从文本字段获取信息，以便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:"name"one_answers"姓氏"。我需要的信息，有人在那里键入的文本区域在另一个类。到目前为止，我设法写(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();
        }
    });
}
}

另一个类现在:

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();
        }
    });
}

}

但是我在橱窗里看到的是:"你今天怎么样，null null?"有新发现吗?由于

Answer 1

您从未向我们展示您已经证明在文本输入到字段之后和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。

我给这个类JTextFields公共getter方法，而不是公共变量，在getter方法中，我提取当前对应的JTextField中的文本。例如:

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，下面是演示您的问题和解决方案的SSCCE:

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());
            }
         }
      }));
   }
}

Answer 2

据我所知，当按下"enter"键时，JTextFields只会触发动作。Java教程

如果你在文本域中输入文本并在开始另一个类/框架之前按"enter"键，它是否工作?

那么更好的解决方案当然是getter，就像已经提到的气垫船:

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

Answer 3

最好使用getter方法:

(Person类):

// public String name;
// public String surname;
// ...
public Person()
{
    // ...
    nameField = new JTextField();
    nameField.addActionListener(this);
    surnameField = new JTextField();
    surnameField.addActionListener(this);
    // and in public void actionPerformed(ActionEvent e) {
    // name = nameField.getText();
    // surname = surnameField.getText();
    // ...
}
private String getName(){return nameField.getText();}
private String getSurname(){return surnameField.getText();}
// ...

另一个类:

Person person = new Person();
String name = person.getName();
String surname = person.getSurname();
String q = "How are you today, "+name+" "+surname+"?";
JTextArea textArea = new JTextArea(q);

Answer 4

一种方法是为这些值创建访问器。所以你应该输入:

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

和

String getName()
{
     surnameField.getText();
} 

在其他类中你只需调用这些方法返回值。

你应该让你的实例变量为私有的，永远不要让它们成为公共的(除非你有很好的理由)。阅读