import java.util.*;
class Student //定義一個類
{
    String xing;
    String xingming;
    void setStu(String xing1,String xingming1)
    {
     xing = xing1;
     xingming = xingming1;
    }
    void printStudent()
    {
     System.out.println(xingming);
    }
    public String toString()
    {
     return xing+" "+xingming;
 }
 }
class YongHu {
    public static void main(String args[])
   {
        Scanner sc = new Scanner(System.in);
        ArrayList a = new ArrayList();
     Student stu = new Student();
  /*將有的對象添加到數組里面*/
  Student stu1 = new Student();
        stu1.setStu("張","張三");
        a.add(stu1);
          
        Student stu2 = new Student();
        stu2.setStu("李","李四");
             a.add(stu2);
            
        Student stu3 = new Student();
        stu3.setStu("王","王五");
        a.add(stu3);
            
        Student stu4 = new Student();
        stu4.setStu("李","李旺");
        a.add(stu4);
            
        Student stu5 = new Student();
        stu5.setStu("張","張磊");
        a.add(stu5);
            
        Student stu6 = new Student();
        stu6.setStu("張","張武");
        a.add(stu6);
            
        Student stu7 = new Student();
        stu7.setStu("張","張杰");
        a.add(stu7);
            
        Student stu8 = new Student();
        stu8.setStu("王","王石");
        a.add(stu8);

        while(true) {
         System.out.println("a:加法   b:輸出當前日期   c:查找姓名  q是退出");
            System.out.print("請輸入字母: ");
         String s = sc.next();
         if(s.equals("a"))
         {
    System.out.print("請輸入第一個數:");//讀取下面一樣
    int m=sc.nextInt();
    System.out.print("請輸入第二個數:");
    int n=sc.nextInt();
    int he=m+n;
    System.out.println("它們的和為:"+he);
         }
         if(s.equals("b"))
         {
          int Y,M,D,H,m,S;
        Y = Calendar.getInstance().get(Calendar.YEAR);//調用年份方法
             M = Calendar.getInstance().get(Calendar.MONTH);//調用月份方法
             D = Calendar.getInstance().get(Calendar.DAY_OF_MONTH);//調用天份方法
            H = Calendar.getInstance().get(Calendar.HOUR_OF_DAY);//調用方法
            m = Calendar.getInstance().get(Calendar.MINUTE);//調用方法
             S = Calendar.getInstance().get(Calendar.SECOND);
             System.out.println("當前系統時間為：" + Y + "年" + (M+1) + "月" + D +"日" + H+"點"+m + "分"+S+ "秒");
             System.out.println();
         }
         if(s.equals("c"))
         {  
          System.out.print("請輸入姓名: ");
          String name = sc.next();
    //System.out.println(name.length());這是看看它的長度
          if(name.length()==2) //字節來限制
          {
              Iterator it = a.iterator(); // 迭代導引
        while(it.hasNext())
              {
                  Student h = (Student)it.next();//轉化為Student對象
       if(h.xingming.equals(name))
      {
          h.printStudent();
      }
         }
          }
          if(name.length()==1) //字節來限制
          {
              Iterator it = a.iterator();  
              while(it.hasNext())
              {
       Student h = (Student)it.next();//轉化為Student對象
      if(h.xing.equals(name))
            {
                h.printStudent();
  
            }
   
         } 
          }
          }
          if(s.equals("q"))
          {
           break;
          }
        }
    }
}
這是程序的全部,有點簡陋請大家不見笑，請多多指教。