Spring config file

package com.luv2code.springdemo;

public interface Coach {

    public String getDailyWorkout();

    public String getDailyFortune();

}

package com.luv2code.springdemo;

public interface FortuneService {

    public String getFortune();
}
package com.luv2code.springdemo;

public class BaseballCoach implements Coach {

    // define a private field for the dependency
    private FortuneService fortuneService;

    // define a constructor dependency injection
    public BaseballCoach(FortuneService fortuneService) {
        this.fortuneService = fortuneService;
    }

    @Override
    public String getDailyWorkout() {
        return "Spend 30 minutes on batting practice";
    }

    @Override
    public String getDailyFortune() {
        // use my fortuneService to get a fortune
        return fortuneService.getFortune();
    }
}
<?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.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">

    <!-- define the dependency -->
    <bean id="myFortune" class="com.luv2code.springdemo.HappyFortuneService">
    </bean>

    <bean id="myCoach" class="com.luv2code.springdemo.BaseballCoach">
    <!-- set up constructor injection -->
        <constructor-arg ref="myFortune"/>
    </bean>

</beans>
What happens behind the scenes?
Spring creates objects of beans:
HappyFortuneService myFortune = new HappyFortuneService();
BeseballCoach myCoach = new BaseballCoach(myFortune);