如何将参数传递给/重写ActionPerformed（）

Question

So this is my code below. I have created a Menu bar in a panel which has three Menus, the first one being "Add Information". In Add Information, I have added three Menu items: Employee, Merchandise and Customer. Upon clicking an appropriate Menu item, a form should appear in another panel below the original panel containing the Menubar. This form should take input of either Employee, Merchandise or Customer depending on which Menuitem was clicked. After filling the form, there is a submit button (within the form) clicking on which should create a new window/pop-up/dialog box which should print the details that were entered in the form. My problem starts from line no. 216 to line no. 225. When I click on the button "submit3" of the Customer menuitem, the pop-up appears but does not show the contents of the string that contains contents of "txt1". How do I pass the values of my components to actionPerformed so that it can print them in a new pop-up window?

import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
import javax.swing.border.TitledBorder;

public class Retail extends JFrame implements ActionListener 
{
/**
 * 
 */
private static final long serialVersionUID = 1L;
JMenuBar menuBar = new JMenuBar();
JMenu addmenu = new JMenu("Add Information");
JMenu delmenu = new JMenu("Delete Information");
JMenu savemenu = new JMenu("Save Information");
JMenuItem emp = new JMenuItem("Employee");
JMenuItem merc = new JMenuItem("Merchandise");
JMenuItem cust = new JMenuItem("Customer");
Container contentPane = getContentPane();
JPanel p2 = new JPanel();

public Retail()
{
    super();
    contentPane.setLayout(new BorderLayout());
    JPanel p1 = new JPanel();
    p1.setBorder(new TitledBorder("Select Menu"));
    p1.setPreferredSize(new Dimension(500, 100));
    contentPane.add(p1,BorderLayout.NORTH);

    p2.setBorder(new TitledBorder("Entry Screen"));
    p2.setPreferredSize(new Dimension(500,500));    
    contentPane.add(p2,BorderLayout.CENTER);
    p2.setLayout(new BorderLayout());

    p1.add(menuBar);
    menuBar.add(addmenu);
    menuBar.add(delmenu);
    menuBar.add(savemenu);
    addmenu.add(emp);
    addmenu.addSeparator();
    addmenu.add(merc);
    addmenu.addSeparator();
    addmenu.add(cust);
    addmenu.addSeparator();


    emp.addActionListener(this);
    merc.addActionListener(this);
    cust.addActionListener(this);

}
public void actionPerformed(ActionEvent e)
{
    JButton submit1 = new JButton("Submit Employee Information"); 
    JButton submit2 = new JButton("Submit Merchandise Information");
    JButton submit3 = new JButton("Submit Customer Information");
    if(e.getSource() == emp)
    {   
        p2.removeAll();
        p2.updateUI();
        String[] states={"MA","AZ","CA"};
        JLabel lb1 = new JLabel("First Name:");
        JTextField txt1 = new JTextField(12);
        JLabel lb2 = new JLabel("Last Name:");
        JTextField txt2 = new JTextField(12);
        JLabel lb3 = new JLabel("Address:");
        JTextField txt3 = new JTextField(12);
        JLabel lb4 = new JLabel("City:");
        JTextField txt4 = new JTextField(12);
        JLabel lb5 = new JLabel("State");
        JComboBox cb1 = new JComboBox(states);
        JLabel lb6 = new JLabel("ZipCode");
        JTextField txt5 = new JTextField(12);
        JPanel p3 = new JPanel();
        p3.setLayout(new GridLayout(8,1));
        JPanel p4 = new JPanel();
        p4.setLayout(new GridLayout(1,2));
        JLabel lb7= new JLabel("Gender:");
        JRadioButton rb1 = new JRadioButton("Male");
        JRadioButton rb2 = new JRadioButton("Female");
        ButtonGroup bgroup = new ButtonGroup();
        bgroup.add(rb1);
        bgroup.add(rb2);
        JLabel lb8 = new JLabel("Submit Information:");
        JPanel p5 = new JPanel();
        p5.setLayout(new GridLayout(8,1));
        p3.add(lb1);
        p3.add(lb2);
        p3.add(lb3);
        p3.add(lb4);
        p3.add(lb5);
        p3.add(lb6);
        p3.add(lb7);
        p3.add(lb8);

        p5.add(txt1);
        p5.add(txt2);
        p5.add(txt3);
        p5.add(txt4);
        p4.add(rb1);
        p4.add(rb2);
        p5.add(cb1);
        p5.add(txt5);
        p5.add(p4);
        p5.add(submit1);

        p2.add(p3,BorderLayout.WEST);
        p2.add(p5,BorderLayout.EAST);

        submit1.addActionListener(this);
    }

    if(e.getSource() == merc)
    {
        p2.removeAll();
        p2.updateUI();
        String[] states={"MA","AZ","CA"};
        JLabel lb1 = new JLabel("First Name:");
        JTextField txt1 = new JTextField(12);
        JLabel lb2 = new JLabel("Last Name:");
        JTextField txt2 = new JTextField(12);
        JLabel lb3 = new JLabel("Address:");
        JTextField txt3 = new JTextField(12);
        JLabel lb4 = new JLabel("City:");
        JTextField txt4 = new JTextField(12);
        JLabel lb5 = new JLabel("State");
        JComboBox cb1 = new JComboBox(states);
        JLabel lb6 = new JLabel("ZipCode");
        JTextField txt5 = new JTextField(12);
        JPanel p3 = new JPanel();
        p3.setLayout(new GridLayout(8,1));
        JPanel p4 = new JPanel();
        p4.setLayout(new GridLayout(1,2));
        JLabel lb7= new JLabel("Gender");
        JRadioButton rb1 = new JRadioButton("Male");
        JRadioButton rb2 = new JRadioButton("Female");
        JLabel lb8 = new JLabel("Submit Information:");

        JPanel p5 = new JPanel();
        p5.setLayout(new GridLayout(8,1));
        p3.add(lb1);
        p3.add(lb2);
        p3.add(lb3);
        p3.add(lb4);
        p3.add(lb5);
        p3.add(lb6);
        p3.add(lb7);
        p3.add(lb8);
        p5.add(txt1);
        p5.add(txt2);
        p5.add(txt3);
        p5.add(txt4);
        p4.add(rb1);
        p4.add(rb2);
        p5.add(cb1);
        p5.add(txt5);
        p5.add(p4);
        p5.add(submit2);

        p2.add(p3,BorderLayout.WEST);
        p2.add(p5,BorderLayout.EAST);

        submit2.addActionListener(this);

    }
    if(e.getSource() == cust)
    {
        p2.removeAll();
        p2.updateUI();
        String[] states={"MA","AZ","CA"};
        JLabel lb1 = new JLabel("First Name:");
        JTextField txt1 = new JTextField(12);
        JLabel lb2 = new JLabel("Last Name:");
        JTextField txt2 = new JTextField(12);
        JLabel lb3 = new JLabel("Address:");
        JTextField txt3 = new JTextField(12);
        JLabel lb4 = new JLabel("City:");
        JTextField txt4 = new JTextField(12);
        JLabel lb5 = new JLabel("State");
        JComboBox cb1 = new JComboBox(states);
        JLabel lb6 = new JLabel("ZipCode");
        JTextField txt5 = new JTextField(12);
        JPanel p3 = new JPanel();
        p3.setLayout(new GridLayout(8,1));
        JPanel p4 = new JPanel();
        p4.setLayout(new GridLayout(1,2));
        JLabel lb7= new JLabel("Gender");
        JRadioButton rb1 = new JRadioButton("Male");
        JRadioButton rb2 = new JRadioButton("Female");
        JLabel lb8 = new JLabel("Submit Information:");
        JPanel p5 = new JPanel();
        p5.setLayout(new GridLayout(8,1));
        p3.add(lb1);
        p3.add(lb2);
        p3.add(lb3);
        p3.add(lb4);
        p3.add(lb5);
        p3.add(lb6);
        p3.add(lb7);
        p3.add(lb8);

        p5.add(txt1);
        p5.add(txt2);
        p5.add(txt3);
        p5.add(txt4);
        p4.add(rb1);
        p4.add(rb2);
        p5.add(cb1);
        p5.add(txt5);
        p5.add(p4);
        p5.add(submit3);

        p2.add(p3,BorderLayout.WEST);
        p2.add(p5,BorderLayout.EAST);
        final String s;
        s = txt1.getText();
        submit3.addActionListener(new ActionListener() 
        {
            @Override
            public void actionPerformed(ActionEvent args0) 
            {
                JOptionPane.showMessageDialog(rootPane,s);
            }
        });
    }
}
public static void main(String[] args)
{

    Retail frame = new Retail();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setTitle("Retail Information");
    frame.pack();
    frame.setResizable(true);
    frame.setVisible(true);
}


}

Answer 1

Your code has several issues, but the source of your problem is the timing of when you create the String, s. You are creating it when you create the JPanel that you display, not when the submit button has been pressed. One quick stop-gap solution is to make your JTextFields final, and then extract the text from them inside of the submit JButton's ActionListener.

eg,

  if (e.getSource() == cust) {
     p2.removeAll();
     p2.updateUI();
     String[] states = { "MA", "AZ", "CA" };
     JLabel lb1 = new JLabel("First Name:");
     final JTextField txt1 = new JTextField("Foo", 12);

     // ....

     // final String s;
     // s = txt1.getText();
     submit3.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent args0) {
           String s = txt1.getText();
           JOptionPane.showMessageDialog(rootPane, s);
        }
     });
  }

Having said this, if this were my code, I'd re-design it using a better overall plan.

Suggestions include:

• Subdivide this large class into logical sub-classes.
• Use CardLayout to swap views.
• Add a little MVC or odel- iew- ontrol structure to separate out the program logic from the GUI.
• Use variable names that make sense so that my code became self-commenting. For instance, instead of txt1, I'd name my JTextField firstNameField or something similar.
• Use AbstractActions for each of my JButtons rather than one huge ActionListener for all to share.

Answer 2

Maybe you can make JTextField txt1 , an instance variable which means that you put it in class scope variable Instead of placing the JTextField txt1 inside the actionPerformedMethod You can move the declaration like this:

public class Retail extends JFrame implements ActionListener 
{
private JTextField txt1 = new JTextField(12);

Now you can refer the txt1 like this

submit3.addActionListener(new ActionListener() 
{
@Override
public void actionPerformed(ActionEvent args0) 
{
String text = Retail.this.txt1.getText();
JOptionPane.showMessageDialog(rootPane,s);
}
});