Program rzuca java.lang.UnsupportedOperationException w Javie

Question

import javax.swing.*; 
    import javax.swing.event.*; 
    import java.awt.*; 
    import java.awt.event.*; 
    import java.sql.*; 
    import java.io.*; 

    public class Student3 extends JFrame implements ActionListener 
    { 
    Connection cn; 
    Statement st1,st2; 
    ResultSet rs; 

    JPanel panel1 = new JPanel(); 
    JPanel panel2 = new JPanel(); 

    JLabel lblNo = new JLabel("Roll No "); 
    JLabel lblName = new JLabel("First Name "); 
    JLabel lblCont = new JLabel("Contect no "); 
    JLabel lblCity = new JLabel("City "); 

    JTextField txtNo = new JTextField(12); 
    JTextField txtName = new JTextField(12); 
    JTextField txtCont = new JTextField(12); 
    JTextField txtCity = new JTextField(12); 

    JButton btnFirst = new JButton("First"); 
    JButton btnNext = new JButton("Next"); 
    JButton btnPrevious = new JButton("Previous"); 
    JButton btnLast = new JButton("Last"); 
    JButton btnAdd = new JButton("Add"); 
    JButton btnUpdate = new JButton("Update"); 
    JButton btnDelete = new JButton("Delete"); 
    JButton btnExit = new JButton("Exit"); 

     Student3() 
     { 
      try 
      { 
       panel1.setLayout(new GridBagLayout()); 

       GridBagConstraints c = new GridBagConstraints(); 

       //c.fill=GridBagConstraints.BOTH; 
       c.gridwidth=2; 
       c.gridx=0; 
       c.gridy=0; 
       panel1.add(lblNo,c); 

       c.gridx=2; 
       c.gridy=0; 
       panel1.add(txtNo,c); 

       c.gridx=0; 
       c.gridy=1; 
       panel1.add(lblName,c); 

       c.gridx=2; 
       c.gridy=1; 
       panel1.add(txtName,c); 

       c.gridx=0; 
       c.gridy=2; 
       panel1.add(lblCont,c); 

       c.gridx=2; 
       c.gridy=2; 
       panel1.add(txtCont,c); 

       c.gridx=0; 
       c.gridy=3; 
       panel1.add(lblCity,c); 

       c.gridx=2; 
       c.gridy=3; 
       panel1.add(txtCity,c); 

       c.fill=GridBagConstraints.BOTH; 
       //c.gridwidth=1; 
       c.gridx=0; 
       c.gridy=5; 
       panel1.add(btnFirst,c); 

       c.gridwidth=1; 
       c.gridx=2; 
       c.gridy=5; 
       panel1.add(btnNext,c); 

       c.gridx=3; 
       c.gridy=5; 
       panel1.add(btnPrevious,c); 

       c.gridx=4; 
       c.gridy=5; 
       panel1.add(btnLast,c); 

       c.gridwidth=2; 
       c.gridx=0; 
       c.gridy=6; 
       panel1.add(btnAdd,c); 

       c.gridwidth=1; 
       c.gridx=2; 
       c.gridy=6; 
       panel1.add(btnUpdate,c); 

       c.gridx=3; 
       c.gridy=6; 
       panel1.add(btnDelete,c); 

       c.gridx=4; 
       c.gridy=6; 
       panel1.add(btnExit,c); 

       getContentPane().add(panel1); 

       btnFirst. addActionListener(this); 
       btnLast. addActionListener(this); 
       btnNext. addActionListener(this); 
       btnPrevious. addActionListener(this); 
       btnAdd. addActionListener(this); 
       btnUpdate. addActionListener(this); 
       btnDelete. addActionListener(this); 
       btnExit. addActionListener(this); 

       Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");//Load the JDBC-ODBC bridge driver 
       cn = DriverManager.getConnection("jdbc:odbc:STUDENT_DSN");//Connection to database is done 

       //st1=cn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE); 
       st1=cn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE,ResultSet.HOLD_CURSORS_OVER_COMMIT); 
       //cn.setHoldability(ResultSet.HOLD_CURSORS_OVER_COMMIT); 
       //st1.setFetchSize(25); 

       st2=cn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE); 


       String query = "select * from Student";   
       rs=st1.executeQuery(query); 
       rs.first(); 
       getRecord(); 
      } 
      catch(Exception e) 
      { 
       System.out.println(e); 
      } 
     } 

     public static void main (String[] args) 
     { 
      Student3 my =new Student3(); 

      my.setTitle("Java Database Operation.."); 
      my.setVisible(true); 
      my.setResizable(false); 
      my.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
      my.setBounds(200,250,300,175); 
     } 

     void getRecord() 
     { 
      try 
      { 
       txtNo.setText(rs.getObject(1).toString()); 
       txtName.setText(rs.getObject(2).toString()); 
       txtCont.setText(rs.getObject(3).toString()); 
       txtCity.setText(rs.getObject(4).toString()); 
      } 
      catch(Exception ex) 
      { 
       System.out.println(ex); 
      } 
     } 

     public void actionPerformed(ActionEvent e) 
     { 
      try 
      { 

       Object obj = e.getSource(); 
       if(obj == btnFirst) 
       { 
        rs.first(); 
        getRecord(); 
       } 
       if(obj == btnLast) 
       { 
        rs.last(); 
        getRecord();     
       } 
       if(obj == btnNext) 
       { 
        rs.next(); 
        if(!rs.isAfterLast()) 
        {    
         getRecord(); 
        } 
        else 
        { 
         rs.previous(); 
        } 
       } 
       if(obj == btnPrevious) 
       { 
        rs.previous(); 
        if(!rs.isBeforeFirst()) 
        {    
         getRecord(); 
        } 
        else 
        { 
         rs.next(); 
        } 
       } 
       if(obj == btnAdd) 
       { 
        String name=txtName.getText(); 

        String cont=txtCont.getText(); 

        String city=txtCity.getText(); 


        String query="insert into Student(sName,sCont,sCity) values ('"+name+"','"+cont+"','"+city+"')" ; 
        st2.executeUpdate(query); 

        query = "select * from Student";    
        rs=st1.executeQuery(query); 

        rs.last(); 
       } 
       if(obj == btnUpdate) 
       { 
        int no =Integer.parseInt(txtNo.getText()); 
        //System.out.println(no); 

        String new_name=txtName.getText(); 

        String new_cont=txtCont.getText(); 

        String new_city=txtCity.getText(); 

        String query="update Student set sName = '"+new_name+"', sCont = '"+new_cont+"' , sCity = '"+new_city+"' where sNo = "+no+" " ; 
        st2.executeUpdate(query); 
       } 
       if(obj == btnDelete) 
       { 
        int no =Integer.parseInt(txtNo.getText()); 
        String query="delete from Student where sNo = "+no+" " ; 
        st2.executeUpdate(query); 
       } 
       if(obj == btnExit) 
       { 
        System.exit(0); 
       } 
      } 
      catch(Exception ex) 
      { 
       System.out.println(ex); 
      } 
     } 
    } 

Jeśli piszę st1=cn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE,ResultSet.HOLD_CURSORS_OVER_COMMIT); otrzymuję wyjątek java.lang.UnsupportedOperationException.

Muszę użyć ResultSet.HOLD_CURSORS_OVER_COMMIT ze względu na to, że chcę zachować zdolność po dodaniu nowego rekordu.

Answer 1

Ogólnie, java.lang.UnsupportedOperationException oznacza, że ​​implementator nie chce wdrożyć metody. W tym przypadku ludzie Odbc zdecydowali się nie wdrażać trzyargumentowego przeciążenia metody createConnection, prawdopodobnie dlatego, że nie obsługują one zdolności utrzymywania.

Pamiętam, że kiedyś słyszałem (gdzie?), Że ludzie z rodziny Java nie uważają sterownika ODbc za jakość produkcji. Więc jeśli uderzasz w bazę danych mysql lub coś takiego, lepiej byłoby użyć sterowników specyficznych dla danego dostawcy.

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Aha, a przy okazji, jeśli to nie jest kod wyrzucania, NIGDY nie mieszaj GUI i SQL w tej samej klasie.