@Autowired Environment is always null

Question

I am having a simple RestController:

@RestController
@PropertySource("classpath:application.properties")
public class Word2VecRestController {

    private final static Logger LOGGER = Logger.getLogger(Word2VecRestController.class);

    // @Resource is not working as well
    @Autowired
    Environment env;

    // This is working for some reason 
    // but it's null inside the constructor
    @Value("${test}") 
    String test;

    public Word2VecRestController() {

        LOGGER.info(env.getProperty("test"));

        System.out.println("");

    }

    @GetMapping("/dl4j/getWordVector")
    public ResponseEntity<List<Double[]>> getWordVector(String word) {
        return null;
    }

}

The problem is, that env is always null. I've seen somewhere that I could try to use @Resource instead of @Autowired but that didn't help.

application.properties:

test=helloworld

I've tried to use

@Value("${test}")
String test;

but the problem here is that these are null during construction of the object where I need it.

Answer 1

Field injection is done by Spring after the constructor is called. This is why Environment is null in the Word2VecRestController constructor. You can try constructor injection if you need it in the constructor:

@RestController
@PropertySource("classpath:application.properties")
public class Word2VecRestController {

    private final static Logger LOGGER = Logger.getLogger(Word2VecRestController.class);

    @Autowired
    public Word2VecRestController(Environment env, @Value("${test}") String test) {

        LOGGER.info(env.getProperty("test"));

        System.out.println("");

    }

    @GetMapping("/dl4j/getWordVector")
    public ResponseEntity<List<Double[]>> getWordVector(String word) {
        return null;
    }

}

PS: if you use Spring Boot, you do not need the @PropertySource("classpath:application.properties"), this is automatically done for you.