add.java

学生信息管理系统

package homework;
import homework.command;
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 add implements command
{
  private Vector pre_list1=new Vector();
  private Vector pre_list2=new Vector();
  public add()
  {
  }
  public void execute()
  {
    int i;
    stu tempstu = new stu();
    pre_list1=(Vector)stulist.clone();
     stu student;
     do
     {
      student = new stu();
      student.input();
      if(!student.getName().equals("x"))
       stulist.addElement(student);
      } while (!student.getName().equals("x"));
  }
  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);
     }
  }
}