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One of the common uses case is to work with Json and use or convert it as java object.

Add the Jackson dependency in pom.xml file

<repositories>
	<repository>
		<id>codehaus</id>
		<url>http://repository.codehaus.org/org/codehaus</url>
	</repository>
  </repositories>
 
  <dependencies>
	<dependency>
		<groupId>org.codehaus.jackson</groupId>
		<artifactId>jackson-mapper-asl</artifactId>
		<version>1.9.12</version>
	</dependency>
  </dependencies>

The Java class :

public static void main(String args[]) {
        ObjectMapper mapper = new ObjectMapper();
        Map m = new HashMap();
        Map personMap = new HashMap<>();
        Map personDetail = new HashMap();
        personDetail.put("firstname", "Bob");
        personDetail.put("lastname", "jackson");
        personDetail.put("age", "12");
        personDetail.put("city", "Berlin");
        
        personMap.put("person", personDetail);
        //convert Map to json string
        try {
            System.out.println(mapper.writeValueAsString(personMap));
        } catch (IOException e) {
            e.printStackTrace();
        }

        // convert json to Map 
        String json = "{\"person\":{\"age\":\"12\",\"lastname\":\"jackson\""
                + ",\"firstname\":\"Bob\",\"city\":\"Berlin\"}}"
        try {
            Map map = mapper.readValue(json, Map.class);
            System.out.println("Map is " + map);
        } catch (Exception e) {
            e.printStackTrace();
        }
 }

Output is

{“person”:{“age”:”12″,”lastname”:”jackson”,”firstname”:”Bob”,”city”:”Berlin”}}
Map is {person={age=12, lastname=jackson, firstname=Bob, city=Berlin}}

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