Write / Read / Parse / Pretty Print JSON using Jackson FasterXML

Jackson provide writeValue() and readValue() methods to convert Java objects to / from JSON.

mapper.writeValue – Java Objects to JSON

ObjectMapper mapper = new ObjectMapper();

// Write Java object to JSON file
mapper.writeValue(new File("c:\\test\\staff.json"), new Staff());

// Encode Java object to JSON string, default compact-print
String jsonString = mapper.writeValueAsString(new Staff());
 
// Encode Java object to JSON string with Pretty Print
String jsonPrettyString = mapper.writerWithDefaultPrettyPrinter().writeValueAsString(new Staff());

mapper.readValue – JSON to Java Objects

 ObjectMapper mapper = new ObjectMapper();

 //JSON file to Java object
 Staff obj = mapper.readValue(new File("c:\\test\\staff.json"), Staff.class);

 //JSON URL to Java object
 Staff obj = mapper.readValue(new URL("http://some-domains/api/staff.json"), Staff.class);

 //JSON string to Java Object
 Staff obj = mapper.readValue("{'name' : 'mkyong'}", Staff.class);


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Declares jackson-databind, it will pull in jackson-annotations and jackson-core

pom.xml

 <dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.9.8</version>
 </dependency>

Reference:

• Jackson data-binding official website
• Jackson 2 – Convert Java Object to / from JSON
• Gson – How to parse JSON