How to Modify a javax.json.JsonObject Object?

Question

I am coding a feature in which I read and write back json. However I can read the json elements from a file but can't edit the same loaded object. Here is my code which I am working on.

InputStream inp = new FileInputStream(jsonFilePath);
JsonReader reader = Json.createReader(inp);

JsonArray employeesArr = reader.readArray();
for (int i = 0; i < 2; i++) {
    JsonObject jObj = employeesArr.getJsonObject(i);
    JsonObject teammanager = jObj.getJsonObject("manager");

    Employee manager = new Employee();
    manager.name = teammanager.getString("name");
    manager.emailAddress = teammanager.getString("email");
    System.out.println("uploading File " + listOfFiles[i].getName());
    File file  = insertFile(...);
    JsonObject tmpJsonValue = Json.createObjectBuilder()
        .add("fileId", file.getId())
        .add("alternativeLink", file.getAlternateLink())
        .build();

    jObj.put("alternativeLink", tmpJsonValue.get("alternativeLink"));  <-- fails here 
}

I get the following exception when I run it.

Exception in thread "main" java.lang.UnsupportedOperationException

at java.util.AbstractMap.put(AbstractMap.java:203)

at com.mongodb.okr.DriveQuickstart.uploadAllFiles(DriveQuickstart.java:196)

at com.mongodb.okr.App.main(App.java:28)

Answer 1

The javadoc of JsonObject states

JsonObject class represents an immutable JSON object value (an unordered collection of zero or more name/value pairs). It also provides unmodifiable map view to the JSON object name/value mappings.

You can't modify these objects.

You'll need to create a copy. There doesn't seem to be a direct way to do that. It looks like you'll need to use Json.createObjectBuilder() and build it yourself (see the example in the javadoc linked).

Answer 2

As answered by Sotirios, you can use JsonObjectBuilders. To insert value into JsonObject, you can use method:

private JsonObject insertValue(JsonObject source, String key, String value) {
    JsonObjectBuilder builder = Json.createObjectBuilder();
    builder.add(key, value);
    source.entrySet().
            forEach(e -> builder.add(e.getKey(), e.getValue()));
    return builder.build();
}

To insert JsonObject into JsonObject, you can use method:

private JsonObject insertObject(JsonObject parent, JsonObject child, String childName) {
    JsonObjectBuilder child_builder = Json.createObjectBuilder();
    JsonObjectBuilder parent_builder = Json.createObjectBuilder();
    parent.entrySet().
            forEach(e -> parent_builder.add(e.getKey(), e.getValue()));
    child.entrySet().
            forEach(e -> child_builder.add(e.getKey(), e.getValue()));
    parent_builder.add(childName, child_builder);
    return parent_builder.build();
}

Please note, if you change the child JsonObject after inserting it into another "parent" JsonObject, it will have no effect on the "parent" JsonObject.