedBean for new file.

* deleting CountryStateCacheBean for new file.

* deleting CountryStateContainerManagedBean for new file.

* BAEL-717: Singleton Session Bean.

Adding file for Bean with Bean-Managed concurrency.
Changing file name for original file to CountryStateContainerManagedBean with Container-Managed concurrency.

* Deleting file for new checkin.

* BAEL-717: Singleton Session Bean.

Added test case for Bean-Manged concurrency.
Change in JNDI names.

* BAEL-717: Singleton Session Bean.

Changed the assert method parameter order and null check in test cases.

spring-ejb/singleton-ejb-bean/src/main/java/com/baeldung/singletonbean/CountryStateBeanManagedBean.java

@@ -0,0 +1,39 @@
+package com.baeldung.singletonbean;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import javax.annotation.PostConstruct;
+import javax.ejb.ConcurrencyManagement;
+import javax.ejb.ConcurrencyManagementType;
+import javax.ejb.Lock;
+import javax.ejb.LockType;
+import javax.ejb.Singleton;
+import javax.ejb.Startup;
+
+@Singleton
+@Startup
+@ConcurrencyManagement(ConcurrencyManagementType.BEAN)
+public class CountryStateBeanManagedBean implements CountryState {
+
+    private volatile Map<String, List<String>> countryStatesMap = new HashMap<String, List<String>>();
+
+    @PostConstruct
+    public synchronized void initialize() {
+
+        List<String> states = new ArrayList<String>();
+        states.add("Texas");
+        states.add("Alabama");
+        states.add("Alaska");
+        states.add("Arizona");
+        states.add("Arkansas");
+
+        countryStatesMap.put("UnitedStates", states);
+    }
+
+    public List<String> getStates(String country) {
+        return countryStatesMap.get(country);
+    }
+}

spring-ejb/singleton-ejb-bean/src/main/java/com/baeldung/singletonbean/CountryStateContainerManagedBean.java

@@ -16,7 +16,7 @@ import javax.ejb.Startup;
 @Singleton
 @Startup
 @ConcurrencyManagement(ConcurrencyManagementType.CONTAINER)
-public class CountryStateCacheBean implements CountryState {
+public class CountryStateContainerManagedBean implements CountryState {
 
     private Map<String, List<String>> countryStatesMap = new HashMap<String, List<String>>();
 

spring-ejb/singleton-ejb-bean/src/test/java/com/baeldung/singletonbean/CountryStateCacheBeanTest.java

@@ -1,6 +1,7 @@
 package com.baeldung.singletonbean;
 
 import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertNotNull;
 
 import java.util.List;
 
@@ -11,8 +12,6 @@ import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 
-import com.baeldung.singletonbean.CountryState;
-
 public class CountryStateCacheBeanTest {
 
     private EJBContainer ejbContainer = null;
@@ -27,15 +26,25 @@ public class CountryStateCacheBeanTest {
     }
 
     @Test
-    public void whenCallGetStates_ReturnsStatesForCountry() throws Exception {
+    public void whenCallGetStatesFromContainerManagedBean_ReturnsStatesForCountry() throws Exception {
 
-        String[] actualStates = { "Texas", "Alabama", "Alaska", "Arizona", "Arkansas" };
+        String[] expectedStates = { "Texas", "Alabama", "Alaska", "Arizona", "Arkansas" };
 
-        CountryState countryStateBean = (CountryState) context.lookup("java:global/singleton-ejb-bean/CountryStateCacheBean");
-        List<String> states = countryStateBean.getStates("UnitedStates");
-        if (states != null) {
-            assertArrayEquals(states.toArray(), actualStates);
-        }
+        CountryState countryStateBean = (CountryState) context.lookup("java:global/singleton-ejb-bean/CountryStateContainerManagedBean");
+        List<String> actualStates = countryStateBean.getStates("UnitedStates");
+        assertNotNull(actualStates);
+        assertArrayEquals(expectedStates, actualStates.toArray());
+    }
+
+    @Test
+    public void whenCallGetStatesFromBeanManagedBean_ReturnsStatesForCountry() throws Exception {
+
+        String[] expectedStates = { "Texas", "Alabama", "Alaska", "Arizona", "Arkansas" };
+
+        CountryState countryStateBean = (CountryState) context.lookup("java:global/singleton-ejb-bean/CountryStateBeanManagedBean");
+        List<String> actualStates = countryStateBean.getStates("UnitedStates");
+        assertNotNull(actualStates);
+        assertArrayEquals(expectedStates, actualStates.toArray());
     }
 
     @After