Below diagram will make it clear:

For example:
1.Country.java:
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package org.arpit.java2blog; public class Country { String countryName; Capital capitalObj; public String getCountryName() { return countryName; } public void setCountryName(String countryName) { this.countryName = countryName; } public Capital getCapitalObj() { return capitalObj; } public void setCapitalObj(Capital capitalObj) { this.capitalObj = capitalObj; } } |
2.Capital.java
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package org.arpit.java2blog; public class Capital { String capitalName; public String getCapitalName() { return capitalName; } public void setCapitalName(String capitalName) { this.capitalName = capitalName; } } |
3.BeanAutowiringByTypeMain.java
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package org.arpit.javapostsforlearning; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class BeanAutowiringByTypeMain{ public static void main(String[] args) { ApplicationContext appContext = new ClassPathXmlApplicationContext("ApplicationContext.xml"); Country countryObj = (Country) appContext.getBean("country"); String countryName=countryObj.getCountryName(); String capitalName=countryObj.getCapitalObj().getCapitalName(); System.out.println(capitalName+" is capital of "+countryName); } } |
4.ApplicationContext.xml
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<?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:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"> <bean id="country" class="org.arpit.java2blog.Country" autowire="byType"> <property name="countryName" value="India"/> </bean> <bean id="capital" class="org.arpit.java2blog.Capital"> <property name="capitalName" value="Delhi" /> </bean> </beans> |
5.Run it
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Delhi is capital of India |
What if two properties of class have same datatype:
Change ApplicationContext.xml as below:
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<?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:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"> <bean id="country" class="org.arpit.java2blog.Country" autowire="byType"> <property name="countryName" value="India"/> </bean> <bean id="capital1" class="org.arpit.java2blog.Capital"> <property name="capitalName" value="Delhi1" /> </bean> <bean id="capital2" class="org.arpit.java2blog.Capital"> <property name="capitalName" value="Delhi2" /> </bean> </beans> |
In above xml, we have declared two capital beans,now how it will autowire.
Answer: It won’t.
When you run above program, it will give you below exception:
It will give you below exception.
