后面这部分我没看懂。能麻烦稍微讲解一下吗？	
> 		boolean dup = false;	
> 		int num = 1;
> 		String first = arr.get(0);
> 		int pointer = 1;
> 		int arrSize = arr.size();
> 		while(pointer < arrSize)
> 		{
> 			if(first.equals(arr.get(pointer)))
> 			{
> 				num += 1;
> 				pointer += 1;
> 				if(pointer == arr.size())
> 				{
> 					dup = true;
> 					System.out.println(first.substring(0,3)+"-"+first.substring(3,7)+" "+num);
> 				}
> 			}
> 			else 
> 			{
> 				if(num > 1)
> 				{
> 					dup = true;
> 					System.out.println(first.substring(0,3)+"-"+first.substring(3,7)+" "+num);
> 				}
> 				num = 1;
> 				first = arr.get(pointer);
> 				pointer += 1;
> 			}
> 		}
> 		if(!dup)
> 			System.out.println("No duplicates.");
> 	}
> }