SQLITE Database is locked in java (IDE NetBeans)

问题

When I perform any action it works in database but suddenly it shows an error of Database is Locked!

Suppose this is the actionPerformed on one button:

private void jButton6ActionPerformed(java.awt.event.ActionEvent evt) {       
//Sahil_Computers.ConnecrDb(); is the database connecting method!                                  
    conn = Sahil_Computers.ConnecrDb();
    try{
      String sql = "insert into dailyExp (Sr,Description,Amount) values (?,?,?)";
      pst = conn.prepareStatement(sql);
      pst.setString(1, txt_srE.getText());
      pst.setString(2, txt_desE.getText());
      pst.setString(3, txt_rsE.getText());

      pst.execute();
      JOptionPane.showMessageDialog(null, "Saved!");
    }catch(Exception e){
        JOptionPane.showMessageDialog(null, e);
    }finally{
    try{
        rs.close();
        pst.close();
    }catch(Exception e){
        JOptionPane.showMessageDialog(null, e);
    }
}    
  update_table_exp();
}

and then again when I try to perform another action just like:

private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    conn = Sahil_Computers.ConnecrDb();
    String sql = "delete from dailySale where Sr=?";
    try{
        pst = conn.prepareStatement(sql);
        pst.setString(1, txt_sr1.getText());
        pst.execute();
        JOptionPane.showMessageDialog(null, "Deleted!");
    }catch(Exception e){
        JOptionPane.showMessageDialog(null, e);
    }finally{
    try{
        rs.close();
        pst.close();
    }catch(Exception e){
        JOptionPane.showMessageDialog(null, e);
    }
}    
  update_table_sale();
}

or action like this one:

private void jButton9ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    conn = Sahil_Computers.ConnecrDb();
    try{
        String sum = null, sub= null;
        String subto = null;
        int sum1, sub1, subto1;
        String sql = "select sum(Debit) from dailySale";
        pst=conn.prepareStatement(sql);
        rs=pst.executeQuery();
        if(rs.next()){
            sum = rs.getString("sum(Debit)");
            txt_tsale.setText(sum);
        }
        sql = "select sum(Amount) from dailyExp";
        pst=conn.prepareStatement(sql);
        rs=pst.executeQuery();
        if(rs.next()){
            sub = rs.getString("sum(Amount)");
            txt_texp.setText(sub);
        }
        sum1 = Integer.parseInt(sum);
        sub1 = Integer.parseInt(sub);
        subto1 = sum1 - sub1;
        subto = Integer.toString(subto1);
        txt_tsub.setText(subto);
    }catch(Exception e){
        JOptionPane.showMessageDialog(null, e);
    }finally{
    try{
        rs.close();
        pst.close();
    }catch(Exception e){
        JOptionPane.showMessageDialog(null, e);
    }}}

Then it shows database is locked!

回答1:

You must close any open connection before open a new one. You're opening a new connection conn = Sahil_Computers.ConnecrDb(); every time a button is pressed but you never close it. Add conn.close(); to your finally blocks.

Some off-topic concern: use PreparedStatement#executeUpdate() instead PreparedStatement#execute() when you need to execute an INSERT/UPDATE/DELETE statement.

来源：https://stackoverflow.com/questions/18367585/sqlite-database-is-locked-in-java-ide-netbeans