Skip to main content

How to convert java object to Map or Properties

Sometimes, we may need to convert the java objet to key-value pairs, for example Map or Properties class. It can be doable in multiple ways like using reflection or jackson library. We are going to use jackson library to achieve it here.

Maven dependency


We will use this class to convert to map and properties class.
class Employee{
    private long id;
    private String name;
    private Integer age;

    public Employee(long id, String name, Integer age) {
        super(); = id; = name;
        this.age = age;

    //getter methods
    //setter methods

Generic method to convert the object

Jackson library provides ObjectMapper class which provides "convertValue" method to convert the java objects. Below is the code for our generic method which accepts the object to be converted and class to which it will convert the object.
public <T> T convertObjToMap(Object o, TypeReference<T> ref) {
    ObjectMapper mapper = new ObjectMapper();
    return mapper.convertValue(o, ref);

Execute the convert method

Below code will execute two scenarios, one to convert to Map and another to convert to Properties class.
    //Create java object to be converted
    Employee emp = new Employee(6L, "Emp-1", 30);

    //Convert to Map<String, String> class
    Map<String, String> map = convertObjToMap(emp, 
    new TypeReference<Map<String, String>>(){});
    System.out.println("Convert to Map<String, String> :");

    //Convert to Properties class
    Properties props = convertObjToMap(emp, new TypeReference<Properties>(){});
    System.out.println("\nConvert to Properties :");


Below is the output of above code execution
  Convert to Map :
  {id=6, name=Emp-1, age=30}

  Convert to Properties :
  {age=30, name=Emp-1, id=6}
Other links you may be interested in:
Annotation processor to generate DTO class from Entity class
Entity to DTO conversion using jackson


Popular Posts

Setting up kerberos in Mac OS X

Kerberos in MAC OS X Kerberos authentication allows the computers in same domain network to authenticate certain services with prompting the user for credentials. MAC OS X comes with Heimdal Kerberos which is an alternate implementation of the kerberos and uses LDAP as identity management database. Here we are going to learn how to setup a kerberos on MAC OS X which we will configure latter in our application. Installing Kerberos In MAC we can use Homebrew for installing any software package. Homebrew makes it very easy to install the kerberos by just executing a simple command as given below. brew install krb5 Once installation is complete, we need to set the below export commands in user's profile which will make the kerberos utility commands and compiler available to execute from anywhere. Open user's bash profile: vi ~/.bash_profile Add below lines: export PATH=/usr/local/opt/krb5/bin:$PATH export PATH=/usr/local/opt/krb5/sbin:$PATH export LDFLAGS=&

SpringBoot - @ConditionalOnProperty example for conditional bean initialization

@ConditionalOnProperty annotation is used to check if specified property available in the environment or it matches some specific value so it can control the execution of some part of code like bean creation. It may be useful in many cases for example enable/disable service if specific property is available. Below are the attributes which can be used for property check. havingValue - Provide the value which need to check against specified property otherwise it will check that value should not be false. matchIfMissing - If true it will match the condition and execute the annotated code when property itself is not available in environment. name - Name of the property to be tested. If you want to test single property then you can directly put the property name as string like "" and if you have multiple properties to test then you can put the names like {"prop.name1","prop.name2"} prefix - It can be use when you want to apply some prefix to

Multiple data source with Spring boot, batch and cloud task

Here we will see how we can configure different datasource for application and batch. By default, Spring batch stores the job details and execution details in database. If separate data source is not configured for spring batch then it will use the available data source in your application if configured and create batch related tables there. Which may be the unwanted burden on application database and we would like to configure separate database for spring batch. To overcome this situation we will configure the different datasource for spring batch using in-memory database, since we don't want to store batch job details permanently. Other thing is the configuration of  spring cloud task in case of multiple datasource and it must point to the same data source which is pointed by spring batch. In below sections, we will se how to configure application, batch and cloud task related data sources. Application Data Source Define the data source in application properties or yml con

Integrated/Kerberos authentication using Spring boot and SPNEGO API

In this tutorial we will learn how to use Spring boot and SPNEGO API to implement the kerberos or integrated authentication. Kerberos is developed by Massachusetts Institute of Technology (MIT) which is used to authenticate between trusted services using KDC tickets. For example email client, HR portal or employee portal in a corporate network where employee doesn't need to provide their user id & password to access these application in the same domain. Once they are logged in to their machine, they can access such services/application with kerberos authentication. I am using MAC OS X to demonstrate the kerberos authentication. I have used the same machine to configure and run the application backed with kerberos authentication and my KDC database & application reside on the same machine. Setting up kerberos  First of all we need to setup kerberos where we will configure the database, create user principals, create policies and keytabs. We need to create our applicatio