How to Convert JSON to JAVA Object using ObjectMapper?

Question

Java Object

class B {
   private String attr;
/***** getters and setters *****/

} 

class A {
      private String attr1;
      private String attr2;
      private Map<String,B> attr3;

    /***** getters and setters *****/

}

Json Object

json = {attr1 :"val1", attr2 : "val2", attr3 : {attr : "val"}}

How to convert json to java Object (class java contain Map as type of attribute) ?

Please find the below to links https://stackoverflow.com/questions/17651395/convert-jsonobject-to-string https://stackoverflow.com/questions/33914690/putting-json-values-into-hashmap — Hasnain Ali Bohra, Nov 09 '17 at 08:24

score 2 · Answer 1 · answered Nov 09 '17 at 08:34

2

You can use Jackson to do that:

//Create mapper instance
ObjectMapper mapper = new ObjectMapper();

//Usea a JSON string (exists other methos, i.e. you can get the JSON from a file)
String jsonString= "{'name' : 'test'}";

//JSON from String to Object
MyClass result= mapper.readValue(jsonString, MyClass .class);

answered Nov 09 '17 at 08:34

canillas

414
3
13

1

Thank you for your answer, It not works when I tried to use Java Class contain a Map like the example above (class A) – Radhouan HRIZI Nov 09 '17 at 08:36

Khalid Abu El-Soud · Answer 2 · 2017-11-09T09:40:12.467

1

You can use Gson library as following:

// representation string for your Json object
String json = "{\"attr1\": \"val1\",\"attr2\": \"val2\",\"attr3\": {\"attr\": \"val\"}}"; 

Gson gson = new Gson();
A a = gson.fromJson(json, A.class);

edited Nov 09 '17 at 09:40

answered Nov 09 '17 at 09:15

Khalid Abu El-Soud

109
9

1

Did you check your answer? – Yegor Babarykin Nov 09 '17 at 09:16

score 0 · Answer 3 · answered Aug 02 '18 at 05:09

Create a model/POJO which resembles your json structure and then by putting json string in json file you can get java object by using below simple code by using JACKSON dependacy

ObjectMapper mapper = new ObjectMapper();
File inRulesFile = (new ClassPathResource(rulesFileName + ".json")).getFile();
List<Rule> rules = mapper.readValue(inRulesFile, new TypeReference<List<Rule>>() {
        });

skyho · Answer 4 · 2020-04-13T13:16:14.637

@RunWith(SpringRunner.class)
@SpringBootTest
class PostSaveServiceTest {

    private static final String PATH_TO_JSON = "classpath:json/post-save";

    private static final String EXTENSION_JSON = ".json";

    @Test
    void setData() {

        ObjectMapper objectMapper = new ObjectMapper();

        Post post = runParseJsonFile(objectMapper);

        System.out.println(post);

    }



    private Post runParseJsonFile(ObjectMapper objectMapper) {

        File pathToFileJson = getPathToFileJson(PATH_TO_JSON + EXTENSION_JSON);

        Post post = null;

        try {
            post = objectMapper.readValue(pathToFileJson, Post.class);
        } catch (IOException e) {

            System.out.println("File didn't found : " + e);
       }

        return post;
    }


        private File getPathToFileJson(String path) {

        File pathToJson = null;

        try {

            pathToJson = ResourceUtils.getFile(path);

        } catch (IOException e) {
            e.printStackTrace();
        }


        return pathToJson;
    }
}

How to Convert JSON to JAVA Object using ObjectMapper?

4 Answers4