Java - 29

interface Processor {

    void processTask(String task);
}

class AMD implements Processor {
    public void processTask(String task) {

    }
}

class Intel implements Processor {
    public void processTask(String task) {

    }
}

abstract class Device {
    public abstract String getTask();
    void switchOn() {

    }
}

class Computer extends Device {
    public String getTask() {
        return "Useful gadget :D";
    }
}

class Mobile extends Device {
    public String getTask() {
        return "Mobile device :)";
    }
}