java 输入回车有关问题_J2SE

java 输入回车问题
Scanner s=new Scanner(System.in); //输入数据
Random random=new Random(); //产生随机数
int [] guessNumber=new int[4]; //保存玩家输入的数

for(int i=0;i<4;i++)
{
guessNumber[i]=s.nextInt();
}
我想如果在循环里，输入回车的时候执行某个命令，怎么写？？不懂呀！！初学java，请大家帮忙哈！谢谢了！！

------解决方案--------------------------------------------------------
哦哦原来楼主是这个意思啊，

Java code

import java.util.Scanner;public class Test{    static int[] guessNumber = new int[4]; // 保存玩家输入的数    static Scanner s;    static int i;    public static void main(String[] args)    {        w();    }    public static void w()    {            System.out.println("输入结束请按回车然后ctrl+z");                StringBuffer sb = new StringBuffer();                s = new Scanner(System.in);                while (s.hasNext())        {            sb = sb.append(s.next() + " ");        }                if (4 != sb.toString().split(" ").length)        {            System.out.println("输入不正确");        }        else        {            System.out.println("输入正确");                        for (int i = 0; i < 4; i++)            {                guessNumber[i] = Integer.parseInt(sb.toString().split(" ")[i]);            }                        System.out.print("数组内容为:  ");                        for (int number : guessNumber)            {                System.out.print(number + " ");            }        }    }}
------解决方案--------------------------------------------------------
经我测试了可以。。。  
package task;
import java.util.Scanner;

public class Panduan{

   static int[] guessNumber = new int[4]; // 保存玩家输入的数
  
   public static void main(String[] args)
   {
       w();
   }

   public static void w()
   {   
   	Scanner s = new Scanner(System.in);

       System.out.println("情输入四个数，按回车结束！");
  	 String  str = new String();
    str = s.nextLine();
       String str1[] = new String[4];
       str1 = str.split(" ");
      
       if (4 != str1.length)
       {
           System.out.println("请输入四个数！");
           return;
       }
       else
       {
           System.out.println("输入正确");
           String str2 ="";
          
           for (int i = 0; i < 4; i++)
           {
           	str2+=str1[i];
           }
           System.out.print("数组内容为:  "+str2);
         

       }
   }
}