cleanup: improve JSON class code

src/main/java/uulm/teamname/marvelous/gamelibrary/json/JSON.java

@@ -3,54 +3,48 @@ package uulm.teamname.marvelous.gamelibrary.json;
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.InjectableValues;
 import com.fasterxml.jackson.databind.ObjectMapper;
-import jdk.jshell.spi.ExecutionControl;
+import uulm.teamname.marvelous.gamelibrary.config.CharacterConfig;
 import uulm.teamname.marvelous.gamelibrary.messages.BasicMessage;
 import uulm.teamname.marvelous.gamelibrary.messages.EventMessage;
-import uulm.teamname.marvelous.gamelibrary.config.CharacterConfig;
 
 /**
  * Class that contains JSON encoding and decoding. It is initiated with the Character configuration.
  */
 public class JSON {
 
-    private final ObjectMapper mapper;
+    private final ObjectMapper mapper = new ObjectMapper();
 
     public JSON (CharacterConfig config) {
-        this.mapper = new ObjectMapper();
-
         // add the config to the mappers InjectableValues, where it is later accessed by the EntityDeserializer
         this.mapper.setInjectableValues(new InjectableValues
                 .Std()
                 .addValue("CharacterConfig", config));
-
     }
 
-
     /** Deserializes an incoming network message into a {@link EventMessage}.
-     * @param input The JSON to deserialize.
-     * @return The parsed message.
+     * @param input The JSON to deserialize
+     * @return The parsed message or {@code null} if the deserialization failed
      */
     public EventMessage parse(String input) {
         EventMessage result = null;
         try {
-            result = mapper.readValue(input, EventMessage.class);
+            return mapper.readValue(input, EventMessage.class);
         } catch (JsonProcessingException e) {
             e.printStackTrace();
+            return null;
         }
-        return result;
     }
 
     /** Serializes a {@link EventMessage} into a JSON string.
-     * @param input The message to serialize.
-     * @return The message as JSON.
+     * @param input The message to serialize
+     * @return The message as JSON or {@code null} if the serialization failed
      */
-    public String stringify(BasicMessage input) throws ExecutionControl.NotImplementedException {
-        String result = null;
+    public String stringify(BasicMessage input) {
         try {
-            result = mapper.writeValueAsString(input);
+            return mapper.writeValueAsString(input);
         } catch (JsonProcessingException e) {
             e.printStackTrace();
+            return null;
         }
-        return result;
     }
 }