通过不使用JPanel和JFrame，如果函数返回true，我还能打开新窗口吗？ 否则如何向其中添加JPanel或JFrame？

Question

So this is the constructor for a window

setLayout(new FlowLayout());
    username = new JTextField("Username");
    password = new JTextField("Password");
    loginlogo = new JLabel(logo6);
    login = new JButton("LOGIN");
    login.setActionCommand("connect");
    login.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent event) {
            //on clicking connect: the real meat of the log in page
            usernamestring = username.getText();
            passwordstring = password.getText();
            logindataurl = ("URL/aphpscript.php?u=" + username + "&p=" + password);
            try {
                userdatabase = new URL(logindataurl);
                in = new BufferedReader(new InputStreamReader(userdatabase.openStream()));
                checkusername = in.read();
                in.close();
            } catch (MalformedURLException e) {
                new error_messagebox("Malformed URL Exception", e.toString());
            } catch (IOException e) {
                new error_messagebox("Input/Output Exception reading url ", e.toString());
            }


        }
    });

    add(loginlogo, BorderLayout.NORTH);
    add(username,BorderLayout.EAST);
    add(password,BorderLayout.WEST);
    add(login,BorderLayout.SOUTH);

and heres how i call it in main

login.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    login.setSize(500,350);
    login.setIconImage(logo3);
    login.setVisible(true);

but in main if a statement is returned true i would like to go onto the next box, its at this stage I realized there was such a thing as JPanel and JFrame,

I dont realy understand what they are for if theres two types of containers but I have heard this was the way to use an action listener to go to another window if some function allows it, I realy dont understand the existence of panel and frame at all anymore,

is there an easy work around? or do i have to make big changes to the code??

Answer 1

A JFrame is a Swing component that holds your Java application. Think of it as the window that appears on your computer. A JFrame can have a menu bar (JMenuBar).

A JPanel is a Swing component that holds other Swing components, like labels (JLabel), text entry fields (JTextArea) and buttons (JButton).

A JFrame should have one main JPanel. Depending on how you want to arrange your Swing components, you may need additional JPanels.

Your code appears to be putting together a login. You would usually use a JDialog to perform a login.

The flow goes like this.

• Start your Swing GUI by invoking SwingUtilities.invokeLater(Runnable)

• Define your JFrame, JPanel(s), and all of your Swing components.

• Show the JFrame

• Show the login JDialog

• If the credentials are valid, allow access to the GUI.

The Oracle Swing Tutorial will help you make sense of Swing.