Question

我有这个GUI设置。 tl; dr是：它是一个gui，一个MenuItem调用myActionListener。

此课程中还有一个Object o。我希望myActionListener以及myActionListener2等可以访问这个对象。但我甚至无法调用任何Object方法。

          public class MenuDemo implements ActionListener,ItemListener{

//  My  Object

  Object o = new Object();
  o.addParam();// wont work 

public JMenuBar createMenuBar() {
        JMenuBar menuBar;
        JMenu menu, submenu;
        JMenuItem menuItem;

        menu = new JMenu("A Menu");
        menuBar.add(menu);
        menuItem = new JMenuItem("Title");
        menuItem.addActionListener(new myListener()); 
        menu.add(menuItem);

        return menuBar;
    }


public Container createContentPane() {
    //Create the content-pane-to-be.
    JPanel contentPane = new JPanel(new BorderLayout());
    contentPane.setOpaque(true);

    //Create a scrolled text area.
    output = new JTextArea(5, 30);
    output.setEditable(false);
    scrollPane = new JScrollPane(output);

    //Add the text area to the content pane.
    contentPane.add(scrollPane, BorderLayout.CENTER);

    return contentPane;
}

public Container createContentPane() {
    //Create the content-pane-to-be.
    JPanel contentPane = new JPanel(new BorderLayout());
    contentPane.setOpaque(true);

    //Create a scrolled text area.
    output = new JTextArea(5, 30);
    output.setEditable(false);
    scrollPane = new JScrollPane(output);

    //Add the text area to the content pane.
    contentPane.add(scrollPane, BorderLayout.CENTER);

    return contentPane;
}


 public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        Database db = new Database();
        final int test = 5;
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });

}

我一直试图弄清楚这一段时间，但似乎我无法找到任何帮助，或者我可能会以错误的方式去做它？

Answer 1

正如我在评论中所说，您可以将Object的引用传递给ActionListener的不同类型/子类型的对象：

主要课程：

import java.awt.EventQueue;
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JFrame;

public class Main extends JFrame
{
    private JButton btn;
    Object o;

    public Main()
    {
        setLayout(new FlowLayout());

        o = new String("Hello Beautiful!");

        btn = new JButton("Click!");

       //Passing the reference `o` to the constructor
        btn.addActionListener(new JButtonListener(o));

        add(btn);

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
        pack();
        setLocationRelativeTo(null);
    }

    public static void main(String[] args)
    {
        EventQueue.invokeLater(new Runnable() {
            public void run()
            {
                new Test1();
            }
        });
    }

}

实施ActionListener的类：

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JOptionPane;

public class JButtonListener implements ActionListener
{
    private Object _obj;

    public JButtonListener(Object obj)
    {
        _obj = obj;
    }

    @Override
    public void actionPerformed(ActionEvent e)
    {
        JOptionPane.showMessageDialog(null, _obj.toString());
    }
}

对来自不同ActionListeners的同一对象/列表执行操作

1 个答案: