Java用特定类型扩展超类的泛型方法

Question

Say I have the following interface:

public interface Renderer {
...
    public <T> void setBackingGraphics(T t);
}

How do I now implement the interface in a way that specifies what specific "T" to use?

@Override
public <Graphics> void setBackingGraphics(Graphics t) {
    ...
}

The above obviously doesn't work because "Graphics" will just be considered to be another placeholder. How do I actually make it "usable"? Let me demonstrate what I mean by using generic classes as example:

public interface A<T> {
    T someT();
}
public class C extends A<B> {
    B someT(){...}
}

How does the above work if I only want to apply it to specific methods?

Answer 1

You need to be able to call the Renderer setBackingGraphics with any Object so the only thing you can do is:

@Override
public void setBackingGraphics(Object t) {
}

If you want something more specific you need to bound your parameter, for example:

public interface Renderer {
    public <T extends String> void setBackingGraphics(T t);
}

And then you can do:

@Override
public void setBackingGraphics(String t) {
}