java - 如何将参数传递给/覆盖 ActionPerformed()

Question

所以这是我下面的代码。我在具有三个菜单的面板中创建了一个菜单栏，第一个是“添加信息”。在添加信息中，我添加了三个菜单项：员工、商品和客户。单击适当的菜单项后，表单应出现在包含菜单栏的原始面板下方的另一个面板中。此表单应输入员工、商品或客户，具体取决于单击的菜单项。填写表格后，有一个提交按钮（在表格内）点击它应该创建一个新的窗口/弹出/对话框，它应该打印在表格中输入的详细信息。我的问题从第 1 行开始。216到线号。225. 当我点击 Customer menuitem 的按钮“submit3”时，弹出窗口出现但不显示包含“txt1”内容的字符串的内容。如何将组件的值传递给 actionPerformed 以便它可以在新的弹出窗口中打印它们？

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);
}


}

score 2 · Accepted Answer

也许你可以制作JTextField txt1一个实例变量，这意味着你把它放在类范围变量中而不是放在JTextField txt1里面actionPerformedMethod 你可以像这样移动声明：

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

现在你可以参考txt1这样的

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

score 2 · Accepted Answer

您的代码有几个问题，但问题的根源是创建字符串 s 的时间。您是在创建显示的 JPanel 时创建它，而不是在按下提交按钮时创建它。一种快速的权宜之计是使您的 JTextFields 成为最终的，然后在提交 JButton 的 ActionListener 中从它们中提取文本。

例如，

  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);
        }
     });
  }

话虽如此，如果这是我的代码，我会使用更好的整体计划重新设计它。

建议包括：

将这个大类细分为逻辑子类。
使用 CardLayout 交换视图。
添加一点 MVC 或Model - View - Control结构以将程序逻辑从 GUI 中分离出来。
使用有意义的变量名，以便我的代码能够自我注释。例如，我将 JTextField 命名为 firstNameField 或类似名称，而不是 txt1。
对我的每个 JButton 使用 AbstractActions，而不是使用一个巨大的 ActionListener 供所有人共享。

java - 如何将参数传递给/覆盖 ActionPerformed()

2 回答 2

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