This post explains marshalling a java object to YAML format and storing it to a file. This can be achieved with the help of YAMLMapper provided by jackson package.
To explain with an example we will use the below pojo objects.

Employee

package package2;

import java.math.BigDecimal;
import java.util.List;

public class Employee {
    private String id;
    private String name;
    private String status;
    private BigDecimal salary;
    private List phoneNumbers;
    
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getStatus() {
        return status;
    }
    public void setStatus(String status) {
        this.status = status;
    }
    public BigDecimal getSalary() {
        return salary;
    }
    public void setSalary(BigDecimal salary) {
        this.salary = salary;
    }
    public List getPhoneNumbers() {
        return phoneNumbers;
    }
    public void setPhoneNumbers(List phoneNumbers) {
        this.phoneNumbers = phoneNumbers;
    }
    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append(this.id).append(",");
        sb.append(this.name).append(",");
        sb.append(this.status).append(",");
        sb.append(this.salary);
        return sb.toString();
    }
}

Now the main code which does the marshalling from java object to YAML format.

Main Code

1  package package2;
2  
3  import java.io.File;
4  import java.io.IOException;
5  import java.math.BigDecimal;
6  import java.util.ArrayList;
7  import java.util.List;
8  
9  import com.fasterxml.jackson.core.JsonGenerationException;
10 import com.fasterxml.jackson.databind.JsonMappingException;
11 import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;
12 
13 public class YAMLDemo1 {
14  public static void main(String[] args) throws JsonGenerationException, JsonMappingException, IOException {
15      List phoneNumbers = new ArrayList();
16      phoneNumbers.add("phoneNumber1");
17      phoneNumbers.add("phoneNumber2");
18      
19      Employee employee = new Employee();
20      employee.setId("1");
21      employee.setName("name1");
22      employee.setSalary(new BigDecimal(1000));
23      employee.setStatus("NEW");
24      employee.setPhoneNumbers(phoneNumbers);
25 
26      File file = new File("Output2.yml");
27      
28      YAMLMapper yamlMapper = new YAMLMapper();
29      yamlMapper.writeValue(file, employee);
30  }
31 }

As shown in the main code, we create an instance of YAMLMapper. Refer to line 28

YAMLMapper yamlMapper = new YAMLMapper();

Then we instruct the yamlMapper to convert the java object to YAML formant and save to a file as shown below. Refer to line 29

yamlMapper.writeValue(file, user);

Output

---

id: “1”
name: “name1”
status: “NEW”
salary: 1000
phoneNumbers:
– “phoneNumber1”
– “phoneNumber2”