Question

I’ve a base class with a property that should be set in the derived class. I’ve to use annotations. How’s that possible?
I know how do this with xml spring configurations, but not with annotations, because I’ve to write them at the property?

Here’s some example code:

public class Base {
    // This property should be set
    private String ultimateProperty;

    // ....
}

public class Hi extends Base {
    // ultimate property should be "Hi" in this class
    // ...
}

public class Bye extends Base {
    // ultimate property should be "Bye" in this class
    // ...
}

How is this possible with annotations?

Answer 1

Some options depending on what else Base has:

class Base {
    private String ultimateProperty;

    Base() {
    }

    Base(String ultimateProperty) {
        this.ultimateProperty = ultimateProperty;
    }

    public void setUltimateProperty(String ultimateProperty) {
        this.ultimateProperty = ultimateProperty;
    }
}

class Hi extends Base {
    @Value("Hi")
    public void setUltimateProperty(String ultimateProperty) {
        super.setUltimateProperty(ultimateProperty);
    }
}

class Bye extends Base {
    public Bye(@Value("Bye") String ultimateProperty) {
        setUltimateProperty(ultimateProperty);
    }
}

class Later extends Base {
    public Later(@Value("Later") String ultimateProperty) {
        super(ultimateProperty);
    }
}

class AndAgain extends Base {
    @Value("AndAgain")
    private String notQuiteUltimate;

    @PostConstruct
    public void doStuff() {
        super.setUltimateProperty(notQuiteUltimate);
    }
}

Of course, if you really just want the name of the class there, then

class SmarterBase {
    private String ultimateProperty = getClass().getSimpleName();
}