JButton的ActionListener

Question

在下面的代码中，当取消选择_uiChkTestAction和_uiChkTestItem JCheckBox时，单击bu1按钮使它们都被选中，但是单击bu2按钮不会将_uiChkTestItem JCheckBox从未被选中更改为选中。

那么，我的代码有问题吗？

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;

public class TestActionItemListener
{
public static void main(String[] _args)
{
    EventQueue.invokeLater(new Runnable(){

    public void run(){

    JFrame _fra = new JFrame("Testing");
    _fra.setSize(500, 500);
    _fra.setLayout(new FlowLayout());
    final JCheckBox _uiChkTestAction = new JCheckBox("ActionListener");
    _uiChkTestAction.addActionListener(new ActionListener()
    {
        public void actionPerformed(ActionEvent _ev)
        {
            System.out.println("State by ActionListener: " + _uiChkTestAction.isSelected());
        }
    });

    final JCheckBox _uiChkTestItem = new JCheckBox("ItemListener");
    _uiChkTestItem.addItemListener(new ItemListener()
    {
        public void itemStateChanged(ItemEvent e)
        {
            System.out.println("State by ItemListener: " + _uiChkTestAction.isSelected());
        }
    });
    JButton bu1 = new JButton("actionlistener bu");
    bu1.addActionListener(new ActionListener(){

        @Override
        public void actionPerformed(ActionEvent e) {
          _uiChkTestAction.setSelected(true);
        }
     });
    JButton bu2 = new JButton("itemlistener bu");
    bu1.addActionListener(new ActionListener(){

        @Override
        public void actionPerformed(ActionEvent e) {
        _uiChkTestItem.setSelected(true);
        }
     });
    _fra.add(_uiChkTestAction);
    _fra.add(_uiChkTestItem);
    _fra.add(bu1);
    _fra.add(bu2);
    _uiChkTestAction.setSelected(true);
    _uiChkTestItem.setSelected(true);

    _fra.setVisible(true);
}}
);
}
};

Answer 1

您将两个听众添加到同一按钮bu1 iso，将一个添加到bu1，将一个添加到bu2

Answer 2

您要向bu1添加一次监听器两次。将第二个添加到bu2。