Three classes extends an interface then how we can autowire one of these class in another class?

[Vishal Bhadur Verma]

Hi All,

In a recent interview I was being asked a question which confused me ;

Three classes extends an interface then how we can autowire one of these class in another class?

Anybody can hep me on this.

Regards
Jang

[Tim Cooke]

What was your answer to the question? What was your reasoning?

[Vishal Bhadur Verma]

Tim Cooke wrote:What was your answer to the question? What was your reasoning?

I answered him I can autowire this normally as I do usually. No special case in this. For example:

public interface Interface {

public void print();

}

------------------------------

public class Country implements Interface{

public String country_Name;
Capital captial;



public String getCountry_Name() {
return country_Name;
}
public void setCountry_Name(String country_Name) {
this.country_Name = country_Name;
}
public Capital getCaptial() {
return captial;
}
public void setCaptial(Capital captial) {
this.captial = captial;
}
@Override
public void print() {
System.out.println("Msg in Country Class");

}



}

-------------------------------------------------------

ublic class Capital implements Interface {

public String capital_Name;

public String getCapital_Name() {
return capital_Name;
}

public void setCapital_Name(String capital_Name) {
this.capital_Name = capital_Name;
}

@Override
public void print() {
System.out.println("Msg print in Capital Class");

}



}

-----------------------------

Application Context XML

<bean id="country" class="com.test.autowiring.Country" autowire="byName">
<property name="country_Name" value="India"></property>
</bean>

<bean id="captial" class="com.test.autowiring.Capital">
<property name="capital_Name" value="Delhi"></property>
</bean>


-----------------------------------------

Main Class :


public class TestAutowireClass {

/**
* @param args
*/
public static void main(String[] args) {
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("ApplicationContext.xml");
Country con = (Country) applicationContext.getBean("country");
System.out.println("The captial of :"+con.getCountry_Name()+" is :"+con.getCaptial().getCapital_Name());
con.print();

}

}


--------------------------------

Output is ::

The captial of :India is elhi
Msg in Country Class


But he said I should read more on this. I am not sure that I was right or not

[Tim Cooke]

I think what your interviewer was getting at is more like this scenario:

public interface Country { }
public class Ireland implements Country { }
public class England implements Country { }
public class Wales implements Country { }

When you want to populate the dependency in another class.

public class RugbyTeam {
  private Country country;
  // Constructor, Setters, and getters omitted.
}

How do you use Spring's Autowire feature to specify what implementation of Country gets injected?

[Vishal Bhadur Verma]

Tim Cooke wrote:I think what your interviewer was getting at is more like this scenario:

public interface Country { }
public class Ireland implements Country { }
public class England implements Country { }
public class Wales implements Country { }

When you want to populate the dependency in another class.

public class RugbyTeam {
  private Country country;
  // Constructor, Setters, and getters omitted.
}

How do you use Spring's Autowire feature to specify what implementation of Country gets injected?

ooh Got it.. I can use @Qualifier tag in this case
But all three beans will declared individually in application context with different bean id .. Right ?

[Tim Cooke]

Correct.