Enable serializable for the problems

README.md

@@ -19,7 +19,7 @@ Add the follow dependency to your POM file:
 <dependency>
   <groupId>com.github.chen0040</groupId>
   <artifactId>java-moea</artifactId>
-  <version>1.0.4</version>
+  <version>1.0.5</version>
 </dependency>
 ```
 

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>com.github.chen0040</groupId>
     <artifactId>java-moea</artifactId>
-    <version>1.0.5</version>
+    <version>1.0.6</version>
 
 
     <licenses>

src/main/java/com/github/chen0040/moea/problems/NDND.java

@@ -11,6 +11,9 @@
  * Created by xschen on 17/6/2017.
  */
 public class NDND implements ProblemInstance {
+   private static final long serialVersionUID = 8627945754278982189L;
+
+
    @Override public double getCost(Solution x, int objective_index) {
 
       double f1 = 1 - Math.exp((-4) * x.get(0)) * Math.pow(Math.sin(5 * Math.PI * x.get(0)), 4);

src/main/java/com/github/chen0040/moea/problems/NGPD.java

@@ -13,6 +13,8 @@
 public class NGPD implements ProblemInstance {
 
    private final static double M = 888888.0;
+   private static final long serialVersionUID = -8997395531572954837L;
+
 
    @Override public double getCost(Solution x, int objective_index) {
       if(objective_index==0)

src/main/java/com/github/chen0040/moea/problems/OKA2.java

@@ -11,6 +11,9 @@
  * Created by xschen on 17/6/2017.
  */
 public class OKA2 implements ProblemInstance {
+   private static final long serialVersionUID = 6665004120372165596L;
+
+
    @Override public double getCost(Solution x, int objective_index) {
       double f=0;
       switch(objective_index)

src/main/java/com/github/chen0040/moea/problems/ProblemInstance.java

@@ -3,13 +3,14 @@
 
 import com.github.chen0040.moea.components.Solution;
 
+import java.io.Serializable;
 import java.util.List;
 
 
 /**
  * Created by xschen on 17/6/2017.
  */
-public interface ProblemInstance {
+public interface ProblemInstance extends Serializable {
    double getCost(Solution x, int objective_index);
 
 

src/main/java/com/github/chen0040/moea/problems/SYMPART.java

@@ -16,6 +16,7 @@ public class SYMPART implements ProblemInstance {
    private final static double a = 1;
    private final static double b = 10;
    private final static double c = 8;
+   private static final long serialVersionUID = -1412323130109052886L;
    private double c1;
    private double c2;
    private double b1;

src/main/java/com/github/chen0040/moea/problems/TNK.java

@@ -13,6 +13,8 @@
 public class TNK implements ProblemInstance {
 
    public static final double M = 888888.0;
+   private static final long serialVersionUID = -1673652070484478816L;
+
 
    @Override
    public double getCost(Solution x, int objective_index)