如何动态地 get/set JRadionButtonMenuItem？

Question

此示例的单选按钮位于子菜单上，如此处所示。

我想做的是，只要按下“更改单选按钮”按钮，它就会更改菜单上 select 编辑的按钮。这意味着它必须首先检索当前设置的那个，然后 select 另一个。

对于这个简单的示例，可以将单选按钮设为实例变量以使事情变得简单，但是图像 JMenu 和相关联的子菜单和单选按钮的生成是 class程序。直接访问不是那么直接。

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;

import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JRadioButtonMenuItem;

public class RadioButtonsOnMenu 
{
    public static void main(final String args[]) 
    {
        JFrame frame = new JFrame("MenuSample Example");
        JButton jButton = new JButton("Change Radio Button");
        jButton.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent arg0) {
                System.out.println("Changing Radion Button");
                //How to change the JButton on the menu?
                //frame.getMenuBar().......
            }
        });

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel jPanel = new JPanel();
        jPanel.add(jButton);
        
        frame.add(jPanel);
        frame.setJMenuBar(buildMenu());
        frame.setSize(350, 250);
        frame.setVisible(true);
    }
    
    public static JMenuBar buildMenu()
    {
        JMenuBar menuBar = new JMenuBar();
        JMenu fileMenu = new JMenu("File");
        fileMenu.setMnemonic(KeyEvent.VK_F);
        menuBar.add(fileMenu);

        JMenuItem newMenuItem = new JMenuItem("New", KeyEvent.VK_N);
        fileMenu.add(newMenuItem);

        JMenu findOptionsMenu = new JMenu("Options");
        findOptionsMenu.setMnemonic(KeyEvent.VK_O);
        fileMenu.add(findOptionsMenu);

        ButtonGroup directionGroup = new ButtonGroup();
        
        JRadioButtonMenuItem forwardMenuItem = new JRadioButtonMenuItem("Forward", true);
        forwardMenuItem.setMnemonic(KeyEvent.VK_F);
        findOptionsMenu.add(forwardMenuItem);
        directionGroup.add(forwardMenuItem);

        JRadioButtonMenuItem backwardMenuItem = new JRadioButtonMenuItem("Backward");
        backwardMenuItem.setMnemonic(KeyEvent.VK_B);
        findOptionsMenu.add(backwardMenuItem);
        directionGroup.add(backwardMenuItem);
        
        return menuBar;
    }
}

不清楚如何最好地访问 JButton 操作中的子菜单和关联的单选按钮设置。

        jButton.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent arg0) {
                System.out.println("Changing Radion Button");
                //How to change the JButton on the menu?
                //frame.getMenuBar().......
            }
        });

我可能会从框架中获取菜单栏并深入研究代码，如果菜单栏有许多项目、子项目甚至多个单选按钮组，代码会变得混乱。

是否有更直接的方法来找出菜单上的哪些单选按钮 selected 以及更直接的方法来更改它们的值？

Answer 1

您可以做的是将状态保存为布尔值。您可以向单选按钮添加侦听器，并在每次选择其中一个按钮时更改布尔值

boolean isForward = true;

所以当更改为向后时，您将值设置为 false。这样你就不需要每次都获取单选按钮的状态。在您的按钮动作监听器中，您可以执行以下操作：

jButton.addActionListener(new ActionListener(){
    public void actionPerformed(ActionEvent arg0) {
        System.out.println("Changing Radion Button");

            forwardRadioButton.setState(!isForward);
            backwardRadioButton.setState(isForward);
            iSForward = !isForward;
     }
});

Answer 2

“诀窍”是创建一个应用程序模型来保存菜单单选按钮的值。

这是我创建的 GUI。

我通过调用 SwingUtilities invokeLater 方法启动了 Swing 应用程序。此方法确保 Swing 组件在 Event Dispatch Thread.

上创建和执行

我创建了一个 JFrame 和一个 JButton JPanel。我分开创建了 JFrame 和 JPanel.

我创建了一个应用程序模型 class 来保存一个布尔值，该布尔值确定是选择前进还是后退。 JButton ActionListener 切换布尔值的状态。 updateRadioButtonMenu 方法更新单选按钮菜单项的选定状态。

这是完整的可运行代码。

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;

import javax.swing.BorderFactory;
import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JRadioButtonMenuItem;
import javax.swing.SwingUtilities;

public class RadioButtonsOnMenu implements Runnable {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new RadioButtonsOnMenu());
    }
    
    private ApplicationModel model;
    
    private JRadioButtonMenuItem backwardMenuItem;
    private JRadioButtonMenuItem forwardMenuItem;
    
    public RadioButtonsOnMenu() {
        this.model = new ApplicationModel();
    }

    @Override
    public void run() {
        JFrame frame = new JFrame("MenuSample Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setJMenuBar(createMenuBar());

        frame.add(createButtonPanel());
        
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }
    
    private JMenuBar createMenuBar() {
        JMenuBar menuBar = new JMenuBar();
        JMenu fileMenu = new JMenu("File");
        fileMenu.setMnemonic(KeyEvent.VK_F);
        menuBar.add(fileMenu);

        JMenuItem newMenuItem = new JMenuItem("New", KeyEvent.VK_N);
        fileMenu.add(newMenuItem);

        JMenu findOptionsMenu = new JMenu("Options");
        findOptionsMenu.setMnemonic(KeyEvent.VK_O);
        fileMenu.add(findOptionsMenu);

        ButtonGroup directionGroup = new ButtonGroup();

        forwardMenuItem = new JRadioButtonMenuItem("Forward", model.isForward());
        forwardMenuItem.setMnemonic(KeyEvent.VK_F);
        findOptionsMenu.add(forwardMenuItem);
        directionGroup.add(forwardMenuItem);

        backwardMenuItem = new JRadioButtonMenuItem("Backward", !model.isForward());
        backwardMenuItem.setMnemonic(KeyEvent.VK_B);
        findOptionsMenu.add(backwardMenuItem);
        directionGroup.add(backwardMenuItem);

        return menuBar;
    }
    
    private JPanel createButtonPanel() {
        JPanel panel = new JPanel();
        panel.setBorder(BorderFactory.createEmptyBorder(100, 100, 100, 100));
        
        JButton button = new JButton("Change Radio Button");
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent event) {
                model.setForward(!model.isForward());
                updateRadioButtonMenu();
            }
        });
        panel.add(button);
        
        return panel;
    }
    
    public void updateRadioButtonMenu() {
        forwardMenuItem.setSelected(model.isForward());
        backwardMenuItem.setSelected(!model.isForward());
    }
    
    public class ApplicationModel {
        
        private boolean isForward;
        
        public ApplicationModel() {
            this.isForward = true;
        }

        public boolean isForward() {
            return isForward;
        }

        public void setForward(boolean isForward) {
            this.isForward = isForward;
        }
        
    }

}

Answer 3

我会说你需要做这两件事：

由于您似乎有很多物品，所以最好将它们存放在其他地方

1 创建一个 class 来存储所有项目，然后只传递 class

public class myItemHolder{
    //declare all the items here instead of at the main
    JButton jButton = new JButton("Change Radio Button");
    ButtonGroup directionGroup = new ButtonGroup();
    JRadioButtonMenuItem forwardMenuItem = new JRadioButtonMenuItem("Forward", true);
    JRadioButtonMenuItem backwardMenuItem = new JRadioButtonMenuItem("Backward");
    
    myListener(myItemHolder items){
        directionGroup.add(forwardMenuItem);
    }
    public ButtonGroup getButtons() {
        return directionGroup;
    }
    public JButton getClick() {
        return jButton;
    }
}

2 创建您自己的动作侦听器 class 像这样

public class myListener implements ActionListener{
    myItemHolders items;
    myListener(myItemHolder items){
        this.items=items; 
    }
    @Override
    public void actionPerformed(ActionEvent e) {
        //get the radiobutton like so and do what you want with it
        items.getButtons()
    }
}

现在您只需要在主要部分执行此操作：

public class RadioButtonsOnMenu 
{
    public static void main(final String args[]) 
    {
        myItemHolder items = new myItemHolder();
        items.getClick.addActionListener(new myListener(items));
    }
}

在那里您可以轻松访问所有内容:)
这完全取决于你在哪里声明你的东西。
或者，如果您只想发送 ButtonGroup，您可以通过稍微更改结构来实现，这样 actionlistener 只请求 ButtonGroup 并给它 items.getButtons() 而不是 items.

Answer 4

这是使用枚举状态跟踪的另一种可行方法。我使用 Enum 和 Map 来跟踪应该激活的单选按钮。这让它可以根据需要在同一个 JMenu 中为关联的单选按钮项目缩放。

收音机菜单

package tools;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.HashMap;

import javax.swing.JMenu;
import javax.swing.JRadioButtonMenuItem;

public class RadioMenu<E extends Enum<E>> extends JMenu {
  private static final long serialVersionUID = 1L;
  
  private E currentState;
  private JRadioButtonMenuItem selectedRadioButton;
  
  private HashMap<E, JRadioButtonMenuItem> stateMap;
  
  public RadioMenu() {
    stateMap = new HashMap<E, JRadioButtonMenuItem>();
  }
  
  public RadioMenu(String name) {
    super(name);
    stateMap = new HashMap<E, JRadioButtonMenuItem>();
  }
  
  public void addRadioButton(E associatedState, JRadioButtonMenuItem radioButton) {
    //Set default to first added button
    if(stateMap.isEmpty()) {
      currentState = associatedState;
      radioButton.setSelected(true);
      selectedRadioButton = radioButton;
    }
    
    add(radioButton);
    stateMap.put(associatedState, radioButton);
    radioButton.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent e) {
        setState(associatedState);
      }
    });
  }
  
  public void generateButtonsFromEnum(Class<E> enumType) {
    for(E enumValue : enumType.getEnumConstants()) {
      addRadioButton(enumValue, new JRadioButtonMenuItem(enumValue.toString()));
    }
  }
  
  public E getState() {
    return currentState;
  }
  
  public void setState(E newState) {
    currentState = newState;
    selectedRadioButton.setSelected(false);
    
    selectedRadioButton = stateMap.get(newState);
    selectedRadioButton.setSelected(true);
  }
}

RadioMenuTest

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

import tools.RadioMenu;

public class RadioMenuTest implements Runnable {

  public enum RadioOptions {
    Forward, Backward, Left, Right
  }
  
  public static void main(String[] args) {
    SwingUtilities.invokeLater(new RadioMenuTest());
  }
  
  private RadioMenu<RadioOptions> optionsMenu;
  
  @Override
  public void run() {
    JFrame frame = new JFrame("RadioMenu Test");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    
    frame.setJMenuBar(createMenuBar());
    frame.getContentPane().add(createButtonPanel());
    
    frame.pack();
    frame.setLocationByPlatform(true);
    frame.setVisible(true);
  }

  private JMenuBar createMenuBar() {
    JMenuBar menuBar = new JMenuBar();
    JMenu fileMenu = new JMenu("File");
    menuBar.add(fileMenu);
    
    optionsMenu = new RadioMenu<RadioOptions>("Options");
    optionsMenu.generateButtonsFromEnum(RadioOptions.class);
    
    fileMenu.add(optionsMenu);
    
    return menuBar;
  }
  
  private JPanel createButtonPanel() {
    JPanel panel = new JPanel(new FlowLayout());
    
    JButton setBackwardButton = new JButton("Set To Backward");
    setBackwardButton.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent e) {
        optionsMenu.setState(RadioOptions.Backward);
      }
    });
    panel.add(setBackwardButton);
    
    JButton setRightButton = new JButton("Set To Right");
    setRightButton.addActionListener(new ActionListener() {
      @Override
      public void actionPerformed(ActionEvent e) {
        optionsMenu.setState(RadioOptions.Right);
      }
    });
    panel.add(setRightButton);
    
    return panel;
  }
}

如何动态地 get/set JRadionButtonMenuItem？

How to get/set JRadionButtonMenuItem dynamically?

java

swing

jradiobutton

jmenuitem