Java 在选择面板中显示组合框的选择'；s文本字段

我试图在选择面板的文本字段中显示组合框的选择

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.text.ParseException;
import java.util.Date;
import javax.swing.AbstractButton;
  import javax.swing.BorderFactory;
 import javax.swing.JButton;
  import javax.swing.JComboBox;
  import javax.swing.JFrame;
  import javax.swing.JLabel;
  import javax.swing.JOptionPane;
  import javax.swing.JPanel;
  import javax.swing.JTextField;

 public class Department extends JFrame {

 private static final long serialVersionUID = 1L;

 public static final String Art = "Art";

 public static final String Biology = "Biology";

 public static final String Chemistry = "Chemistry";

 public static final String Computer_Science = "Computer_Science";
    public static final String Economics = "Economics";

     public static final String History = "History";

     public static final String Music = "Music";

    public static final String Philosophy = "Philosophy";
    public static final String Physics = "Physics";

     public static final String Psycholgy = "Psychology";
       public static final String Psychology = "Psychology";

  //constructor
  public Department() {
   setSize(700, 150);

  setLocationRelativeTo(null);

  setVisible(true);// making the frame visible

  setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    setTitle("Banner Self Service For Brahmbhatt");

TermPanel（）

//使用网格布局 setLayout（新的GridLayout（1,1））； 添加（新JLabel（“选择一个部门”）

}))

getContentPane（）.add（面板）

}

---

}

您没有发布其他代码，因此我猜您忘了将侦听器添加到JComboBox。 如果此方法是在

ActionListener

对象中声明的，则可以执行此操作将此侦听器添加到

JComboBox

JComboBox cb = new JComboBox(); //sample declaration
cb.addActionListener(new ActionListener(){
    public void actionPerformed(ActionEvent e){
        //do your stuff here
    }
});

---

问题是？发布一个适当的例子来说明问题。（1-）你还没有说明问题是什么。2） 您发布的代码未格式化。了解如何正确使用论坛时，张贴代码是你希望人们阅读它。3） 这不是一个

MCVE

。您的问题是关于组合框和在面板中设置文本。因此，创建一个简单的

MCVE

。您只需要一个带有组合框和文本字段的框架。然后将ActionLIstener添加到组合框中，以在选择项目时更新文本字段。整个程序大约有20-25行代码，这使得调试变得很容易。一旦你理解了基本概念，你就可以修改你真正的代码。我编辑了代码，你现在能帮我吗。感谢您的帮助

JTextField textField=null为什么文本字段为空？另外，按照惯例，常量名称应该像ART一样大写，方法名称应该以小写字母开头，后面每个单词的第一个字母应该是大写，比如
private void TermPanel（）
应该是
private void TermPanel（）
。您的方法名称应该描述该方法的功能。因此，
initialize（）
将是
termPanel（）
的更好名称。希望我的评论能有所帮助。
 birthdayPanel.setBackground(new Color(250, 230, 230));
 String[] choices = { "","Art","Biology", 
"Chemistry","Computer_Science","Economics","English", "History", "Music", 
"Mathematics", "Philosophy", "Physics", "Psychology"};

//Creating a comboBox
 final JComboBox<String> cb = new JComboBox<String>(choices);
 cb.setVisible(true);

 birthdayPanel.add(cb);
 panel.add(birthdayPanel);

 getContentPane().add(panel);
 JTextField textField = null;


  //Panels for the selection term field
 zodiacSign.setEnabled(true);//so that no one can use it as input field 
 zodiacSign.setEditable(true);//so that no one can edit the zodiac sign

 selectionPanel.add(zodiacSign); // adding the zodiacsign textfield to panel
 zodiacSign.setMaximumSize(new Dimension(1000, 500));   //setting minimu 
 dimensions for the zodiac panel
 zodiacSign.setMinimumSize(new Dimension(500, 150));     //setting minimum 
  dimensions for the zodia

 selectionPanel.setBorder(BorderFactory.createTitledBorder("Your Selection 
    is"));
 selectionPanel.setBackground(new Color(250, 230, 230));
 panel.add(selectionPanel);

public void actionPerformed (ActionEvent event)
{
    JComboBox cb = (JComboBox) event.getSource();
    Object selected = cb.getSelectedItem();
    textField.setText((String) cb.getSelectedItem());
}

JComboBox cb = new JComboBox(); //sample declaration
cb.addActionListener(new ActionListener(){
    public void actionPerformed(ActionEvent e){
        //do your stuff here
    }
});