JSON File - Java: editing/updating fields values
<p>I have some JSONObject(s) in my workflow, and the same JSONObjects are stored by writting them into a json file.</p>

<p>I would like an efficient way to update the json file, <strong>only fields where is needed</strong>, with the content of newer JSONObjects instances.</p>

<p>Eg:</p>

<p>On file I have</p>

<pre><code>ObjectOnFile = {key1:val1, key2:val2,...}
</code></pre>

<p>In memory I have </p>

<pre><code>ObjectInMemory = {key1:val1_newer, key2:val2_newer,...}
</code></pre>

<p>The update will be like: </p>

<pre><code> if (!(ObjectInMemory.get(key1).equals(ObjectOnFile.get(key1)))
       // update file field value &lt;--- how to?
</code></pre>

<p>In general I would like to update the value of every key where its content is newer (different).</p>

<p>Actually my code is:</p>

<pre><code>import org.json.JSONObject;
import com.fasterxml.jackson.databind.ObjectMapper;

ObjectMapper mapper = new ObjectMapper();
Sting key = "key1"; //whatever
JSONObject jo = new JSONObject("{key1:\"val1\", key2:\"val2\"}");
JSONObject root = mapper.readValue(new File(json_file), JSONObject.class);
JSONObject val_newer = jo.getJSONObject(key);
JSONObject val_older = root.getJSObject(key);
if(!val_newer.equals(val_older)){
   root.put(key,val_newer);
/*write back root to the json file...how? */
}
</code></pre>