Exception in thread"main"java.lang.ClassCastException: thepvc cannot be cast to

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class Thepvc extends Frame
implements WindowListener
{
        /**
 * 
 */
private static final long serialVersionUID = 1L;
Button design,open1,open2,reset;
TextArea text;
        Box   basebox ,box1,box2, box3;
        FileDialog  filedialog_load;//声明两个文件对话框
        Thepvc()
        {  
           design=new Button("设计");
           open1=new Button("打开");
           open1.addActionListener((ActionListener) this);
           open2=new Button("打开");
           open2.addActionListener((ActionListener) this);
           filedialog_load=new FileDialog(this ,"打开文件对话框",FileDialog.SAVE);
           filedialog_load.addWindowListener(new WindowAdapter()
           {
            public void windowClosing(WindowEvent e)
            {
            filedialog_load.setVisible(false);
            }
           });
           reset=new Button("复位");
           box1=Box.createVerticalBox();
           box1.add(new Label("第一步 导入人员资料  "));
           box1.add(Box.createVerticalStrut(2));
           box1.add(new Label("第二步 选择照片位置  "));
           box1.add(Box.createVerticalStrut(2));
           box1.add(new Label("进行证卡验证"));
           box2=Box.createVerticalBox();
           box2.add(new TextField(30));
           box2.add(Box.createVerticalStrut(2));
           box2.add(new TextField(30));
           box2.add(Box.createVerticalStrut(2));
           box2.add(design);
           box3=Box.createVerticalBox();
           box3.add(open1);
           box3.add(Box.createVerticalStrut(2));
           box3.add(open2);
           box3.add(Box.createVerticalStrut(2));
           box3.add(reset); 
           basebox=Box.createHorizontalBox();
           basebox.add(box1);
           basebox.add(Box.createHorizontalStrut(2));
           basebox.add(box2);
           basebox.add(Box.createHorizontalStrut(2));
           basebox.add(box3);
           basebox.add(text);
           text=new TextArea(12,12);
           add(basebox); 
           setLayout(new FlowLayout());
           setBounds(0,0,600,600);   
           setVisible(true);       
           addWindowListener(this);
           validate();
          
  
            
        }
        public void actionPerformed(ActionEvent e)
        {
         if(e.getSource()==open1||e.getSource()==open2)
         {
         filedialog_load.setVisible(true);
         String name=filedialog_load.getFile();
         if(name!=null)
         {
         text.setText("");
         }
         }
        }
        public void windowActivated(WindowEvent e)
        {
             
        }
        public void windowDeactivated(WindowEvent e)
        {                  setBounds(0,0,400,400);
                 validate();
             
        }
        public void windowClosing(WindowEvent e)
       {
                   dispose();
       }
       public void windowClosed(WindowEvent e)
       {
            System.exit(0);
       }
       public void windowIconified(WindowEvent e)
       {
       }
       public void windowDeiconified(WindowEvent e)
       {
                setBounds(0,0,400,400);
                validate();
       }
       public void windowOpened(WindowEvent e){}
 }
      public class Thepv
    {
           public static void main(String args[])
           {
                 Thepvc thepvc=new Thepvc();
            }
    }