example11_5.java

书中的例题

/* 学生成绩表  */ 
 import java.util.*;
class Student  
{
  int english=0;
  String  name,number;
  Student(String na,String nu,int e)
   {
	 english=e;
	 name=na;
	 number =nu;
   }
}
public class Example11_5
{
  public static void main(String args[])
  {
   Hashtable hashtable=new Hashtable();
   hashtable.put("20060301",new Student("20060301","张三",91));
   hashtable.put("20060302",new Student("20060302","李四",82));
   hashtable.put("20060303",new Student("20060303","陶万三",93));
   hashtable.put("20060304",new Student("20060304","忽必烈",46));
   hashtable.put("20060305",new Student("20060305","许士林",77));
   hashtable.put("20060306",new Student("20060306","谢小傅",55));
   Student stu=(Student)hashtable.get("20060302");//检索一个数据项。 
   System.out.println(stu.number+"  "+stu.name+"  "+stu.english);
   hashtable.remove("20060306"); //删除一个元素
   System.out.println("哈希表中现在含有："+hashtable.size()+"个元素");
   Enumeration enum1=hashtable.elements(); 
   while(enum1.hasMoreElements())   //遍历当前哈希表。
    {
	  Student s=(Student)enum1.nextElement();
      System.out.println(s.number+"  "+s.name+"  "+s.english);
    }
  }     
}