How to Modify a javax.json.JsonObject Object?

问题:

I am coding a feature in which I read and write back json. However I can read the json elements from a file but cant 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) 

回答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).

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