Convert Java Object to Map

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Scenario

Need to convert a simple java object having some attributes or properties and need to convert its values into a Map.

Solution

There are many solutions but the easiest solution (and my personal preference) is by using the Jackson library dependency.

Use this dependency in your pom.xml file

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.15.0</version>
</dependency>

Lets define a class to which will be converted into the Map.

Java Class — Employee Class

class Employee { 
  String name;
  Integer age;
  List<String> skills;

  // getter setter methods
}

Now you can write a function to convert the java object into a Map.

import java.util.Arrays;
import java.util.Map;

import com.fasterxml.jackson.databind.ObjectMapper;

public class FooBar { 
  
  public static convertObjectToMap(Employee employee) { 
    ObjectMapper mapper = new ObjectMapper();
    Map<String, Object> map= mapper.convertValue(employee, Employee.class);
    return map;
  }
}

Example

class Main {
  public static void main(String[] args){
    Employee emp = new Employee();
    emp.setName("ABC");
    emp.setAge(30);
    emp.setSkillts(Arrays.asList("hello", "there"));
    
    // object --> map
    Map<String, Object> objectMap = FooBar.convertObjectToMap(emp);
    System.out.println(obejctMap);
  }
}

Output

{
  name : "ABC",
  age : 30,
  skills : [
    "hello",
    "there"
  ]
}

Bonus

You can create a generic function which can convert any object to a map

public static convertObjectToMap(T object) { 
  ObjectMapper mapper = new ObjectMapper();
  Map<String, Object> map= mapper.convertValue(object, T.class);
  return map;
}

Now you can reuse this function to convert any object into a map.

References

Stack Overflow