接口是對先有功能的一種擴展. AbstractDog.java ~~~ package 接口; public abstract class AbstractDog { protected String name; protected int age; public abstract void eat(); public abstract void bark(); } ~~~ Detection.java ~~~ package 接口; public interface Detection { void Detection(); } ~~~ DetectionDog.java ~~~ package 接口; public class DetectionDog extends AbstractDog implements Detection { @Override public void eat() { System.out.println("緝毒狗吃"); } @Override public void bark() { System.out.println("緝毒狗叫"); } @Override public void Detection() { System.out.println("緝毒"); } } ~~~