Java – BeanCurrentlyInCreationException when @Autowired and @Bean are present in same class

autowiredcircular-dependencyjavajavabeansspring

@Configuration
public class Test1 {

    @Autowired
    private Test3 test3;

}

@Configuration
public class Test2 {

    @Autowired
    private Test3 test3;

    @Bean(name = "test3 ")
    Test3 test3 () {
        return new Test3(); 
    }
}

The above code gives the following error.

Caused by:
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'test1': Injection of autowired dependencies failed;
nested exception is
org.springframework.beans.factory.BeanCreationException: Could not autowire field: private Test3 com.package.name.Test1.test3;

nested exception is
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'test2': Injection of autowired dependencies failed;
nested exception is
org.springframework.beans.factory.BeanCreationException: Could not autowire field: private Test3 com.package.name.Test2.test3;

nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'test3': Requested bean is currently in creation: Is there an unresolvable circular reference?

How is this an example of circular dependency? If it is, any ideas on resolving this.

Best Answer

You don't need to autowire a bean defined in the same class since you can just reference that bean directly by calling the initialising method test3().

@Configuration
public class Test2{

    @Bean(name = "test3 ")
    Test3 test3 () {
        return new Test3(); 
    }

    public void exampleOfUsingTest3Bean() {
        System.out.println("My test3 bean is" + test3().toString());
    }
}

And, indeed, you should not do what you were trying to do since @Autowired fields are injected into a class on construction of the class and at this point no bean called Test3 exists because it is defined by a method of the class being constructed. Theoretically you could define this @Bean method to be static and it should be available to autowire but you shouldn't do this.

@Bean(name = "test3 ")
public static Test3 test3 () {
    return new Test3(); 
}

Related Solutions

Java – What are the differences between a HashMap and a Hashtable in Java

There are several differences between HashMap and Hashtable in Java:

Hashtable is synchronized, whereas HashMap is not. This makes HashMap better for non-threaded applications, as unsynchronized Objects typically perform better than synchronized ones.
Hashtable does not allow null keys or values. HashMap allows one null key and any number of null values.
One of HashMap's subclasses is LinkedHashMap, so in the event that you'd want predictable iteration order (which is insertion order by default), you could easily swap out the HashMap for a LinkedHashMap. This wouldn't be as easy if you were using Hashtable.

Since synchronization is not an issue for you, I'd recommend HashMap. If synchronization becomes an issue, you may also look at ConcurrentHashMap.

Java inner class and static nested class

From the Java Tutorial:

Nested classes are divided into two categories: static and non-static. Nested classes that are declared static are simply called static nested classes. Non-static nested classes are called inner classes.

Static nested classes are accessed using the enclosing class name:

OuterClass.StaticNestedClass

For example, to create an object for the static nested class, use this syntax:

OuterClass.StaticNestedClass nestedObject = new OuterClass.StaticNestedClass();

Objects that are instances of an inner class exist within an instance of the outer class. Consider the following classes:

class OuterClass {
    ...
    class InnerClass {
        ...
    }
}

An instance of InnerClass can exist only within an instance of OuterClass and has direct access to the methods and fields of its enclosing instance.

To instantiate an inner class, you must first instantiate the outer class. Then, create the inner object within the outer object with this syntax:

OuterClass outerObject = new OuterClass()
OuterClass.InnerClass innerObject = outerObject.new InnerClass();

see: Java Tutorial - Nested Classes

For completeness note that there is also such a thing as an inner class without an enclosing instance:

class A {
  int t() { return 1; }
  static A a =  new A() { int t() { return 2; } };
}

Here, new A() { ... } is an inner class defined in a static context and does not have an enclosing instance.

Best Answer

Related Solutions

Java – What are the differences between a HashMap and a Hashtable in Java

Java inner class and static nested class

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