json - How to deserialize a HttpEntity containing Array Lists from Rest API call to a Java Object?

Question

I am trying to deserialize ResponseEntity<> returned by a Rest API call to Java Objects and had been unsuccessful. Following is the POJO

    public class Application {
           private String name;
           private List<String> location;
    } 

Here is the Rest API call and deserializing

public List<Application> getApps(){
       List<Application> = new ArrayList<>();
       ResponseEntity<String> returnObject = oauthRestTemplate.exchange(url, HttpMethod.POST, httpEntity, 
           String.class);
       ObjectMapper objectMapper = new ObjectMapper();
       Response response = objectMapper.readValue(returnObject.getBody(),
           Response.class);
       apps = objectMapper.convertValue(
                    response.getItems(),
                    new TypeReference<List<Application>>() {
                    }
            );
       return apps;
}

Response Java Object is

    public class Response {
           private String code;
           private String message;
           private String Status;
           private List<T> items;
    }

Contents of return response (returnObject.getBody()) is

    <Response>
        <code>200</code>
        <message></message>
        <status>SUCCESSFUL</status>
        <items>
            <items>
                <name>App1</name>
                <location>
                    <location>location1</location>
                </location>
            </items>
            <items>
                <name>App2</name>
                <location>
                    <location>location1</location>
                </location>
            </items>
        </items>
    </Response>

It is difficult to understand why additional tags for List is being added to the JSON string. The deserializing is failing when it encounters location tag within location. Following are the error logs

    com.fasterxml.jackson.core.JsonParseException: Unexpected character ('<' (code 60)): expected a valid value (number, String, array, object, 'true', 'false' or 'null')
     at [Source: (String)"<PagedResponse><code>200</code><message/><status>SUCCESSFUL</status><items><items><name>App1</name><location>" line: 1, column: 2]

Can someone help me understand what am I doing wrong here?

UPDATE Modified the "ObjectMapper" to "XmlMapper" and received the below error.

    java.lang.IllegalArgumentException: Cannot deserialize instance of `java.util.ArrayList` out of START_OBJECT token
     at [Source: UNKNOWN; line: -1, column: -1] (through reference chain: java.util.ArrayList[0]->com.example.dto.Application["location"])
            at com.fasterxml.jackson.databind.ObjectMapper._convert(ObjectMapper.java:3750)
            at com.fasterxml.jackson.databind.ObjectMapper.convertValue(ObjectMapper.java:3678)

question from:https://stackoverflow.com/questions/66055867/how-to-deserialize-a-httpentity-containing-array-lists-from-rest-api-call-to-a-j

Answer 1

It looks like you are using a JSON parser to parse XML. It fails at the beginning: line: 1, column: 2