Circular dependency in spring

Summary

• Circular dependency is a situation in Spring when two or more beans depend on each other.
• For example, when Bean A requires Bean B to perform its functions, and Bean B, in turn, requires Bean A for its operations.
• Now if we try to use constructor injection for the above Circular dependent beans, then Spring will throw an exception called BeanCurrentlyInCreationException.

`

<bean class="in.scalive.beans.Teacher" id="t1">
    <constructor-arg ref="s1"/>
</bean>
<bean class="in.scalive.beans.Student" id="s1"> 
	<constructor-arg ref="t1"/>
</bean>

`

To solve this, spring gives us 3 approaches to solve circular dependency

• Setter Injection
• Using @Lazy annotation
• Using @PostConstruct annotation

Syntax

`

<bean class="com.circulardependency.demo.beans.Teacher" id="teacher">
    <property name="name" value="Mr.Kumar"/>
    <property name="useStudent" ref="useStudent"/>
</bean>

<bean class="com.circulardependency.demo.beans.Student" id="useStudent">
    <property name="name" value="Naveen"/>
    <property name="teacher" ref="teacher"/>
</bean>

`

• Note: Above XML configuration is using setter injection to resolve the circular dependency issue.