import java.util.*;
public class Room  
{ 
public static void main(String args[]) 
 { 
    ArrayList list = new ArrayList();
    for(int i=1;i<10;i++)
     {
        list.add(i+"");
     }
        int j=1;int k=0;
    while(list.size()>1)
     {
            
            if(k>=list.size())
            {
                k=0;
            }
            if(j==5)
            {
                System.out.print(list.get(k)+"-");
                list.remove(k);
                j=0;
                k--;
            }
            j++;
            k++;
    }
    System.out.println(list.get(0));
 } 

 
}

class er  
{  
public static void main(String[] args)  
{  
StringBuffer x=new StringBuffer("123456789");  
int index = 0;  



for(int i = 0; x.length() > 1/*改了这里*/;i++)  
{  



if(i == 4)  
{  
    //x.delete(index-1,index);    
    x.deleteCharAt(index); //改了这里
    i=0;  
    System.out.println(x); 

}


index++; 
if(index>=x.length() )  //改了这里
    index = 0;   

}  

System.out.println("最后一个数：" + x); 

}
}

约瑟夫环问题，很经典的，我来个HashMap的来实现这个的，效率怎么样，看你要做什么了：
package test02;

import java.io.*;
import java.util.*;

public class ChoosePerson {
    private int n;
    private int flag;

    public ChoosePerson() {
        this.initialization();    
    }
    
   private void  initialization(){
           boolean f = true;
           while(f){
            System.out.print("请输入总人数:");
            try{
                n = input();
            }catch(IOException ae){
                ae.printStackTrace();
                continue;
            }catch(NumberFormatException be){
                be.printStackTrace();
                continue;
            }
            f = false;
        }
        
        f = true;
        
        while(f){
            System.out.print("输入出圈时报到的数字:");
            try{
                flag = input();
            }catch(IOException ae){
                ae.printStackTrace();
                continue;
            }catch(NumberFormatException be){
                be.printStackTrace();
                continue;
            }
            f = false;
        } 
   }
    
   public static int input() throws IOException,NumberFormatException{
        int n = 0;
        InputStreamReader ir = new InputStreamReader(System.in);
        BufferedReader br = new BufferedReader(ir);
        n = Integer.parseInt(br.readLine());
        return n;
    }
    
    public void choose(){
        LinkedHashMap<Integer,String> lhmp = new LinkedHashMap<Integer,String>();
        String s = null;
        for(int i = 0 ; i < n ; i++){
            s = "第" + (i+1) + "号";
            lhmp.put(i , s);
        }
        
        Object[] num = lhmp.keySet().toArray();
        int count = 0;
        int order = 1;
        System.out.println("将这些人分别标记为1-" + n +"号,依次出列的情况如下:");
        while(lhmp.size() != 1){    
            for(int i = 0 ; i < num.length ; i++){
                count++;
                if(count % flag == 0){
                    if(order < 10){
                        System.out.println("第 " + (order++) + "个出列的人 : " 
                            + lhmp.get(num[i]));
                    }
                    else
                        System.out.println("第" + (order++) + "个出列的人 : " 
                            + lhmp.get(num[i]));
                    lhmp.remove(num[i]);
                }
            }
            num = lhmp.keySet().toArray();        
        }
        System.out.println("最后剩下的人为 : " + lhmp.get(num[0]));    
    }
    
    /**
     * @param args
     */
    
     public static void main(String[] args){
        ChoosePerson c = new ChoosePerson();
        c.choose();
    }
            
}