Java JDBC delete database

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

class DeleteDatabase{
    public static void main(String[] args){
      JFrame f=new JFrame();
      f.setLayout(null);
      JLabel lab=new JLabel("Select");
      final JComboBox combo=new JComboBox();
      JButton b=new JButton("Delete");
      combo.addItem("<-Select->");
      try {
            Class.forName("com.mysql.jdbc.Driver");
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/", "root", "root");
            final Statement st = con.createStatement();
            ResultSet rs = st.executeQuery("show databases");

            while (rs.next()) {
                combo.addItem(rs.getString("Database"));
            }
            b.addActionListener(new ActionListener(){
                public void actionPerformed(ActionEvent e){
                String str= combo.getSelectedItem().toString();
                try{
                String sql = "DROP DATABASE "+str+"";
                st.executeUpdate(sql);
                }
                catch(Exception ex){}
                JOptionPane.showMessageDialog(null,"Database deleted successfully");
                }
            });
             }
            catch(Exception e){}
            lab.setBounds(10,10,100,20);
            combo.setBounds(120,10,150,20);
            b.setBounds(120,40,100,20);
            f.add(lab);
            f.add(combo);
            f.add(b);
            f.setVisible(true);
            f.setSize(350,150);
        }
}