Jackson: Read json from a file and map to an object

ObjectMapper class provides 'readValue' method, which can read the json content from a file and convert it to the object.

 

Signature

public <T> T readValue(File src, Class<T> valueType)

 

Example

ObjectMapper objectMapper = new ObjectMapper();
String filePath = "/Users/Shared/examples/emp.json";
HashMap<?, ?> map = objectMapper.readValue(new File(filePath), HashMap.class);

 

 

Find the below working application.

 

emp.json

{
	"id": 1,
	"firstName": "Krishna",
	"lastName": "Gurram"
}

ReadJsonFromFile.java

package com.sample.app;

import java.io.File;
import java.io.IOException;
import java.util.HashMap;

import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;

public class ReadJsonFromFile {
	
	public static void main(String[] args) throws JsonParseException, JsonMappingException, IOException {
		ObjectMapper objectMapper = new ObjectMapper();
		String filePath = "/Users/Shared/examples/emp.json";
		
		
		HashMap<?, ?> map = objectMapper.readValue(new File(filePath), HashMap.class);
		System.out.println(map);
		
	}

}

Output

{firstName=Krishna, lastName=Gurram, id=1}

 

 

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