Create Map to JSON using Jackson

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In this tutorial we are going to see how to create JSON from map and print json as string and also write json in file
1. Create project called JSONExample.
2. Create package called com.javatutorialscorner.jackson 
3. add jackson-mapper-asl-1.9.13.jar, jackson-core-asl-1.9.13.jar into build path.
4. Create java class called MapToJSONExample under com.javatutorialscorner.jackson
MapToJSONExample .java

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01.package com.javatutorialscorner.jackson;

02. 

03.import java.io.File;

04.import java.io.IOException;

05.import java.util.ArrayList;

06.import java.util.HashMap;

07.import java.util.List;

08.import java.util.Map;

09. 

10.import org.codehaus.jackson.JsonGenerationException;

11.import org.codehaus.jackson.map.JsonMappingException;

12.import org.codehaus.jackson.map.ObjectMapper;

13. 

14.public class MapToJSONExample {

15. 

16. /**

17.  * @param args

18.  */

19. public static void main(String[] args) {

20.  // TODO Auto-generated method stub

21. 

22.  ObjectMapper mapper = null;

23. 

24.  Map<String, Object> map = null;

25. 

26.  List<Object> tutorials = null;

27. 

28.  try {

29.   mapper = new ObjectMapper();

30.   map = new HashMap<String, Object>();

31.   map.put("name", "Java Tutorials Corner");

32.   map.put("rank", "1");

33. 

34.   tutorials = new ArrayList<Object>();

35.   tutorials.add("Java");

36.   tutorials.add("Servlet");

37.   tutorials.add("JSP");

38.   tutorials.add("Struts 1.x");

39.   tutorials.add("Struts 2.x");

40.   tutorials.add("Spring");

41.   tutorials.add("Hibernate");

42.   tutorials.add("Log4j");

43.   tutorials.add("JSON");

44.   tutorials.add("Web Services");

45.   tutorials.add("JSF");

46.   tutorials.add("Eclipse");

47.    

48.   map.put("tutorials", tutorials);

49.   String json = mapper.writeValueAsString(map);

50.   System.out.println(json);

51.    

52.   mapper.writeValue(new File("C:\\jtc\\javatutorialscorner.json"),

53.     map);

54.  } catch (JsonGenerationException e) {

55.   // TODO Auto-generated catch block

56.   e.printStackTrace();

57.  } catch (JsonMappingException e) {

58.   // TODO Auto-generated catch block

59.   e.printStackTrace();

60.  } catch (IOException e) {

61.   // TODO Auto-generated catch block

62.   e.printStackTrace();

63.  }

64. 

65. }

66. 

67.}

Now run the program see the following output in console and also file created at specified location with following content.

{"tutorials":["Java","Servlet","JSP","Struts 1.x","Struts 2.x","Spring","Hibernate","Log4j","JSON","Web Services","JSF","Eclipse"],"rank":"1","name":"Java Tutorials Corner"}

Jackson Java JSON 10/18/2013 08:16:00 pm