为什么采购（UpdateBtn）按钮调用不了方法

Question

package jiemian;import java.awt.*;import java.awt.event.*;import javax.swing.*;import java.sql.*;public class BookPurchase extends JFrame implements ActionListener{ JPanel panel1,panel2,panel3,panel4; JLabel TipLabel=new JLabel("我们来看看仓库里有没有这本书呢"); JLabel BookNameLabel,PressNameLabel,       AuthorLabel,BookIdLabel,       PressDateLabel,PriceLabel,StationLabel; JTextField BookNameTextField,PressNameTextField,           AuthorTextField,BookIdTextField,           PressDateTextField,PriceTextField,StationTextField; Container c; JButton ClearBtn,YesBtn,UpdateBtn/*,ExitBtn*/; public BookPurchase() { super("图书采购"); c=getContentPane(); c.setLayout(null); panel3=new JPanel(); panel3.add(TipLabel); panel3.setBounds(0,0,300,30); c.add(panel3,BorderLayout.NORTH); BookIdLabel=new JLabel("编号",JLabel.CENTER); BookNameLabel=new JLabel("书名",JLabel.CENTER); AuthorLabel=new JLabel("作者",JLabel.CENTER); PressNameLabel=new JLabel("出版社",JLabel.CENTER); PressDateLabel=new JLabel("采购数量",JLabel.CENTER); PriceLabel=new JLabel("采购价格",JLabel.CENTER); StationLabel=new JLabel("采购金额",JLabel.CENTER); BookNameTextField=new JTextField(20); PressNameTextField=new JTextField(20); AuthorTextField=new JTextField(20); BookIdTextField=new JTextField(20); PressDateTextField=new JTextField(20); PriceTextField=new JTextField(20); StationTextField=new JTextField(15); panel1=new JPanel(); panel4=new JPanel(); panel1.setLayout(new GridLayout(7,1)); panel4.setLayout(new GridLayout(7,1)); panel1.add(BookIdLabel); panel4.add(BookIdTextField); panel1.add(BookNameLabel); panel4.add(BookNameTextField); panel1.add(PressNameLabel); panel4.add(PressNameTextField); panel1.add(AuthorLabel); panel4.add(AuthorTextField); panel1.add(PressNameLabel); panel4.add(PressNameTextField); panel1.add(PressDateLabel); panel4.add(PressDateTextField); panel1.add(PriceLabel); panel4.add(PriceTextField); panel1.add(StationLabel); panel4.add(StationTextField); panel1.setBounds(0,30,100,220); panel4.setBounds(100,30,220,220); panel2=new JPanel(); panel2.setBounds(10,260,300,30); panel2.setLayout(new GridLayout(1,4)); ClearBtn=new JButton("清空"); YesBtn=new JButton("查询"); UpdateBtn=new JButton("采购"); //ExitBtn=new JButton("计算"); panel2.add(ClearBtn); panel2.add(YesBtn); panel2.add(UpdateBtn); //panel2.add(ExitBtn); ClearBtn.addActionListener(this); YesBtn.addActionListener(this); UpdateBtn.addActionListener(this); //ExitBtn.addActionListener(this); //UpdateBtn.setEnabled(false); c.add(panel3); c.add(panel1); c.add(panel4); c.add(panel2); setVisible(true); setBounds(100,50,330,320); } public void actionPerformed(ActionEvent e) { Connection con;        PreparedStatement sql;        ResultSet rs; if(e.getSource()==ClearBtn) { BookNameTextField.setText(""); PressNameTextField.setText(""); AuthorTextField.setText(""); BookIdTextField.setText(""); PressDateTextField.setText(""); PriceTextField.setText(""); StationTextField.setText(""); } else if(e.getSource()==YesBtn) { try {  Class.forName("com.mysql.jdbc.Driver");            }     catch(ClassNotFoundException f){}      try {               String Id;             Id=BookIdTextField.getText();             con=DriverManager.getConnection("jdbc:mysql://127.0.0.1:3306/book","root","123456");              sql=con.prepareStatement("SELECT * FROM essential where Id=?");              sql.setString(1,Id);              rs=sql.executeQuery();              if(!rs.next()){              JOptionPane.showMessageDialog(this,"这本书我们仓库没有，老板","提示对话框",JOptionPane.WARNING_MESSAGE);                 }              else{             JOptionPane.showMessageDialog(this,"老板这本书我们有了，买不买你说了算","提示对话框",JOptionPane.WARNING_MESSAGE);              }      }      catch(SQLException e2)          {  System.out.println(e2);        }      if(e.getSource()==UpdateBtn){      if(BookIdLabel.getText().trim().equals(""))  {  JOptionPane.showMessageDialog(null,"编号不能为空！");  }  else if(BookNameLabel.getText().trim().equals(""))  {  JOptionPane.showMessageDialog(null,"书名不能为空！");  }  else if(AuthorLabel.getText().trim().equals(""))  {  JOptionPane.showMessageDialog(null,"作者不能为空！");  }  else if(PressNameLabel.getText().trim().equals(""))  {  JOptionPane.showMessageDialog(null,"出版社不能为空！");  }  else if(PressDateLabel.getText().trim().equals(""))  {  JOptionPane.showMessageDialog(null,"采购数量");  }  else if(PriceLabel.getText().trim().equals(""))  {  JOptionPane.showMessageDialog(null,"采购价格不能为空！");  }  else if(StationLabel.getText().trim().equals(""))  {  JOptionPane.showMessageDialog(null,"采购金额不能为空！");  }  else {  int n=JOptionPane.showConfirmDialog(this,"确认要采购吗？老板","确认对话框",JOptionPane.YES_NO_OPTION );              if(n==JOptionPane.YES_OPTION){                            }      else{  /*String SerialPrice,quantity;  Double tamount;  SerialPrice=PriceTextField.getText();  quantity=PressDateLabel.getText();  StationTextField.setText("str");  tamount=Double.parseDouble(SerialPrice)*Double.parseDouble(quantity);  String str = String.valueOf(tamount);*/  UpdateBtn.addMouseListener(new MouseListener(){  public void mouseClicked(MouseEvent e) {  int value1 = Integer.parseInt(PressDateLabel.getText().trim());  int value2 = Integer.parseInt(PriceLabel.getText().trim());    StationLabel.setText(String.valueOf(value1 + value2));  }  public void mouseEntered(MouseEvent e) {  // TODO Auto-generated method stub    }  public void mouseExited(MouseEvent e) {  // TODO Auto-generated method stub    }  public void mousePressed(MouseEvent e) {  // TODO Auto-generated method stub    }  public void mouseReleased(MouseEvent e) {  // TODO Auto-generated method stub    }    });  }  }        }                }      } public static void main(String args[]){ new BookPurchase(); } }