Spring Framework FAQ: Top Questions

Spring can resolve circular dependencies between beans using setter injection. Constructor-based circular dependencies are not resolved automatically.

📘 Explanation:

• Setter injection: Spring creates proxies and injects dependencies post-instantiation.
• Constructor injection: Causes BeanCurrentlyInCreationException.

📥 Example:

public class A {
  private B b;
  public void setB(B b) { this.b = b; }
}

public class B {
  private A a;
  public void setA(A a) { this.a = a; }
}

🏆 Expected Output:

Spring injects A and B into each other using setter methods.

🛠️ Use Cases:

• Legacy code migration where cycles exist.
• Bidirectional relationships in domain models.