Maven dependencies

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
            <version>2.10.0</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.8.11.1</version>
        </dependency>

Convert Object to Json

Core Logic

package jsondemo;

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

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class JavaToJSONExample {
    public static void main(String[] args) {
        List<City> cityList = new ArrayList<>();
        cityList.add(new City("LA","CA"));
        cityList.add(new City("NY","NY"));
        @SuppressWarnings("deprecation")
        Employee employee = new Employee(1, "Andrew Programming", new long[]{1234123, 4123123}, new Address("california"), cityList, "Manager", false);

        ObjectMapper mapper = new ObjectMapper();
        try {
            mapper.writeValue(new File("employee.json"), employee);
        } catch (JsonGenerationException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Employee.java

package jsondemo;

import java.util.Arrays;
import java.util.List;

public class Employee {
    private int id;
    private String name;
    private long[] number;
    private Address address;
    private List<City> cityList;
    private String Role;
    private boolean contractor;

    public Employee() {
    }

    public Employee(int id, String name, long[] number, Address address, List<City> cityList, String role, boolean contractor) {
        this.id = id;
        this.name = name;
        this.number = number;
        this.address = address;
        this.cityList = cityList;
        Role = role;
        this.contractor = contractor;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public long[] getNumber() {
        return number;
    }

    public void setNumber(long[] number) {
        this.number = number;
    }

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

    public List<City> getCityList() {
        return cityList;
    }

    public void setCityList(List<City> cityList) {
        this.cityList = cityList;
    }

    public String getRole() {
        return Role;
    }

    public void setRole(String role) {
        Role = role;
    }

    public boolean isContractor() {
        return contractor;
    }

    public void setContractor(boolean contractor) {
        this.contractor = contractor;
    }

    @Override
    public String toString() {
        return "Employee{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", number=" + Arrays.toString(number) +
                ", address=" + address +
                ", cityList=" + cityList +
                ", Role='" + Role + '\'' +
                ", contractor=" + contractor +
                '}';
    }
}

Address.java

package jsondemo;

public class Address {
    public Address() {
    }

    public Address(String location) {
        this.location = location;
    }

    private String location;

    public String getLocation() {
        return location;
    }

    public void setLocation(String location) {
        this.location = location;
    }

    @Override
    public String toString() {
        return "Address{" +
                "location='" + location + '\'' +
                '}';
    }
}

City.java

package jsondemo;

public class City {
    private String name;
    private String province;

    public City() {
    }

    public City(String name, String province) {
        this.name = name;
        this.province = province;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getProvince() {
        return province;
    }

    public void setProvince(String province) {
        this.province = province;
    }

    @Override
    public String toString() {
        return "City{" +
                "name='" + name + '\'' +
                ", province='" + province + '\'' +
                '}';
    }
}

Output

{
  "id": 1,
  "name": "Andrew Programming",
  "number": [
    1234123,
    4123123
  ],
  "address": {
    "location": "california"
  },
  "cityList": [
    {
      "name": "LA",
      "province": "CA"
    },
    {
      "name": "NY",
      "province": "NY"
    }
  ],
  "contractor": false,
  "role": "Manager"
}

Convert json to java object

package jsondemo;

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

import java.io.File;
import java.io.IOException;

public class JSONToJavaExample {
    public static void main(String[] args) {
        Employee employee = null;
        ObjectMapper mapper = new ObjectMapper();
        try {
            employee = mapper.readValue(new File("employee.json"), Employee.class);
            System.out.println(employee);
        } catch (JsonGenerationException e) {

        } catch (JsonParseException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Source Code

https://github.com/AndrewProgramming/LearnJavaByExample