Spring Boot application.properties value not populating

The user "geoand" is right in pointing out the reasons here and giving a solution. But a better approach is to encapsulate your configuration into a separate class, say SystemContiguration java class and then inject this class into what ever services you want to use those fields.

Your current way(@grahamrb) of reading config values directly into services is error prone and would cause refactoring headaches if config setting name is changed.

The way you are performing the injection of the property will not work, because the injection is done after the constructor is called.

You need to do one of the following:

Better solution

@Component
public class MyBean {

    private final String prop;

    @Autowired
    public MyBean(@Value("${some.prop}") String prop) {
        this.prop = prop;
        System.out.println("================== " + prop + "================== ");
    }
}

Solution that will work but is less testable and slightly less readable

@Component
public class MyBean {

    @Value("${some.prop}")
    private String prop;

    public MyBean() {

    }

    @PostConstruct
    public void init() {
        System.out.println("================== " + prop + "================== ");
    }
}

Also note that is not Spring Boot specific but applies to any Spring application