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  1. PO
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    <p>The simplest solution which I can imagine - is deserializing your JSON into <code>Map</code> class (for example LinkedHashMap). Please, see my below example:</p> <pre><code>import java.util.LinkedHashMap; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonProgram { public static void main(String[] args) throws Exception { ObjectMapper mapper = new ObjectMapper(); String json = "{\"a\":\"java.lang.Integer\",\"b\":\"time json\",\"c\":\"action json\",\"d\":[1,2,3]}"; System.out.println(json); LinkedHashMap&lt;String, Object&gt; map = mapper.readValue(json, LinkedHashMap.class); map.put("b", "Override property or create new"); System.out.println(mapper.writeValueAsString(map)); } } </code></pre> <p>Above program prints:</p> <pre><code>{"a":"java.lang.Integer","b":"time json","c":"action json","d":[1,2,3]} {"a":"java.lang.Integer","b":"Override property or create new","c":"action json","d":[1,2,3]} </code></pre> <p>If you want to change inner property on the path you can implement it in this way:</p> <pre><code>import java.io.IOException; import java.util.Arrays; import java.util.Collection; import java.util.LinkedHashMap; import java.util.LinkedList; import com.fasterxml.jackson.databind.ObjectMapper; public class JacksonProgram { public static void main(String[] args) throws IOException { ObjectMapper mapper = new ObjectMapper(); String json = "{\"b\":{\"bb\":{\"bbb\":20}}}"; System.out.println(json); LinkedHashMap&lt;String, Object&gt; map = mapper.readValue(json, LinkedHashMap.class); JsonUpdater updater = new JsonUpdater(map); updater.update(Arrays.asList("b", "bb", "bbb"), 4); System.out.println(mapper.writeValueAsString(map)); } } class JsonUpdater { private LinkedHashMap&lt;String, Object&gt; jsonMap; public JsonUpdater(LinkedHashMap&lt;String, Object&gt; jsonMap) { this.jsonMap = jsonMap; } public boolean update(Collection&lt;String&gt; propertiesOnThePath, Object newValue) { LinkedList&lt;String&gt; path = new LinkedList&lt;String&gt;(propertiesOnThePath); String lastProperty = path.removeLast(); LinkedHashMap&lt;String, Object&gt; objectMap = jsonMap; while (!path.isEmpty()) { String property = path.poll(); if (!objectMap.containsKey(property)) { return false; } objectMap = (LinkedHashMap&lt;String, Object&gt;) objectMap.get(property); } if (!objectMap.containsKey(lastProperty)) { return false; } objectMap.put(lastProperty, newValue); return false; } } </code></pre> <p>Above program prints:</p> <pre><code>{"b":{"bb":{"bbb":20}}} {"b":{"bb":{"bbb":4}}} </code></pre> <p>As we can see: value was changed. But this solution has huge disadvantage - we have to deserialize all JSON. Few thousands bytes String is not a problem for Java, but if you really want to optimaze your program you can play with <code>ObjectNode</code> class and <code>ObjectMapper#readTree</code> method. Please see below source code:</p> <pre><code>import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.node.ObjectNode; public class JacksonProgram { public static void main(String[] args) throws Exception { ObjectMapper mapper = new ObjectMapper(); String json = "{\"a\":\"java.lang.Integer\",\"b\":\"time json\",\"c\":\"action json\",\"d\":[1,2,3]}"; System.out.println(json); ObjectNode jsonTree = (ObjectNode) mapper.readTree(json); jsonTree.put("b", "Override property or create new"); System.out.println(jsonTree.toString()); } } </code></pre> <p>Above program prints:</p> <pre><code>{"a":"java.lang.Integer","b":"time json","c":"action json","d":[1,2,3]} {"a":"java.lang.Integer","b":"Override property or create new","c":"action json","d":[1,2,3]} </code></pre> <p>I didn't do any comparison tests, but you can test which solution works faster for you.</p>
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    1. POJackson API: partially update a string
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    1. USMichał Ziober
    1. USMichał Ziober
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      1. VTUpMod
    1. COMaybe I did not understand your question. I thought you want to change incoming JSON and return changed version. Let me know how can I improve my answer.
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      1. PO
      1. USMichał Ziober
    2. COYour answer gave me a few ideas ... but this is not quite what I need. Indeed, what my JsonObject example hides is that I want to update an object and not just 1 value. If I reuse your notations, I want to be able to do: jsonTree.put("b", instanceOfObjectB); where ObjectB is a Java object jackson would have auto deserialized its @JsonProperty annotations... (putPojo doesn't help) After many tries, ... I think I have a solution involving a custom module and bean serializer. I'll post a full example if it works. In the meantime, if you/someone think of an easier approach...
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      1. USfabien
 

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