Spring - @Required Annotation

The @Required annotation was used before Spring 5.1 to bean property setter methods and it indicated that the affected bean property must be populated in XML configuration file at configuration time. Otherwise, the container throws a BeanInitializationException exception. Following is an example to show the use of @Required annotation.

The @Required annotation is deprecated and its alternative is to use constructor injection or using @Autowired annotation having required attribute as true by default.

Example - Usage of Constructor Injection

Let us take a look at a working Eclipse IDE in place and take the following steps to create a Spring application −

Student.java

package com.tutorialspoint;

public class Student {
   private Integer age;
   private String name;
   
   public Student(String name, Integer age) {
      this.name = name;
      this.age = age;
   }

   public Integer getAge() {
      return age;
   }
   
   public String getName() {
      return name;
   }
}

MainApp.java

package com.tutorialspoint;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainApp {
   public static void main(String[] args) {
      ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
      
      Student student = (Student) context.getBean("student");
      System.out.println("Name : " + student.getName() );
      System.out.println("Age : " + student.getAge() );
   }
} 

Following two important points should be noted about the main program −

• The first step is to create a factory object where we used the framework APIXmlBeanFactory() to create the factory bean andClassPathResource() API to load the bean configuration file available in CLASSPATH. The XmlBeanFactory() API takes care of creating and initializing all the objects, i.e. beans mentioned in the configuration file.

• The second step is used to get the required bean using getBean() method of the created bean factory object. This method uses bean ID to return a generic object, which finally can be casted to the actual object. Once you have the object, you can use this object to call any class method.

Beans.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:context = "http://www.springframework.org/schema/context"
   xsi:schemaLocation = "http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/context
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">

   <context:annotation-config/>

   <!-- Definition for student bean -->
   <bean id = "student" class = "com.tutorialspoint.Student" autowire="constructor">
      <constructor-arg name = "name" value = "Zara" />

      <!-- try without passing age and check the result -->
      <!-- constructor-arg name = "age"  value = "11"-->
   </bean>

</beans>

Output

Once you are done creating the source and bean configuration files, let us run the application. If everything is fine with your application, it will raise BeanInitializationException exception and print the following error along with other log messages −

Sept 23, 2025 3:01:44 PM org.springframework.context.support.ClassPathXmlApplicationContext refresh
WARNING: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'student' defined in class path resource [Beans.xml]: Unsatisfied dependency expressed through constructor parameter 1: No qualifying bean of type 'java.lang.Integer' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
Exception in thread "main" org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'student' defined in class path resource [Beans.xml]: Unsatisfied dependency expressed through constructor parameter 1: No qualifying bean of type 'java.lang.Integer' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
	at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:804)
	at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:240)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1383)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1222)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:566)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:526)
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:333)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:371)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:331)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:196)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.instantiateSingleton(DefaultListableBeanFactory.java:1206)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingleton(DefaultListableBeanFactory.java:1172)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:1109)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:979)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:619)
	at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:144)
	at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:85)
	at com.tutorialspoint.MainApp.main(MainApp.java:8)
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'java.lang.Integer' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:2280)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1710)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1636)
	at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:912)
	at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:791)
	... 17 more

Next, you can try the above example after removing the comment from 'age' property as follows −

Beans.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:context = "http://www.springframework.org/schema/context"
   xsi:schemaLocation = "http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/context
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">

   <context:annotation-config/>

   <!-- Definition for student bean -->
   <bean id = "student" class = "com.tutorialspoint.Student" autowire="constructor">
      <constructor-arg name = "name" value = "Zara" /> 
      <constructor-arg name = "age"  value = "11" />
   </bean>

</beans>

The above example will produce the following result −

Name : Zara
Age : 11