BeanCurrentlyInCreationException: Error creating bean with name : Requested bean is currently in creation: Is there an unresolvable circular reference?

In this post we will see how to resolve this exception-"BeanCurrentlyInCreationException: Error creating bean with name : Requested bean is currently in creation: Is there an unresolvable circular reference?" in spring.This exception is thrown in the below scenario:

1. When there is an circular reference between the beans. For instance ClassA contains the instance member of type ClassB and class B too has ClassA as instance member. 
2. And we use the constructor arguments to inject the dependencies between these beans.

Below code sample will explain this scenario.

• ClassA,ClassB- bean classes for which there is an  circular dependencies between them.
• CircularDemo -Main class which will load and initialize the spring container.
• circontext.xml - metadata configuration details for the spring container.

ClassA.java

package test; public class ClassA { private ClassB classB=null; public ClassB getClassB() { return classB; } public void setClassB(ClassB classB) { this.classB = classB; } @Override public String toString() { return "ClassA"; } }

ClassB.java

package test; public class ClassB { private ClassA classA=null; public ClassA getClassA() { return classA; } public void setClassA(ClassA classA) { this.classA = classA; } @Override public String toString() { return "ClassB"; } }

circontext.xml

<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd"> <bean id="classA" class="test.ClassA"> <constructor-arg ref="classB"/> </bean> <bean id="classB" class="test.ClassB"> <constructor-arg ref="classA"/> </bean> </beans>

As we can see in the application context file,we used the constructor arguments to inject the dependencies for bean ClassA and ClassB

CircularDemo.java

package test; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class CircularDemo { public static void main(String[] args) { // TODO Auto-generated method stub ApplicationContext bf= new ClassPathXmlApplicationContext(new String[]                {"circontext.xml"}); ClassA classA= bf.getBean("classA",ClassA.class);    System.out.println("Bean Loaded:"+classA); } }

OUTPUT:

When we run the main program - CircularDemo,we will get the below exception

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'classA' defined in class path resource [circontext.xml]: Cannot resolve reference to bean 'classB' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'classB' defined in class path resource [circontext.xml]: Cannot resolve reference to bean 'classA' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'classA': Requested bean is currently in creation: Is there an unresolvable circular reference?

To resolve this exception,declare the dependencies between the beans through the property setters instead of the constructor arguments as shown below.

<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd"> <bean id="classA" class="test.ClassA"> <property name="classB" ref="classB"/> </bean> <bean id="classB" class="test.ClassB"> <property name="classA" ref="classA"/> </bean> </beans>

Now if we run the CircularDemo with the above application context file,we will get the expected output.

Bean Loaded:ClassA