Java方法覆盖参数“Class <？ extends Object>“

Question

I got a problem with java when i try to override a method,my code is following:

public abstract class CustomAdapter{
    public abstract Boolean addItem(Class<? extends Object> aObject);
}

public class RainAdapter extends CustomAdapter {
    @Override
    public Boolean addItem(ClassOfRain aRainInfo) {
        // do something
    return true;
    }
}

Can I declare the the "Class" to "ClassOfRain"? If yes,how to do?

Thanks for your reading!

Answer 1

I think you are a bit confused. Are you sure you are not trying to say:

public abstract class CustomAdapter<T extends Object> {
    public abstract Boolean addItem(T aObject);
}

public class RainAdapter extends CustomAdapter<Rain> {
    @Override
    public Boolean addItem(Rain aRainInfo) {
        // do something
        return true;
    }
}

In my interpretation of your class structure, you are trying to make a generic addItem method, so passing around the actual class object is of no use.

Answer 2

That is not possible. A method override means that you put exactly the same method header. Only thing you can change is the name of the given parameter.

Answer 3

Class<Rain.class> would hold the reflection of Rain class. But this will not work, because overridden methods must have the same formal parameters, so you'll have to use Class<? extends Object> Class<? extends Object> .

Answer 4

the method signatures must match when implementing abstract/interface methods and/or overwriting ... you could do something like this tho

public abstract class CustomAdapter{
    public abstract Boolean addItem( Object o );
}

public class RainAdapter extends CustomAdapter {

    public Boolean addItem( Object o ){
        if ( o.getClassName().equals( "ClassOfRain" ) ){
            return this.addItem( (ClassOfRain) o );
        }
        return false;
    }
    private Boolean addItem(ClassOfRain aRainInfo) {
        // do something
        return true;
    }
}