How to resolve cyclic dependencies when using Dependency Injection?

Cyclic dependencies in Dependency Injection occur when two or more components depend on each other directly, leading to a loop during instance creation.

To resolve this issue in Java, several approaches can be used:

1. Refactoring architecture — reconsider the design to eliminate dependency cycles, for example, by extracting common dependencies into a separate component.

2. Using lazy initialization (Lazy Injection) — inject dependencies via Provider<T> or ObjectFactory<T> to create objects only when needed, not immediately.

3. Setter injection — instead of constructor injection, use setters, which allows creating objects without fully initializing dependencies, and then setting them.

4. Using @Lazy in Spring — the annotation causes Spring to create proxies and initialize beans on demand, breaking the cycle.

Example using @Lazy in Spring:

@Component
public class A {
    private final B b;

    public A(@Lazy B b) {
        this.b = b;
    }
}

@Component
public class B {
    private final A a;

    public B(A a) {
        this.a = a;
    }
}

Here, @Lazy on the constructor parameter of class A allows Spring to create a proxy for B and avoid cyclic dependency during initialization.