- removed returning JSON string from toString methods of POJOs

- moved the code to get the `ObjectMapper` instance to `Utils` so that any changes to ObjectMapper could be handled at one place.
- removed duplicate ObjectMapper instantiation code

src/main/java/io/github/amithkoujalgi/ollama4j/core/OllamaAPI.java

@@ -1,9 +1,8 @@
 package io.github.amithkoujalgi.ollama4j.core;
 
-import com.fasterxml.jackson.databind.DeserializationFeature;
-import com.fasterxml.jackson.databind.ObjectMapper;
 import io.github.amithkoujalgi.ollama4j.core.exceptions.OllamaBaseException;
 import io.github.amithkoujalgi.ollama4j.core.models.*;
+import io.github.amithkoujalgi.ollama4j.core.utils.Utils;
 import org.apache.hc.client5.http.classic.methods.HttpDelete;
 import org.apache.hc.client5.http.classic.methods.HttpGet;
 import org.apache.hc.client5.http.classic.methods.HttpPost;
@@ -37,9 +36,6 @@ public class OllamaAPI {
     private final String host;
     private boolean verbose = false;
 
-    private final ObjectMapper objectMapper = new ObjectMapper()
-            .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
-
     /**
      * Instantiates the Ollama API.
      *
@@ -82,7 +78,7 @@ public class OllamaAPI {
                 responseString = EntityUtils.toString(responseEntity, "UTF-8");
             }
             if (statusCode == 200) {
-                return objectMapper.readValue(responseString, ListModelsResponse.class).getModels();
+                return Utils.getObjectMapper().readValue(responseString, ListModelsResponse.class).getModels();
             } else {
                 throw new OllamaBaseException(statusCode + " - " + responseString);
             }
@@ -114,7 +110,7 @@ public class OllamaAPI {
                 responseString = EntityUtils.toString(responseEntity, "UTF-8");
             }
             if (statusCode == 200) {
-                return objectMapper.readValue(responseString, ModelDetail.class);
+                return Utils.getObjectMapper().readValue(responseString, ModelDetail.class);
             } else {
                 throw new OllamaBaseException(statusCode + " - " + responseString);
             }
@@ -245,9 +241,9 @@ public class OllamaAPI {
         con.setRequestMethod("POST");
         con.setDoOutput(true);
         con.setRequestProperty("Content-Type", "application/json");
-        System.out.println(ollamaRequestModel.toString());
+        String jsonReq = Utils.getObjectMapper().writeValueAsString(ollamaRequestModel);
         try (OutputStream out = con.getOutputStream()) {
-            out.write(ollamaRequestModel.toString().getBytes(StandardCharsets.UTF_8));
+            out.write(jsonReq.getBytes(StandardCharsets.UTF_8));
         }
         int responseCode = con.getResponseCode();
         if (responseCode == HttpURLConnection.HTTP_OK) {
@@ -255,7 +251,7 @@ public class OllamaAPI {
                 String inputLine;
                 StringBuilder response = new StringBuilder();
                 while ((inputLine = in.readLine()) != null) {
-                    OllamaResponseModel ollamaResponseModel = objectMapper.readValue(inputLine, OllamaResponseModel.class);
+                    OllamaResponseModel ollamaResponseModel = Utils.getObjectMapper().readValue(inputLine, OllamaResponseModel.class);
                     if (!ollamaResponseModel.getDone()) {
                         response.append(ollamaResponseModel.getResponse());
                     }
@@ -284,8 +280,9 @@ public class OllamaAPI {
         con.setRequestMethod("POST");
         con.setDoOutput(true);
         con.setRequestProperty("Content-Type", "application/json");
+        String jsonReq = Utils.getObjectMapper().writeValueAsString(ollamaRequestModel);
         try (OutputStream out = con.getOutputStream()) {
-            out.write(ollamaRequestModel.toString().getBytes(StandardCharsets.UTF_8));
+            out.write(jsonReq.getBytes(StandardCharsets.UTF_8));
         }
         OllamaAsyncResultCallback ollamaAsyncResultCallback = new OllamaAsyncResultCallback(con);
         ollamaAsyncResultCallback.start();
@@ -316,7 +313,7 @@ public class OllamaAPI {
             String responseString = "";
             if (responseEntity != null) {
                 responseString = EntityUtils.toString(responseEntity, "UTF-8");
-                EmbeddingResponse embeddingResponse = objectMapper.readValue(responseString, EmbeddingResponse.class);
+                EmbeddingResponse embeddingResponse = Utils.getObjectMapper().readValue(responseString, EmbeddingResponse.class);
                 return embeddingResponse.getEmbedding();
             } else {
                 throw new OllamaBaseException(statusCode + " - " + responseString);

src/main/java/io/github/amithkoujalgi/ollama4j/core/models/ModelDetail.java

@@ -1,8 +1,6 @@
 package io.github.amithkoujalgi.ollama4j.core.models;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.ObjectMapper;
 
 public class ModelDetail {
     private String license;
@@ -41,16 +39,4 @@ public class ModelDetail {
     public void setTemplate(String template) {
         this.template = template;
     }
-
-    @Override
-    public String toString() {
-        try {
-            return new ObjectMapper()
-                    .writer()
-                    .withDefaultPrettyPrinter()
-                    .writeValueAsString(this);
-        } catch (JsonProcessingException e) {
-            throw new RuntimeException(e);
-        }
-    }
 }

src/main/java/io/github/amithkoujalgi/ollama4j/core/models/OllamaAsyncResultCallback.java

@@ -1,7 +1,7 @@
 package io.github.amithkoujalgi.ollama4j.core.models;
 
-import com.fasterxml.jackson.databind.ObjectMapper;
 import io.github.amithkoujalgi.ollama4j.core.exceptions.OllamaBaseException;
+import io.github.amithkoujalgi.ollama4j.core.utils.Utils;
 
 import java.io.BufferedReader;
 import java.io.IOException;
@@ -10,12 +10,12 @@ import java.net.HttpURLConnection;
 import java.util.LinkedList;
 import java.util.Queue;
 
+
 @SuppressWarnings("DuplicatedCode")
 public class OllamaAsyncResultCallback extends Thread {
     private final HttpURLConnection connection;
     private String result;
     private boolean isDone;
-    private final ObjectMapper objectMapper = new ObjectMapper();
     private final Queue<String> queue = new LinkedList<>();
 
     public OllamaAsyncResultCallback(HttpURLConnection connection) {
@@ -35,7 +35,7 @@ public class OllamaAsyncResultCallback extends Thread {
                     String inputLine;
                     StringBuilder response = new StringBuilder();
                     while ((inputLine = in.readLine()) != null) {
-                        OllamaResponseModel ollamaResponseModel = objectMapper.readValue(inputLine, OllamaResponseModel.class);
+                        OllamaResponseModel ollamaResponseModel = Utils.getObjectMapper().readValue(inputLine, OllamaResponseModel.class);
                         queue.add(ollamaResponseModel.getResponse());
                         if (!ollamaResponseModel.getDone()) {
                             response.append(ollamaResponseModel.getResponse());

src/main/java/io/github/amithkoujalgi/ollama4j/core/models/OllamaRequestModel.java

@@ -1,9 +1,6 @@
 package io.github.amithkoujalgi.ollama4j.core.models;
 
 
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.ObjectMapper;
-
 public class OllamaRequestModel {
     private String model;
     private String prompt;
@@ -28,16 +25,4 @@ public class OllamaRequestModel {
     public void setPrompt(String prompt) {
         this.prompt = prompt;
     }
-
-    @Override
-    public String toString() {
-        try {
-            return new ObjectMapper()
-                    .writer()
-                    .withDefaultPrettyPrinter()
-                    .writeValueAsString(this);
-        } catch (JsonProcessingException e) {
-            throw new RuntimeException(e);
-        }
-    }
 }

src/main/java/io/github/amithkoujalgi/ollama4j/core/utils/Utils.java

@@ -0,0 +1,9 @@
+package io.github.amithkoujalgi.ollama4j.core.utils;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class Utils {
+    public static ObjectMapper getObjectMapper() {
+        return new ObjectMapper();
+    }
+}