小狗在不同环境条件下可能呈现不同的状态表现，要求用接口封装小狗的状态。

代码如下：

interface DogState{public void showState();
}class SoftlyState implements DogState {public void showState(){System.out.println("听主人的命令！");}
}class MeetEnemyState implements DogState {public void showState(){System.out.println("上去咬一口！");}
}class MeetFriendState implements DogState {public void showState(){System.out.println("晃动尾巴，以示友好！");}
}class MeetAnotherDog implements DogState {public void showState(){System.out.println("hello！");}
}class Dog{DogState state;public void show(){state.showState();}public void setState(DogState s){state=s;}
}public class CheckDogState{public static void main(String[] args) {Dog yellowDog=new Dog();System.out.println("狗在主人面前：");yellowDog.setState(new SoftlyState());yellowDog.show();System.out.println("狗遇到敌人：");yellowDog.setState(new MeetEnemyState());yellowDog.show();System.out.println("狗遇到朋友：");yellowDog.setState(new MeetFriendState());yellowDog.show();System.out.println("狗遇到同伴：");yellowDog.setState(new MeetAnotherDog());yellowDog.show();}
}