Question

所以这是我的代码。我在面板中创建了一个菜单栏，其中有三个菜单，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。单击相应的菜单项后，表单应显示在包含菜单栏的原始面板下方的另一个面板中。此表单应根据单击的Menuitem输入Employee，Merchandise或Customer。填写表单后，有一个提交按钮（在表单中）单击，应该创建一个新的窗口/弹出/对话框，它应该打印在表单中输入的详细信息。我的问题从第一行开始。 216到行号。 225.当我点击Customer菜单项的“submit3”按钮时，会出现弹出窗口但不显示包含“txt1”内容的字符串的内容。如何将我的组件的值传递给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);
}


}

Answer 1

您的代码有几个问题，但问题的根源是您创建String时的时间。您在创建显示的JPanel时创建它，而不是在按下提交按钮时创建它。一个快速的临时解决方案是让您的JTextField成为最终，然后从提交JButton的ActionListener的里面中提取文本。

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 M odel- V iew- C ontrol结构，以从GUI中分离出程序逻辑。

使用有意义的变量名称，以便我的代码成为自我评论。例如，我将jTextField命名为firstNameField或类似名称，而不是txt1。

对我的每个JButtons使用AbstractActions而不是一个巨大的ActionListener供所有人共享。

Answer 2

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将JTextField txt1置于actionPerformedMethod内您可以像这样移动声明：

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

现在您可以像这样推荐txt1

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

如何将参数传递给/ override ActionPerformed（）

2 个答案: