delete.java

学生信息管理系统

package homework;
import java.util.*;
///班级：信计 01-2班     学号：01012218     姓名：武冬生

/**
 * Title:
 * Description:
 * Copyright:    Copyright (c) 2004
 * Company:
 * @author
 * @version 1.0
 */

public class delete  implements command
{
   private Vector pre_list1=new Vector();
  private Vector pre_list2=new Vector();
  public delete()
  {
  }
  public void execute()
  {
    int i;
    stu tempstu = new stu();
    pre_list1=(Vector)stulist.clone();
   System.out.println("Please input the name to delete:");
   String stuname,name;
   stuname=Keyboard.readString();
   for(i=0;i<stulist.size();i++)
   {
    stu student=(stu)stulist.elementAt(i);
    name=student.getName();
    if(stuname.equals(name))
     break;
    }
  if(i<stulist.size())
    stulist.removeElementAt(i);
    else
   System.out.println("There is no this student:"+stuname);
  }
  public void undo()
  {
    stu tempstu=new stu();
    pre_list2=(Vector)stulist.clone();
    stulist.clear();
    for (int i = 0; i < pre_list1.size(); i++)
    {
     tempstu = (stu) pre_list1.elementAt(i);
     stulist.add(tempstu);
     }
  }
  public void redo()
  {
    stu tempstu=new stu();
    stulist.clear();
    for (int i = 0; i < pre_list2.size(); i++)
    {
     tempstu = (stu) pre_list2.elementAt(i);
     stulist.add(tempstu);
     }
  }
}