类似于JFrame.pack包()对于JPanel

我有一个JPanel,我想设置它的宽度,但是让高度由它的内容决定。包含的JPanel应该保持其大小。如果我在“内容”中放置多行文本,它当然会自动跨越更多的高度。如果所需的高度超过容器的可用高度,滚动条将是理想的(但这不太重要)。

这可能真的很简单,但我就是搞不懂。。。

import java.awt.BorderLayout;
import java.awt.Color;
import javax.swing.BorderFactory;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class JPanelContentSizedDemo {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(JPanelContentSizedDemo::new);
    }

    JPanelContentSizedDemo() {
        JFrame frame = new JFrame("Demo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(400, 300);
        frame.setResizable(false);
        frame.setLayout(null);

        // the containing panel
        JPanel panelContainer = new JPanel();
        panelContainer.setBorder(BorderFactory.createEmptyBorder(10, 10, 10, 10));
        panelContainer.setBounds(50, 50, 300, 200);
        panelContainer.setBackground(Color.RED);
        frame.add(panelContainer);
        
        // what to do...
        //panelContainer.setLayout(new BoxLayout(panelContainer, BoxLayout.Y_AXIS));
        panelContainer.setLayout(new BorderLayout());

        // the panel that I want to size to its content
        JPanel dialog = new JPanel(new BorderLayout());
        dialog.setBackground(Color.GREEN);
        dialog.setBorder(BorderFactory.createLineBorder(Color.BLACK));
        dialog.add(new JLabel("This is some content!"));
        panelContainer.add(dialog);
        
        frame.setVisible(true);
    }
}