Should I annotate pojo class with @Component?

I searched whether I should annotate POJO with @Component or not. It seems like it is recommended not to annotate pojo.

Here is my OrderStatusMnemonic Configuration class that reads a txt file:

@Configuration
public class OrderStatusMnemonic {
	private static final Logger log = LoggerFactory.getLogger("OrderStatusMnemonic.class");
	
	private ResourceLoader resourceLoader;
	
	@Autowired
	public OrderStatus orderStatus;

	public OrderStatusMnemonic(ResourceLoader resourceLoader) {
		this.resourceLoader = resourceLoader;
	}
	
	@PostConstruct
	public void init() {
		try {
			log.info("Loading order-status-mnemonic file ");
		    Resource resource = resourceLoader.getResource("classpath:order-status-mnemonic.txt");
		    InputStream inputStream = resource.getInputStream();
		    
		    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));
		    
		    String str;
		    List<String> orderStatusMnemonicList = new ArrayList<>();
		    while ( (str = bufferedReader.readLine()) != null) {
		    	log.info("str = " + str);
		    		    	
		    	orderStatusMnemonicList.add(str);
		    }
		    
		    orderStatus.setValues(orderStatusMnemonicList);
		    
		    log.info("orderStatusMnemonicList = " + orderStatusMnemonicList.toString());
		    
		    
		} catch (IOException | NullPointerException e) {
			log.error("Failing to Load order status mnemonic file" + e.getMessage(), e);
		}
	}
		
}

OrderStatus POJO:

@Getter
@Setter
@ToString
public class OrderStatus {
	private List<String> values;
}

Since I am autowiring OrderStatus POJO class I am getting error:

> Consider defining a bean of type 'com.spectrum.sci.osm.orderstatus.OrderStatus' in your configuration.

@Component or @Autowired should be used only for classes managed by Spring. POJOs are not managed by Spring. So, should neither add @component nor you should autowire it. Since you are trying to autowire POJO class, you are getting error to define bean of type OrderStatus

Your OrderStatus as it is now does not need annotation @Component so you should not add it. Also you should not try to @Autowire it anywhere without @Component.

You surely can add @Component and then @Autowire it anywhere you need it but there is no point in it since you can more easy instantiate your POJO by just issuing new OrderStatus(). And it might also be a waste of resources.

Then, when do you need those two annotations? Whenever your POJO needs to become a managed bean. In other words when there is a need for Spring to do some automagical things. Consider your POJO would have something more complex, like (check the comments):

// Enables autowiring OrderStatus -> autowired OrderStatus is managed 
// by Spring
@Component 
public class OrderStatus {
    private List<String> values;
    // Then there is something to autowire to OrderStatus also
    // Without OrderStatus being managed by Spring this would be ignored!
    // But because managed, Spring autowires also this one
    // Of course SomeOtherManagedBean must be a @Component, for example
    @Autowired
    private SomeOtherManagedBean somb;
}

Any plain-vanilla Java Class which is being used as light weight bean and treated/called as POJO should not be bound with any of the Spring components.

The java class can be decorated with either of the spring annotations (i.e. @Component, @Service, @Bean, @Configuration) only if that class has been enhanced by adding extra flavour and only if that class is being used to support other classes with enhanced features other then getter setter properties.

@Autowired can be used only if the class is marked with any of the spring components as the @Autowired is spring annotation which would scan only those beans which are being managed withing Spring.