import java.util.*;
class Student //定义一个类
{
    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();
  /*将有的对象添加到数组里面*/
  Student stu1 = new Student();
        stu1.setStu("张","张三");
        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("张","张磊");
        a.add(stu5);
            
        Student stu6 = new Student();
        stu6.setStu("张","张武");
        a.add(stu6);
            
        Student stu7 = new Student();
        stu7.setStu("张","张杰");
        a.add(stu7);
            
        Student stu8 = new Student();
        stu8.setStu("王","王石");
        a.add(stu8);

        while(true) {
         System.out.println("a:加法   b:输出当前日期   c:查找姓名  q是退出");
            System.out.print("请输入字母: ");
         String s = sc.next();
         if(s.equals("a"))
         {
    System.out.print("请输入第一个数:");//读取下面一样
    int m=sc.nextInt();
    System.out.print("请输入第二个数:");
    int n=sc.nextInt();
    int he=m+n;
    System.out.println("它们的和为:"+he);
         }
         if(s.equals("b"))
         {
          int Y,M,D,H,m,S;
        Y = Calendar.getInstance().get(Calendar.YEAR);//调用年份方法
             M = Calendar.getInstance().get(Calendar.MONTH);//调用月份方法
             D = Calendar.getInstance().get(Calendar.DAY_OF_MONTH);//调用天份方法
            H = Calendar.getInstance().get(Calendar.HOUR_OF_DAY);//调用方法
            m = Calendar.getInstance().get(Calendar.MINUTE);//调用方法
             S = Calendar.getInstance().get(Calendar.SECOND);
             System.out.println("当前系统时间为：" + Y + "年" + (M+1) + "月" + D +"日" + H+"点"+m + "分"+S+ "秒");
             System.out.println();
         }
         if(s.equals("c"))
         {  
          System.out.print("请输入姓名: ");
          String name = sc.next();
    //System.out.println(name.length());这是看看它的长度
          if(name.length()==2) //字节来限制
          {
              Iterator it = a.iterator(); // 迭代导引
        while(it.hasNext())
              {
                  Student h = (Student)it.next();//转化为Student对象
       if(h.xingming.equals(name))
      {
          h.printStudent();
      }
         }
          }
          if(name.length()==1) //字节来限制
          {
              Iterator it = a.iterator();  
              while(it.hasNext())
              {
       Student h = (Student)it.next();//转化为Student对象
      if(h.xing.equals(name))
            {
                h.printStudent();
  
            }
   
         } 
          }
          }
          if(s.equals("q"))
          {
           break;
          }
        }
    }
}
这是程序的全部,有点简陋请大家不见笑，请多多指教。