Spring @Autowired Annotation

Published on August 3, 2022


Spring @Autowired Annotation

While we believe that this content benefits our community, we have not yet thoroughly reviewed it. If you have any suggestions for improvements, please let us know by clicking the “report an issue“ button at the bottom of the tutorial.

Spring @Autowired annotation is used for automatic dependency injection. Spring framework is built on dependency injection and we inject the class dependencies through spring bean configuration file.

Spring @Autowired Annotation

spring @autowired annotation, @Autowired, spring autowiring, spring @autowired Usually we provide bean configuration details in the spring bean configuration file and we also specify the beans that will be injected in other beans using ref attribute. But Spring framework provides autowiring features too where we don’t need to provide bean injection details explicitly. There are different ways through which we can autowire a spring bean.

  1. autowire byName - For this type of autowiring, setter method is used for dependency injection. Also the variable name should be same in the class where we will inject the dependency and in the spring bean configuration file.
  2. autowire byType - For this type of autowiring, class type is used. So there should be only one bean configured for this type in the spring bean configuration file.
  3. autowire by constructor - This is almost similar to autowire byType, the only difference is that constructor is used to inject the dependency.
  4. autowire by autodetect - If you are on Spring 3.0 or older versions, this is one of the autowire options available. This option was used for autowire by constructor or byType, as determined by Spring container. Since we already have so many options, this option is deprecated. I will not cover this option in this tutorial.
  5. @Autowired annotation - We can use Spring @Autowired annotation for spring bean autowiring. @Autowired annotation can be applied on variables and methods for autowiring byType. We can also use @Autowired annotation on constructor for constructor based spring autowiring. For @Autowired annotation to work, we also need to enable annotation based configuration in spring bean configuration file. This can be done by context:annotation-config element or by defining a bean of type org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.
  6. @Qualifier annotation - This annotation is used to avoid conflicts in bean mapping and we need to provide the bean name that will be used for autowiring. This way we can avoid issues where multiple beans are defined for same type. This annotation usually works with the @Autowired annotation. For constructors with multiple arguments, we can use this annotation with the argument names in the method.

By default spring bean autowiring is turned off. Spring bean autowire default value is “default” that means no autowiring is to be performed. autowire value “no” also have the same behavior. To showcase the use of Spring Bean autowiring, let’s create a simple Spring Maven project. Our final project will look like below image. Spring @Autowired, Spring autowiring, @Autowired annotation Let’s look into each of the autowire options one by one. For that we will create a Model bean and a service class where we will inject the model bean.

Spring @Autowired Annotation - Maven Dependencies

For spring autowiring, we don’t need to add any additional dependencies. Our pom.xml file has spring framework core dependencies and looks like below.

<project xmlns="https://maven.apache.org/POM/4.0.0" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="https://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">


		<!-- Generic properties -->

		<!-- Spring -->

		<!-- Logging -->


		<!-- Spring and Transactions -->

		<!-- Logging with SLF4J & LogBack -->


Spring @Autowired Annotation - Model Bean

Let’s create a simple Java Bean, named Employee. This bean will have a single property with getter and setter methods. We will initialize this property value in the spring bean configuration file.

package com.journaldev.spring.autowiring.model;

public class Employee {

	private String name;

	public String getName() {
		return name;

	public void setName(String name) {
		this.name = name;

Spring @Autowired Annotation - Service Class

Let’s create our service class in which we will inject Employee bean through spring autowiring.

package com.journaldev.spring.autowiring.service;

import com.journaldev.spring.autowiring.model.Employee;

public class EmployeeService {

	private Employee employee;

	// constructor is used for autowire by constructor
	public EmployeeService(Employee emp) {
		System.out.println("Autowiring by constructor used");
		this.employee = emp;

	// default constructor to avoid BeanInstantiationException for autowire
	// byName or byType
	public EmployeeService() {
		System.out.println("Default Constructor used");

	// used for autowire byName and byType
	public void setEmployee(Employee emp) {
		this.employee = emp;

	public Employee getEmployee() {
		return this.employee;

We will use the same service class for perform spring autowiring byName, byType and by constructor. The setter method will be used for spring autowiring byName and byType whereas constructor based injection will be used by constructor autowire attribute. When we use spring autowire byName or byType, default constructor is used. That’s why we have explicitly defined the default constructor for the EmployeeService bean.

Spring @Autowired Annotation - autowiring byType Example

Let’s create a separate class with Spring @Autowired annotation for autowiring byType.

package com.journaldev.spring.autowiring.service;

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

import com.journaldev.spring.autowiring.model.Employee;

public class EmployeeAutowiredByTypeService {

	//Autowired annotation on variable/setters is equivalent to autowire="byType"
	private Employee employee;
	public void setEmployee(Employee emp){
	public Employee getEmployee(){
		return this.employee;

Note that I have annotated both Employee variable and it’s setter method with Spring @Autowired annotation, however only one of these is sufficient for spring bean autowiring.

Spring @Autowired Annotation and @Qualifier Bean autowiring by constructor Example

Let’s create another service class where we will use @Autowired annotation for constructor based injection. We will also see @Qualifier annotation usage.

package com.journaldev.spring.autowiring.service;

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

import com.journaldev.spring.autowiring.model.Employee;

public class EmployeeAutowiredByConstructorService {

	private Employee employee;

	//Autowired annotation on Constructor is equivalent to autowire="constructor"
	public EmployeeAutowiredByConstructorService(@Qualifier("employee") Employee emp){
	public Employee getEmployee() {
		return this.employee;

When this bean will be initialized by Spring framework, bean with name as “employee” will be used for autowiring. Spring @Autowired annotation excepts one argument “required” that is a boolean with default value as TRUE. We can define it to be “false” so that spring framework don’t throw any exception if no suitable bean is found for autowiring.

Spring @Autowired Annotation - Bean Configuration File

Spring bean configuration file is the main part of any spring application, let’s see how our spring bean configuration file looks and then we will look into each part of it.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="https://www.springframework.org/schema/beans"
	xsi:schemaLocation="https://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd
		https://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context-4.0.xsd"
		default-autowire="byName" default-autowire-candidates="*" >

<bean name="employee" class="com.journaldev.spring.autowiring.model.Employee">
	<property name="name" value="Pankaj"></property>

<bean name="employee1" class="com.journaldev.spring.autowiring.model.Employee" autowire-candidate="false">
	<property name="name" value="Dummy Name"></property>

<!-- autowiring byName, bean name should be same as the property name -->
<bean name="employeeServiceByName" class="com.journaldev.spring.autowiring.service.EmployeeService" autowire="byName" />

<!-- autowiring byType, there should be only one bean definition for the mapping -->
<bean name="employeeServiceByType" class="com.journaldev.spring.autowiring.service.EmployeeService" autowire="byType" />

<!-- autowiring by constructor -->
<bean name="employeeServiceConstructor" class="com.journaldev.spring.autowiring.service.EmployeeService" autowire="constructor" />

<!-- Enable Annotation based configuration -->
<context:annotation-config />

<!-- using @Autowiring annotation in below beans, byType and constructor -->
<bean name="employeeAutowiredByTypeService" class="com.journaldev.spring.autowiring.service.EmployeeAutowiredByTypeService" />
<bean name="employeeAutowiredByConstructorService" class="com.journaldev.spring.autowiring.service.EmployeeAutowiredByConstructorService" />

Important points about spring bean configuration file are:

  • beans element default-autowire is used to define the default autowiring method. Here I am defining the default autowiring method to be byName.
  • beans element default-autowire-candidates is used to provide the pattern for bean names that can be used for autowiring. For simplicity I am allowing all the bean definitions to be eligible for autowiring, however if we can define some pattern for autowiring. For example, if we want only DAO bean definitions for autowiring, we can specify it as default-autowire-candidates="*DAO".
  • autowire-candidate="false" is used in a bean definition to make it ineligible for autowiring. It’s useful when we have multiple bean definitions for a single type and we want some of them not to be autowired. For example, in above spring bean configurations “employee1” bean will not be used for autowiring.
  • autowire attribute byName, byType and constructor is self understood, nothing much to explain there.
  • context:annotation-config is used to enable annotation based configuration support. Notice that employeeAutowiredByTypeService and employeeAutowiredByConstructorService beans don’t have autowire attributes.

Spring @Autowired Annotation - Test Program

Now that our spring application is ready with all types of spring autowiring, let’s write a simple test program to see if it works as expected or not.

package com.journaldev.spring.autowiring.main;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.journaldev.spring.autowiring.service.EmployeeAutowiredByConstructorService;
import com.journaldev.spring.autowiring.service.EmployeeAutowiredByTypeService;
import com.journaldev.spring.autowiring.service.EmployeeService;

public class SpringMain {

	public static void main(String[] args) {
		ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("spring.xml");
		EmployeeService serviceByName = ctx.getBean("employeeServiceByName", EmployeeService.class);
		System.out.println("Autowiring byName. Employee Name="+serviceByName.getEmployee().getName());
		EmployeeService serviceByType = ctx.getBean("employeeServiceByType", EmployeeService.class);
		System.out.println("Autowiring byType. Employee Name="+serviceByType.getEmployee().getName());
		EmployeeService serviceByConstructor = ctx.getBean("employeeServiceConstructor", EmployeeService.class);
		System.out.println("Autowiring by Constructor. Employee Name="+serviceByConstructor.getEmployee().getName());
		//printing hashcode to confirm all the objects are of different type
		//Testing @Autowired annotations
		EmployeeAutowiredByTypeService autowiredByTypeService = ctx.getBean("employeeAutowiredByTypeService",EmployeeAutowiredByTypeService.class);
		System.out.println("@Autowired byType. Employee Name="+autowiredByTypeService.getEmployee().getName());

		EmployeeAutowiredByConstructorService autowiredByConstructorService = ctx.getBean("employeeAutowiredByConstructorService",EmployeeAutowiredByConstructorService.class);
		System.out.println("@Autowired by Constructor. Employee Name="+autowiredByConstructorService.getEmployee().getName());


The program is simple, we are just creating the spring application context and using it to get different beans and printing the employee name. When we run above application, we get following output.

Mar 31, 2014 10:41:58 PM org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@3fa99295: startup date [Mon Mar 31 22:41:58 PDT 2014]; root of context hierarchy
Mar 31, 2014 10:41:58 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [spring.xml]
Default Constructor used
Default Constructor used
Autowiring by constructor used
Autowiring byName. Employee Name=Pankaj
Autowiring byType. Employee Name=Pankaj
Autowiring by Constructor. Employee Name=Pankaj
@Autowired byType. Employee Name=Pankaj
@Autowired by Constructor. Employee Name=Pankaj
Mar 31, 2014 10:41:58 PM org.springframework.context.support.ClassPathXmlApplicationContext doClose
INFO: Closing org.springframework.context.support.ClassPathXmlApplicationContext@3fa99295: startup date [Mon Mar 31 22:41:58 PDT 2014]; root of context hierarchy

As you can see that for autowire byName and byType, default no-args constructor is used to initialize the bean. For autowire by constructor, parameter based constructor is used. From the hashcode of all the variables, we have confirmed that all the spring beans are different objects and not referring to the same object. Since we removed “employee1” from the list of eligible beans for autowiring, there was no confusion in the bean mapping. If we remove autowire-candidate="false" from the “employee1” definition, we will get below error message when executing the above main method.

Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'employeeServiceByType' defined in class path resource [spring.xml]: Unsatisfied dependency expressed through bean property 'employee': : No qualifying bean of type [com.journaldev.spring.autowiring.model.Employee] is defined: expected single matching bean but found 2: employee,employee1; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.journaldev.spring.autowiring.model.Employee] is defined: expected single matching bean but found 2: employee,employee1
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireByType(AbstractAutowireCapableBeanFactory.java:1278)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1170)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:700)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
	at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
	at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
	at com.journaldev.spring.autowiring.main.SpringMain.main(SpringMain.java:12)
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.journaldev.spring.autowiring.model.Employee] is defined: expected single matching bean but found 2: employee,employee1
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:967)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:855)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireByType(AbstractAutowireCapableBeanFactory.java:1263)
	... 13 more

That’s all for the Spring @Autowired Annotation and Spring autowiring feature, please download the example project from below link and analyse it to learn more.

Download Spring Bean Autowiring Project

Thanks for learning with the DigitalOcean Community. Check out our offerings for compute, storage, networking, and managed databases.

Learn more about us

About the authors
Default avatar


Still looking for an answer?

Ask a questionSearch for more help

Was this helpful?
DigitalOcean Employee
DigitalOcean Employee badge
February 19, 2020

Hi Pankaj, Thank you for the tutorial. I have little confusion i.e if I have 2 beans in .xml file with names “employee” and “employee1” and as per employeeAutowiredByTypeService bean, It would create a bean of EmployeeAutowiredByTypeService.class till this part I am clear. Once you are getting this employeeAutowiredByTypeService obj and calling for “autowiredByTypeService.getEmployee().getName()”, then in such case which object would come because both “employee” and “employee1” are of type “Employee” how to solve this kind of collision, should we use @Qualifier(“nameOfBean”) annotation or by default does it pick up anyone? Please help me with this query.

- Raghu Ram

    DigitalOcean Employee
    DigitalOcean Employee badge
    September 27, 2019

    Description Resource Location Path Type ClassPathXmlApplicationContext cannot be resolved to a type SpringMain.java line 13 /SpringBeanAutowiring/src/main/java/com/journaldev/spring/autowiring/main Java Problem I am not able to find issue . please check

    - pankaj

      DigitalOcean Employee
      DigitalOcean Employee badge
      March 8, 2019

      I hope I can get answer. I’m trying to create multiple object in bean configuration but it throws me an error It throws an exception of a conflict. But it doesn’t give any error when I instantiate random named service objects autowiredByConstructorService = ctx.getBean(“employeeAutowiredByConstructorService”,EmployeeAutowiredByConstructorService.class); w

      - andy

        DigitalOcean Employee
        DigitalOcean Employee badge
        May 18, 2018

        Hi when your page reload it ask for allow for show notification. I want to implement the same on my website. My website is built on spring and jsp. Please help me to do. Thankyou

        - Abhishek

          DigitalOcean Employee
          DigitalOcean Employee badge
          May 17, 2018

          Above statement is wrong. It actually call the setter method. So if bean name is employee, it will call setEmployee method. Even if you change the property name to emp, it will work. Usually we make sure property name and bean name is same. Then just follow the naming convention of setter method. So it works and give impression that property name and bean name should be same.

          - Rohit

            DigitalOcean Employee
            DigitalOcean Employee badge
            July 15, 2017

            If you write the configure your beans via javaConfig.java, instead of using .xml file that would be better.

            - SprinfDev

              DigitalOcean Employee
              DigitalOcean Employee badge
              December 2, 2015

              Its nice explanation.

              - ramesh

                DigitalOcean Employee
                DigitalOcean Employee badge
                September 17, 2015

                clean explanation sir

                - bala

                  DigitalOcean Employee
                  DigitalOcean Employee badge
                  May 31, 2015

                  Thanks, nice post

                  - Binh Nguyen

                    DigitalOcean Employee
                    DigitalOcean Employee badge
                    April 22, 2015

                    how can i integrate webserices with spring framework

                    - Lalu

                      Try DigitalOcean for free

                      Click below to sign up and get $200 of credit to try our products over 60 days!

                      Sign up

                      Join the Tech Talk
                      Success! Thank you! Please check your email for further details.

                      Please complete your information!

                      Featured on Community

                      Get our biweekly newsletter

                      Sign up for Infrastructure as a Newsletter.

                      Hollie's Hub for Good

                      Working on improving health and education, reducing inequality, and spurring economic growth? We'd like to help.

                      Become a contributor

                      Get paid to write technical tutorials and select a tech-focused charity to receive a matching donation.

                      Welcome to the developer cloud

                      DigitalOcean makes it simple to launch in the cloud and scale up as you grow — whether you're running one virtual machine or ten thousand.

                      Learn more
                      DigitalOcean Cloud Control Panel