Simulated Annnealing fixes (#907)

* @Async and Spring Security

* @Async with SecurityContext propagated

* Spring and @Async

* Simulated Annealing algorithm

* Simulated Annealing algorithm

* Rebase

* Rebase

core-java/README.md

@@ -45,3 +45,4 @@
 - [Getting Started with Java Properties](http://www.baeldung.com/java-properties)
 - [Grep in Java](http://www.baeldung.com/grep-in-java)
 - [Java - Combine Multiple Collections](http://www.baeldung.com/java-combine-multiple-collections)
+- [Simulated Annealing for Travelling Salesman Problem](http://www.baeldung.com/java-simulated-annealing-for-traveling-salesman)

core-java/src/main/java/com/baeldung/algorithms/SimulatedAnnealing.java

@@ -25,6 +25,8 @@ public class SimulatedAnnealing {
                     currentSolution.revertSwap();
                 }
                 t *= coolingRate;
+            } else {
+            	continue;
             }
             if (i % 100 == 0) {
                 System.out.println("Iteration #" + i);
@@ -34,7 +36,7 @@ public class SimulatedAnnealing {
     }
 
     public static void main(String[] args) {
-        System.out.println("Optimized distance for travel: " + simulateAnnealing(10, 10000, 0.9));
+        System.out.println("Optimized distance for travel: " + simulateAnnealing(10, 10000, 0.9995));
     }
 
 }

core-java/src/main/java/com/baeldung/algorithms/Travel.java

@@ -27,7 +27,10 @@ public class Travel {
         int a = generateRandomIndex();
         int b = generateRandomIndex();
         previousTravel = travel;
-        travel.set(a, travel.get(b));
+        City x = travel.get(a);
+        City y = travel.get(b);
+        travel.set(a, y);
+        travel.set(b, x);
     }
 
     public void revertSwap() {