Convert JSON to Map or Map to JSON using Jackson library in Java?

JSON Jackson is a Java library that has very powerful data binding functions and provides a way to serialize custom java objects to JSON and deserialize JSON Back to the framework of Java objects. We can convert JSON to/from MapUse the readValue() and writeValueAsString() methods of the com.fasterxml.jackson.databind.ObjectMapper class.

JSON to mapping

Syntax

public <T> T readValue(String content, TypeReference valueTypeRef) throws IOException, JsonParseException, JsonMappingException

Example

import java.io.*;
import java.util.*;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.core.type.TypeReference;
public class ConvertJSONToMapTest {
   public static void main(String args[]) {
      try {
        <strong> </strong>ObjectMapper mapper = new ObjectMapper();
         String jsonString = "{\"Name\":\"Raja\", \"Technology\":\"Java\"}";
         Map<String, Object> jsonMap = new HashMap<String, Object>();
         jsonMap = mapper.readValue(jsonString, new TypeReference<Map<String, String>>(){}); // converts JSON to Map
         System.out.println(jsonMap);
      } catch(IOException ie) {
         ie.printStackTrace();
      }
   }
}

Output

{Name=Raja, Technology=Java}

Map to JSON

Syntax

public String writeValueAsString(Object value) throws JsonProcessingException

Example

import java.io.*;
import java.util.*;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.ObjectMapper;
public class ConvertMapToJSONTest {
   public static void main(String args[]) throws IOException {
      ObjectMapper mapper = new ObjectMapper();
      String jsonString = "";
      Map<String, Object> map = new HashMap<String, Object>();
      map.put("Raja", "Java Technology");
      map.put("Ravi", "Python Technology");
      map.put("Adithya", "Spark Technology");
      map.put("Vamsi", "Web Technology");
      jsonString = mapper.writeValueAsString(map); // converts Map to JSON<strong>
 </strong>     System.out.println(map);
   }
}

Output

{"Raja":"Java Technology", "Vamsi":"Web Technology", "Ravi":"Python Technology", "Adithya":"Spark Technology"}

The above is the detailed content of Convert JSON to Map or Map to JSON using Jackson library in Java?. For more information, please follow other related articles on the PHP Chinese website!