If you are aware of Jackson 2, there is a great tutorial at mkyong.com on how to convert Java Objects to JSON and vice versa. The following code snippets have been taken from that tutorial.
Convert Java object to JSON, writeValue(...):
ObjectMapper mapper = new ObjectMapper();
Staff obj = new Staff();
//Object to JSON in file
mapper.writeValue(new File("c:\\file.json"), obj);
//Object to JSON in String
String jsonInString = mapper.writeValueAsString(obj);
Convert JSON to Java object, readValue(...):
ObjectMapper mapper = new ObjectMapper();
String jsonInString = "{'name' : 'mkyong'}";
//JSON from file to Object
Staff obj = mapper.readValue(new File("c:\\file.json"), Staff.class);
//JSON from URL to Object
Staff obj = mapper.readValue(new URL("http://mkyong.com/api/staff.json"), Staff.class);
//JSON from String to Object
Staff obj = mapper.readValue(jsonInString, Staff.class);
Jackson 2 Dependency:
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.6.3</version>
</dependency>
For the full tutorial, please go to the link given above.