How to convert hashmap to JSON object in Java

Question

How to convert or cast hashmap to JSON object in Java, and again convert JSON object to JSON string?

Answer 1

You can convert Map to JSON using Jackson as follows:

Map map = new HashMap<>();
//You can convert any Object.
String[] value1 = new String[] { "value11", "value12", "value13" };
String[] value2 = new String[] { "value21", "value22", "value23" };
map.put("key1", value1);
map.put("key2", value2);
map.put("key3","string1");
map.put("key4","string2");

String json = new ObjectMapper().writeValueAsString(map);
System.out.println(json);

Maven Dependencies for Jackson :

    com.fasterxml.jackson.core
    jackson-core
    2.5.3
    compile



    com.fasterxml.jackson.core
    jackson-databind
    2.5.3
    compile

If you are using JSONObject library, you can convert map to JSON as follows:

Map map = new HashMap<>();
// Convert a map having list of values.
String[] value1 = new String[] { "value11", "value12", "value13" };
String[] value2 = new String[] { "value21", "value22", "value23" };
map.put("key1", value1);
map.put("key2", value2);

JSONObject json = new JSONObject(map);
System.out.println(json);

Maven Dependencies for JSONObject :

    org.json
    json
    20140107

Hope this will help. Happy coding.