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@Autowired required property in Spring Framework with Example
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Below is an example of "@Autowired required property in Spring Framework with Example"
Step.1 Start a Java Project with required jars 
  1. Open Eclipse
  2. Click on menu New -> Others
  3. In wizards type "Java Project" and Select "Java Project"
  4. Click Next
  5. Enter project name as "AutowiringBeanAsOptionalRequired", then click Next
  6. Goto Libraries tab, then click on Add External JARs, then select Spring's 21 Framework Jars and commons-logging-1.1.jar.
  7. Click Finish.
Step.2 Project Explorer Preview 
RunMyProgram.java
package com.springexample;

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

public class RunMyProgram {
	public static void main(String[] args) {
		ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
		StudentHolder studentHolder = (StudentHolder) context.getBean("studentHolder");
			studentHolder.displayStudentDetails();
	}
}
StudentHolder.java
package com.springexample;

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

public class StudentHolder {
	
	/* Autowired annotation wires the property byType by default */
	@Autowired(required=false)
	Student student;
	
	public Student getStudent() {
		return student;
	}

	public void setStudent(Student student) {
		this.student = student;
	}	
	
	public void displayStudentDetails(){
		System.out.println("Student Details");
		System.out.println("---------------");
		if (student != null){
			System.out.println("Student No: "+student.getStudentNo());
			System.out.println("Student Name: "+student.getStudentName());
		}
		else {
			System.out.println("Student Object reference not found!");
		}
		
	}
}
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">

	<bean id="studentHolder" class="com.springexample.StudentHolder" />
	<context:annotation-config />
</beans>
Student.java
package com.springexample;

public class Student {
	private int studentNo;
	private String studentName;
	
	public int getStudentNo() {
		return studentNo;
	}
	public void setStudentNo(int studentNo) {
		this.studentNo = studentNo;
	}
	public String getStudentName() {
		return studentName;
	}
	public void setStudentName(String studentName) {
		this.studentName = studentName;
	}	
}
Output 
Student Details
---------------
Student Object reference not found!
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AutowiringBeanAsOptionalRequired

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