j2se 用友面试题

/**
 * 
 */
package com.java;

/**
 * @author Administrator
 *
 */
public class TestA {

	interface An{
		void sayHi();
		String getName();
	}
	
	class Dog implements An{
		public String getName()
		{
			return "Bob";
		}
		public void sayHi()
		{
			System.out.println("I am " + getName() + "." +back());
		}
		private String back()
		{
			return "wang-wang";
		}
	}
	
	class BullDog extends Dog{
		public String getName()
		{
			return "Mike";
		}
		private String back()
		{
			return "WOO-WOO";
		}
	}
	
	public void checkout()
	{
		An a = new Dog();
		a.sayHi();
		
		An b = new BullDog();
		b.sayHi();
		
		Dog dog = new Dog();
		check(dog);
		
		BullDog bulldog = (BullDog)b;
		check(bulldog);
	}
	
	public void check(Dog dog)
	{
		System.out.println("check dog "+dog.getName());
	}
	public void check(BullDog bulldog)
	{
		System.out.println("check dog "+bulldog.getName());
	}
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		TestA tA = new TestA();
		tA.checkout();
	}

}

 

 

结果：

I am Bob.wang-wang
I am Mike.wang-wang
check dog Bob
check dog Mike