add gson support

Author: Ruinan Zhang

smoothnlp_maven/pom.xml

@@ -45,6 +45,11 @@
             <version>0.82</version>
         </dependency>
 
+        <dependency>
+            <groupId>com.google.code.gson</groupId>
+            <artifactId>gson</artifactId>
+            <version>2.8.5</version>
+        </dependency>
 
     </dependencies>
 

smoothnlp_maven/smoothnlp.iml

@@ -29,5 +29,6 @@
     <orderEntry type="library" name="Maven: ml.dmlc:xgboost4j:0.82" level="project" />
     <orderEntry type="library" name="Maven: com.typesafe.akka:akka-actor_2.11:2.3.11" level="project" />
     <orderEntry type="library" name="Maven: com.typesafe:config:1.2.1" level="project" />
+    <orderEntry type="library" name="Maven: com.google.code.gson:gson:2.8.5" level="project" />
   </component>
 </module>

smoothnlp_maven/src/main/java/com/smoothnlp/nlp/basic/UtilFns.java

@@ -1,6 +1,8 @@
 package com.smoothnlp.nlp.basic;
 
 import java.util.Arrays;
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
 
 public class UtilFns {
 
@@ -41,4 +43,13 @@ public static float[] flatten2dFloatArray(float[][] f2darray){
         return output;
     }
 
+
+    public static String toJson(Object o){
+        GsonBuilder gb = new GsonBuilder();
+        gb = gb.serializeSpecialFloatingPointValues();
+        gb = gb.serializeNulls();
+        Gson gson = gb.create();
+        return gson.toJson(o);
+    }
+
 }