[FIXED] What are the differences between @PostConstruct and Autowired Constructor?

Issue

I'd like to know what are the differences between the two examples below. One is using @PostConstruct init method to ensure autowired bean is initialized, and the other one is using constructor with @Autowired to ensure any needed beans are initialized.

I am curious

1. If there is any functional differences
2. If one is better than the other, why? (Maybe initialization speed, less call stack, less memory usage, etc.)

Thanks in advance :)

@Component
public class MyBean {

    @Autowired
    public MyBean(SomeOtherBean someOtherBean) {
        ...
    }
    ...
}

@Component
public class MyBean {

    @Autowired 
    private SomeOtherBean someOtherBean;

    @PostConstruct
    public void init() {
        ...
    }
    ...
}

Solution

in the first case, if I'm going to use MyBean.class without in a none Spring framework project I'll need to pass SomeOtherBean so I know the object is created correctly. but in the second case, I would have done new MyBean() and then after I'll get NullPointerException when using it because the object depends on SomeOtherBean. so the first one is much cleaner.

Answered By - stacker
Answer Checked By - Cary Denson (JavaFixing Admin)