Java Swing JButton对齐-BoxLayout

下面是一个小示例，其中两个单选按钮偏离左列太远

但是，如果我通过注释此代码删除上面的“A”按钮：

然后，2个单选按钮按预期显示，不偏移：

如何使单选按钮像第二种情况一样正确对齐，但有按钮存在？代码如下：

Main.java：

package layoutdemo;

import java.awt.Color;
import java.awt.Frame;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.WindowConstants;

public class Main extends JFrame {  
    public Main() {
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setExtendedState(Frame.MAXIMIZED_BOTH);
        getContentPane().setLayout(new BoxLayout(this.getContentPane(), BoxLayout.X_AXIS));
        getContentPane().setBackground(Color.black);
        add(new LeftPanel());
        pack();
        setVisible(true);
    }

    public static void main(String args[]) {
        new Main();
    }
}

LeftPanel.java：

package layoutdemo;

import java.awt.Component;
import java.awt.Dimension;

import javax.swing.BoxLayout;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

public class LeftPanel extends JPanel {
    public LeftPanel() {
        this.setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
        //add(new ButtonPanel());
        add(new JRadioButton("RadioBut2"));
        add(new JRadioButton("RadioBut1"));
    }

    @Override
    public Dimension getPreferredSize() {
        Component p = getParent();
        while(p.getParent() != null) {
            p = p.getParent();
        }
        Dimension dimension = p.getSize();
        return new Dimension(100, (int) (dimension.getHeight()));
    }
    
    @Override 
    public Dimension getMaximumSize() {
        return getPreferredSize();
    }
}

package layoutdemo;

import java.awt.Component;
import java.awt.Dimension;

import javax.swing.JPanel;
import javax.swing.JToggleButton;

public class ButtonPanel extends JPanel {
    public ButtonPanel() {
        add(new JToggleButton("A"));
    }
    
    @Override
    public Dimension getPreferredSize() {
        Component p = getParent();
        while(p.getParent() != null) {
            p = p.getParent();
        }
        Dimension dimension = p.getSize();
        return new Dimension(dimension.width, 50);
    }
    
    @Override 
    public Dimension getMaximumSize() {
        return getPreferredSize();
    }
}

ButtonPanel.java：

package layoutdemo;

import java.awt.Component;
import java.awt.Dimension;

import javax.swing.BoxLayout;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

public class LeftPanel extends JPanel {
    public LeftPanel() {
        this.setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
        //add(new ButtonPanel());
        add(new JRadioButton("RadioBut2"));
        add(new JRadioButton("RadioBut1"));
    }

    @Override
    public Dimension getPreferredSize() {
        Component p = getParent();
        while(p.getParent() != null) {
            p = p.getParent();
        }
        Dimension dimension = p.getSize();
        return new Dimension(100, (int) (dimension.getHeight()));
    }
    
    @Override 
    public Dimension getMaximumSize() {
        return getPreferredSize();
    }
}

package layoutdemo;

import java.awt.Component;
import java.awt.Dimension;

import javax.swing.JPanel;
import javax.swing.JToggleButton;

public class ButtonPanel extends JPanel {
    public ButtonPanel() {
        add(new JToggleButton("A"));
    }
    
    @Override
    public Dimension getPreferredSize() {
        Component p = getParent();
        while(p.getParent() != null) {
            p = p.getParent();
        }
        Dimension dimension = p.getSize();
        return new Dimension(dimension.width, 50);
    }
    
    @Override 
    public Dimension getMaximumSize() {
        return getPreferredSize();
    }
}

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这可能与这些项目的“alignmentX”属性有关。正在尝试将所有这些项设置为相同的alignmentX值

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（1+）有关更多信息，请查看上的Swing教程部分。谢谢！我设置buttonpanel.setAlignmentX（0）；buttonpanel是我上面例子中的“A”按钮，奇怪的是，它固定了下面单选按钮的对齐方式。但是，如果我将“A”按钮下面的单选按钮分别设置为setAlignmentX（0），则它没有任何效果，仍然与上面相同。有点违反直觉。