In this post, we will see about an exception: No qualifying Bean of type. Exceptions are least expected but you might get it while working with Spring. or Spring boot.

Did you get this exception: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type?

If yes, let’s see different reasons for it.

Reason 1:
You forgot to declare the bean itself.

Let’s understand this with the help of example.

XML configuration

1. Create a simple java maven project.
2. Maven dependency
put spring and cglib maven dependency in pom.xml.

org.springframework
   spring-core
   ${spring.version}org.springframework
   spring-webmvc
   ${spring.version}cglib
            cglib
            3.04.2.1.RELEASE

So your pom.xml will look like:

org.arpit.java2blog
  SpringHelloWorldJavaBasedConfiguration
  0.0.1-SNAPSHOTSpringHelloWorldJavaBasedConfigurationIt provides hello world program for java based config
org.springframework
   spring-core
   ${spring.version}org.springframework
   spring-webmvc
   ${spring.version}cglib
            cglib
            3.04.2.1.RELEASE

3. Create Bean class

package org.arpit.java2blog;

import org.springframework.beans.factory.annotation.Autowired;

public class X {

	@Autowired
	Y y;

	public Y getY() {
		return y;
	}

	public void setY(Y y) {
		this.y = y;
	}
}

Please note that we are using Autowired annotation to inject bean y in x.

package org.arpit.java2blog;

public class Y {

	public void methodY()
	{
		System.out.println("In method Y");
	}
	
}

4. ApplicationContext.xml
Create ApplicationContext.xml in src/main/resources as below.

We have just declared one bean x here
5. Create SpringApplicationMain.java

package org.arpit.java2blog;

import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * 
 *  Spring Application main
 */
public class SpringApplicationMain 
{
	public static void main( String[] args )
	{
		ClassPathXmlApplicationContext ac = new ClassPathXmlApplicationContext("ApplicationContext.xml");
		X firstX = (X) ac.getBean("x");
		Y firstY = firstX.getY();
		ac.close();	
	}
}

6. Run it
When you run above program, you will get below output.

As you can see, we are getting NoSuchBeanDefinitionException: No qualifying bean of type as there is no bean “y” declared in XML.

Java configuration

First 2 steps will remain the same.
let’s add @Component to X.java

package org.arpit.java2blog;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class X {

	@Autowired
	Y y;

	public Y getY() {
		return y;
	}

	public void setY(Y y) {
		this.y = y;
	}
}

package org.arpit.java2blog;

public class Y {

	public void methodY()
	{
		System.out.println("In method Y");
	}
	
}

4. Create ApplicationConfiguration.java as below.

package org.arpit.java2blog;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan("org.arpit.java2blog")
public class ApplicationConfiguration {


}

5. Create Main class

package org.arpit.java2blog;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;;

public class SpringJavaConfigMain {

	public static void main(String[] args) {
		@SuppressWarnings("resource")
		ApplicationContext appContext = new AnnotationConfigApplicationContext(ApplicationConfiguration.class);
		X x = (X) appContext.getBean("x");
		Y y = x.getY();
	}
}

6. Run it
When you run it, you will get below output.

If you add @Component to Y.java, above exception won’t occur.

Reason 2:
You have not added package name to @ComponentScan.

You might be using @Component,@Service or @Repository but there is no entry for package with @ComponentScan.
For example:
If I change package name to “org.arpit.dummy”, program won’t work,even if you have put @Component with bean Y.

package org.arpit.java2blog;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan("org.arpit.dummy")
public class ApplicationConfiguration {


}

Reason 3:
You have more than one candidate for autowiring

Let’s understand this with the help of example.
Let’s say you one interface named “Decorable”

package org.arpit.java2blog;

public interface Decorable {
	public void decorate();
}

This interface is implemented by two classes.
CurtianDecorator.java

package org.arpit.java2blog;

import org.springframework.stereotype.Component;

@Component
public class CurtianDecorator implements Decorable {

	@Override
	public void decorate() {
		System.out.println("Decorating room using curtains");
		
	}
}

WallDecorator.java

package org.arpit.java2blog;

import org.springframework.stereotype.Component;

@Component
public class WallDecorator implements Decorable {

	@Override
	public void decorate() {
		System.out.println("Decorating room with wall decorators");

	}

}

Create Room.java which will composite reference variable of type interface Decorable.

package org.arpit.java2blog;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class Room {
	
	@Autowired
	Decorable decorable;

	public Decorable getDecorable() {
		return decorable;
	}

	public void setDecorable(Decorable decorable) {
		this.decorable = decorable;
	}
}

4. Create ApplicationConfiguration.java as below.

package org.arpit.java2blog;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan("org.arpit.java2blog")
public class ApplicationConfiguration {


}

5. Create Main class

package org.arpit.java2blog;
package org.arpit.java2blog;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;;

public class SpringJavaConfigMain {

	public static void main(String[] args) {
		@SuppressWarnings("resource")
		ApplicationContext appContext = new AnnotationConfigApplicationContext(ApplicationConfiguration.class);
		Room room=(Room)appContext.getBean("room");
		Decorable decorable = room.getDecorable();
		decorable.decorate();
	}
}

6. Run it
When you run it, you will get below output.

Please note that this time,we are getting NoUniqueBeanDefinitionException because there are two autowired candidates for Decorable in Room class and spring is not able to resolve which one to use.
You can solve this probem using @Qualifier annotation.

package org.arpit.java2blog;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;

@Component
public class Room {
	
	@Autowired
	@Qualifier("wallDecorator")
	Decorable decorable;

	public Decorable getDecorable() {
		return decorable;
	}

	public void setDecorable(Decorable decorable) {
		this.decorable = decorable;
	}
}

When you run the program again, you will get below output:

That’s all about no qual

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