Cyclic dependency with constructor injection

Background

Spring is discouraging use of filed injection, and in favor or constructor injection.

However, when the beans need to cross reference to each other. For example:

class BeanA{
    @Autowired
    public BeanA(BeanB beanB) {
        this.beanB= beanB;
    }
}

class BeanB{
    @Autowired
    public BeanB(BeanA beanA) {
        this.beanA= beanA;
    }

this will instead throw out exception

APPLICATION FAILED TO START
***************************

Description:

The dependencies of some of the beans in the application context form a cycle:

┌─────┐
|  beanA defined in URL [jar:file:/...class]
↑     ↓
|  beanB defined in URL [jar:file:/....class]
↑     ↓
|  xx (field xx) 

Changes

Instead of just saying "Field injection is not recommended", can we make it clear, by adding

Field injection is not recommended **however, please don't constructor injection with circular reference** ?

?

Related Issues

• #25443
• #27534
• #30333

Start with the application-context startup failure and the circular-dependency diagnostic shown in this issue, then review related issues #25443, #27534, and #30333. Done means the diagnostic clearly warns about constructor injection with circular references without obscuring the existing cycle details.