接口
一个简单例子
public class Interface01 {
    public static void main(String[] args) {
        Camera camera = new Camera();
        Phone phone = new Phone();
        Computer computer = new Computer();
        computer.work(camera);
        computer.work(phone);
    }
}
public interface UsbInterface {
    public void start();
​
    public void stop();
}
public class Phone implements UsbInterface {
  ...