java - 从文本字段获取信息以在其他类的文本区域中使用它

Question

我有一个类，其中有两个文本字段:“姓名”和“姓氏”。我需要有人在另一个类(class)的文本区域中输入的信息。到目前为止，我设法编写了(Person 类):

public class Person extends JPanel implements ActionListener {

TextField nameField;
JTextField surnameField;
public String name;
public String surname;
final static int BIG_BORDER = 75;
final static int SMALL_BORDER = 10;
final static int ELEMENTsLENGHT = 320;
final static int VERTICAL_SPACE = 10;
final static int VERTICAL_SPACE_PLUS = 25;
final static int HORIZONTAL_SPACE = 75;
final static int SPACEforELEMENT_LABEL = 50;
final static int SPACEforELEMENT_TEXT = 40;
final static int H_SPACEforBUTTON = 64;
final static int V_SPACEforBUTTON = 26; 

public Person() {
    init();
}

public void init() {

    JLabel nameLabel = new JLabel("Please enter your name:");
    JLabel surnameLabel = new JLabel("Please enter your surname:");

    nameField = new JTextField();
    nameField.addActionListener(this);
    surnameField = new JTextField();
    surnameField.addActionListener(this);

    nextButton = new JButton("NEXT");
    nextButton.setActionCommand(next);
    nextButton.addActionListener(this);

    JPanel panelButton = new JPanel();
    panelButton.add(nextButton);        

    double size[][] = {
            { BIG_BORDER, ELEMENTsLENGHT, HORIZONTAL_SPACE,
                    H_SPACEforBUTTON, SMALL_BORDER }, // Columns
            { BIG_BORDER, SPACEforELEMENT_LABEL, VERTICAL_SPACE,
                    SPACEforELEMENT_TEXT, VERTICAL_SPACE_PLUS,
                    SPACEforELEMENT_LABEL, VERTICAL_SPACE,
                    SPACEforELEMENT_TEXT, VERTICAL_SPACE_PLUS,
                    SPACEforELEMENT_LABEL, VERTICAL_SPACE,
                    V_SPACEforBUTTON, SMALL_BORDER } }; // Rows

    setLayout(new TableLayout(size));

    add(nameLabel, "1,1,1,1");
    add(nameField, "1,3,1,1");
    add(surnameLabel, "1,5,1,1");
    add(surnameField, "1,7,1,1");
    add(nextButton, "3,11,1,1");
}   

public static void createAndShowGUI() {
    JFrame frame = new JFrame("Identification");
    frame.getContentPane().add(new Person());
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(550, 450);
    frame.setResizable(false);
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
}

@Override
public void actionPerformed(ActionEvent e) {

    name = nameField.getText();
    surname = surnameField.getText();

    if (e.getActionCommand().equalsIgnoreCase(next)) {
        Person.showNextWindow();
    } 
}

public static void showNextWindow() {
    //cardLayout.next(this);
    System.out.println("go to the next window");
}

public static void main(String[] args) {
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            createAndShowGUI();
        }
    });
}
}

现在另一个类:

public class Greeting extends JPanel implements ActionListener {

Person person = new Person();   

String name = person.name;
String surname = person.surname;

public Greeting() {
    super(new BorderLayout());
    init();
}

public void init() {

    nextButton = new JButton("NEXT");
    nextButton.setActionCommand(next);      
    nextButton.addActionListener(this);     
    //nextButton.setMnemonic('rightArrow');     

    String q = "How are you today, "+name+" "+surname+"?";          

    JTextArea textArea = new JTextArea(q); 
    textArea.setLineWrap(true);
    textArea.setWrapStyleWord(true);
    textArea.setEditable(false);
    add(textArea, BorderLayout.NORTH);      

    JPanel btnPanel = new JPanel();     
    btnPanel.setLayout(new BoxLayout(btnPanel, BoxLayout.LINE_AXIS));
    btnPanel.setBorder(BorderFactory.createEmptyBorder(0, 10, 10, 10));
    btnPanel.add(Box.createHorizontalGlue());                       
    btnPanel.add(nextButton);
        btnPanel.setAlignmentX(RIGHT_ALIGNMENT);
    add(btnPanel, BorderLayout.SOUTH);      

} // end init

public static void showNextWindow() {
    //cardLayout.next(this);
    System.out.println("go to the next window");
}

public void actionPerformed(ActionEvent e) {

}

public static void createAndShowGUI() {

    JFrame frame = new JFrame("How are you");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().add(new Greeting());     
    frame.setSize(550, 450);
    frame.setResizable(false);
    //frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
}

public static void main(String[] args) {
    // Schedule a job for the event-dispatching thread:
    // creating and showing this application's GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            createAndShowGUI();
        }
    });
}

}

但是我在窗口中看到的是:“你今天好吗，null null？”有新的眼光来发现问题所在吗？谢谢

Answer 1

您从未向我们证明您已证明在将文本输入字段之后以及在其他地方使用字符串变量之前调用 ActionListener。无论如何，这是一个糟糕的设计。

我将为该类提供 JTextFields 公共(public) getter 方法，而不是公共(public)变量，并且在 getter 方法中，我将提取当前在相应 JTextField 中的文本。例如，类似:

private JTextField nameField = new JTextField();
private JTextField surnameField = new JTextField();

public String getName() {
  return nameField.getText();
}

public String getSurname() {
  return surnameField.getText();
}

//... etc...

例如，以下是一个 SSCCE，它演示了您的问题和解决方案:

import java.awt.event.ActionEvent;
import javax.swing.*;

public class InfoFromTextFields {
   private static void createAndShowUI() {
      JFrame frame = new JFrame("InfoFromTextFields");
      frame.getContentPane().add(new MainGui());
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      java.awt.EventQueue.invokeLater(new Runnable() {
         public void run() {
            createAndShowUI();
         }
      });
   }
}

class NamePanel extends JPanel {
   private JTextField nameField = new JTextField(10);
   private JTextField surnameField = new JTextField(10);

   public NamePanel() {
      add(new JLabel("Name:"));
      add(nameField);
      add(Box.createHorizontalStrut(15));
      add(new JLabel("Surname:"));
      add(surnameField);
   }

   public String getNameText() {
      return nameField.getText();
   }

   public String getSurnameText() {
      return surnameField.getText();
   }
}

class MainGui extends JPanel {
   private JTextField nameField = new JTextField(10);
   private JTextField surnameField = new JTextField(10);

   public MainGui() {
      nameField.setEditable(false);
      surnameField.setEditable(false);

      add(new JLabel("Name:"));
      add(nameField);
      add(Box.createHorizontalStrut(15));
      add(new JLabel("Surname:"));
      add(surnameField);

      add(Box.createHorizontalStrut(15));
      add(new JButton(new AbstractAction("Get Names") {
         @Override
         public void actionPerformed(ActionEvent arg0) {
            NamePanel namePanel = new NamePanel();
            int result = JOptionPane.showConfirmDialog(nameField, namePanel,
                     "Get Names", JOptionPane.OK_CANCEL_OPTION);
            if (result == JOptionPane.OK_OPTION) {
               nameField.setText(namePanel.getNameText());
               surnameField.setText(namePanel.getSurnameText());
            }
         }
      }));
   }
}