不显示JCombobox

本文介绍了不显示JCombobox的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我正在使用以下代码通过使用JCombobox从数据库中选择其用户名来显示特定用户的详细信息.组合框用于列出表中的用户名.但是，当我运行代码时，组合框不可见. (虽然没有错误).如果有人告诉代码出了什么问题，那将很有帮助.预先感谢.

I am using the following code to display the particular user's details by using JCombobox to select his username from the database. The combo box is to list the user names from the table.But the combo box is not visible when i run the code. (no error though).It would be helpful if someone tell whats wrong with code. Thanks in advance.

public class EmpSearchApp extends JFrame implements ActionListener {

    JLabel l, l1, l2, l3, l4, l5, l6, l7, l8;
    JButton b;
    JTextField tf1, tf2, tf3, tf4, tf5, tf6, tf7;
    JComboBox bx;
    String str;

    EmpSearchApp() {
        setVisible(true);
        setSize(700, 700);
        setLayout(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("USER DATA");

        l = new JLabel("Select Name:");
        b = new JButton("Submit");

        tf1 = new JTextField();
        tf2 = new JTextField();
        tf3 = new JTextField();
        tf4 = new JTextField();
        tf5 = new JTextField();
        tf6 = new JTextField();
        tf7 = new JTextField();

        l.setBounds(20, 20, 200, 20);
        b.setBounds(50, 50, 150, 30);

        add(l);
        add(b);

        tf1.setEditable(false);
        tf2.setEditable(false);
        tf3.setEditable(false);
        tf4.setEditable(false);
        tf5.setEditable(false);
        tf6.setEditable(false);
        tf7.setEditable(false);
        b.addActionListener(this);

        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            Connection con = DriverManager.getConnection("jdbc:oracle:thin:@192.168.1.45:1521:orcl", "gemsexam", "gems123");
            PreparedStatement ps = con.prepareStatement("select uname from logf");
            ResultSet rs = ps.executeQuery();
            Vector v = new Vector();
            while (rs.next()) {
                String s = rs.getString(1);

                v.add(s);
            }
            bx = new JComboBox(v);
            bx.setBounds(240, 20, 200, 20);
            add(bx);

        } catch (Exception ex) {
            System.out.println(ex);
        }

    }

    public void actionPerformed(ActionEvent e) {
        showData();
    }

    public void showData() {
        JFrame f1 = new JFrame();
        f1.setVisible(true);
        f1.setSize(500, 500);
        f1.setLayout(null);
        f1.setTitle("USER DATA");

        l5 = new JLabel("Displaying Data:");
        l5.setForeground(Color.red);
        l5.setFont(new Font("Serif", Font.BOLD, 20));
        l1 = new JLabel("Name:");
        l2 = new JLabel("Contact:");
        l3 = new JLabel("email:");
        l4 = new JLabel("qual:");
        l6 = new JLabel("Tech:");
        l7 = new JLabel("status");
        l8 = new JLabel("address");

        l5.setBounds(100, 50, 300, 30);
        l1.setBounds(20, 110, 200, 20);
        l2.setBounds(20, 140, 200, 20);
        l3.setBounds(20, 170, 200, 20);
        l4.setBounds(20, 200, 200, 20);
        l6.setBounds(20, 230, 200, 20);
        l7.setBounds(20, 260, 200, 20);
        l8.setBounds(20, 290, 200, 20);

        tf1.setBounds(240, 110, 200, 20);
        tf2.setBounds(240, 140, 200, 20);
        tf3.setBounds(240, 170, 200, 20);
        tf4.setBounds(240, 200, 200, 20);
        tf5.setBounds(240, 230, 200, 20);
        tf6.setBounds(240, 260, 200, 20);
        tf7.setBounds(240, 290, 200, 20);

        f1.add(l5);
        f1.add(l1);
        f1.add(tf1);
        f1.add(l2);
        f1.add(tf2);
        f1.add(l3);
        f1.add(tf3);
        f1.add(l4);
        f1.add(tf4);
        f1.add(l6);
        f1.add(tf5);
        f1.add(l7);
        f1.add(tf6);
        f1.add(l8);
        f1.add(tf7);

        str = (String) bx.getSelectedItem();
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            Connection con = DriverManager.getConnection("jdbc:oracle:thin:@192.168.1.45:1521:orcl", "gemsexam", "gems123");
            PreparedStatement ps = con.prepareStatement("select * from logf where uname=?");
            ps.setString(1, str);
            ResultSet rs = ps.executeQuery();
            while (rs.next()) {

                tf1.setText(rs.getString(1));
                tf2.setText(rs.getString(2));
                tf3.setText(rs.getString(3));
                tf4.setText(rs.getString(4));
                tf5.setText(rs.getString(4));
                tf6.setText(rs.getString(4));
                tf7.setText(rs.getString(4));

            }
        } catch (Exception ex) {
            System.out.println(ex);
        }
    }

    public static void main(String arr[]) {
        new EmpSearchApp();
    }
}

setVisible

问题描述

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