我无法从JDialog更新Jcombobox（通过模型）(I can't update Jcombobox (via model) from a JDialog)

 我有一个简单的用户界面，其中我的按钮调用我的方法updateModelCmb（），此方法只是增加计数器的值并更新模型。 该按钮似乎正确地为模型添加了适当的值。 但是当我在我的第二个UI类中做同样的事时，模型没有得到更新...我做错了什么？ 这里是我的代码： 
 
package testing;

import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JComboBox;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class OneUI extends JFrame {

private JPanel contentPane;
private JComboBox comboBox ;
private DefaultComboBoxModel modeltest;
private Integer count=0;
private JButton btnOpenSecondUi;
/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                OneUI frame = new OneUI();
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the frame.
 */
public OneUI() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 450, 300);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(null);

    JButton btnAddOne = new JButton("Add 1 element");
    btnAddOne.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            updateModelCmb();
        }
    });
    btnAddOne.setBounds(187, 46, 129, 23);
    contentPane.add(btnAddOne);
    modeltest= new DefaultComboBoxModel() ;
    comboBox= new JComboBox();
    comboBox.setBounds(48, 47, 129, 20);
    comboBox.setModel(modeltest);
    contentPane.add(comboBox);

    btnOpenSecondUi = new JButton("Open second UI");
    btnOpenSecondUi.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            new SecondUI();
        }
    });
    btnOpenSecondUi.setBounds(155, 163, 161, 23);
    contentPane.add(btnOpenSecondUi);
}

public void updateModelCmb(){
    count++;
    modeltest.addElement(count);
    comboBox.setModel(modeltest);

}

}
 
 这是第二类，似乎没有工作。 
 
package testing;

import java.awt.BorderLayout;

public class SecondUI extends JDialog {

private final JPanel contentPanel = new JPanel();

/**
 * Create the dialog.
 */
public SecondUI() {
    setVisible(true);
    setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
    setBounds(100, 100, 327, 142);
    getContentPane().setLayout(new BorderLayout());
    contentPanel.setLayout(new FlowLayout());
    contentPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
    final OneUI obj = new OneUI();
    getContentPane().add(contentPanel, BorderLayout.CENTER);
    {
        JButton btnAddOneElement = new JButton("Add 1 element");
        btnAddOneElement.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                obj.updateModelCmb();
            }
        });
        contentPanel.add(btnAddOneElement);
    }
}

}
 
 请帮忙 ：（ 

I have a simple UI in which my button that calls my method updateModelCmb(), this method just increases the value of a counter and updates the model. The button seems to add the proper values to the model just fine. But when I do the same in my secondUI class, the model does not gets updated... am I doing something wrong? here is my code:
 
package testing;

import java.awt.BorderLayout;
import java.awt.EventQueue;
import javax.swing.DefaultComboBoxModel;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JComboBox;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class OneUI extends JFrame {

private JPanel contentPane;
private JComboBox comboBox ;
private DefaultComboBoxModel modeltest;
private Integer count=0;
private JButton btnOpenSecondUi;
/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                OneUI frame = new OneUI();
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the frame.
 */
public OneUI() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 450, 300);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(null);

    JButton btnAddOne = new JButton("Add 1 element");
    btnAddOne.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            updateModelCmb();
        }
    });
    btnAddOne.setBounds(187, 46, 129, 23);
    contentPane.add(btnAddOne);
    modeltest= new DefaultComboBoxModel() ;
    comboBox= new JComboBox();
    comboBox.setBounds(48, 47, 129, 20);
    comboBox.setModel(modeltest);
    contentPane.add(comboBox);

    btnOpenSecondUi = new JButton("Open second UI");
    btnOpenSecondUi.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            new SecondUI();
        }
    });
    btnOpenSecondUi.setBounds(155, 163, 161, 23);
    contentPane.add(btnOpenSecondUi);
}

public void updateModelCmb(){
    count++;
    modeltest.addElement(count);
    comboBox.setModel(modeltest);

}

}
 
This is the second class which does not seem to work.
 
package testing;

import java.awt.BorderLayout;

public class SecondUI extends JDialog {

private final JPanel contentPanel = new JPanel();

/**
 * Create the dialog.
 */
public SecondUI() {
    setVisible(true);
    setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
    setBounds(100, 100, 327, 142);
    getContentPane().setLayout(new BorderLayout());
    contentPanel.setLayout(new FlowLayout());
    contentPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
    final OneUI obj = new OneUI();
    getContentPane().add(contentPanel, BorderLayout.CENTER);
    {
        JButton btnAddOneElement = new JButton("Add 1 element");
        btnAddOneElement.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                obj.updateModelCmb();
            }
        });
        contentPanel.add(btnAddOneElement);
    }
}

}
 
Please help :(

原文：https://stackoverflow.com/questions/31708263