java - BoxLayout 拒绝接受 JButton 的首选大小

Question

我一直在做一个模拟赌博游戏的小项目。不幸的是，我在使用 BoxLayout 时遇到了一些奇怪的问题。据我所知，LayoutManager 通常遵循任何组件的首选大小。但是，在下面的代码中，BoxLayout 没有。

到目前为止，这是我的代码:

import java.awt.*;
import javax.swing.*;



public class Main 
{
    public static void main(String[] args)
    {
      JFrame.setDefaultLookAndFeelDecorated(true);
      JFrame frame = new JFrame("Suit-Up");
      frame.setContentPane(makeGUI());
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setSize(900,450);
      frame.setLocationRelativeTo(null);
      frame.setResizable(false);
      frame.setVisible(true);
    }

    public static JPanel makeGUI()
    {
      JPanel main = new JPanel();
      main.setMinimumSize(new Dimension(900,450));
      main.setBackground(Color.red);

      JPanel infoPanel = new JPanel();
      infoPanel.setLayout(new BoxLayout(infoPanel, BoxLayout.LINE_AXIS));
      infoPanel.setPreferredSize(new Dimension(900,60));
      infoPanel.setBackground(Color.green);
      main.add(infoPanel);

      JPanel infoText = new JPanel();
      infoText.setLayout(new BoxLayout(infoText, BoxLayout.PAGE_AXIS));
      infoPanel.add(infoText);

      JPanel moneyText = new JPanel();
      moneyText.setLayout(new BoxLayout(moneyText, BoxLayout.LINE_AXIS));
      infoText.add(moneyText);

      JPanel lastGameText = new JPanel();
      lastGameText.setLayout(new BoxLayout(lastGameText, BoxLayout.LINE_AXIS));
      infoText.add(lastGameText);

      JButton playAgain = new JButton("Play Again ($20)");
      playAgain.setPreferredSize(new Dimension(200,60));
      infoPanel.add(playAgain);

      JButton finish = new JButton("End Session");
      finish.setPreferredSize(new Dimension(200,60));
      infoPanel.add(finish);

      JPanel cardPanel = new JPanel();
      cardPanel.setLayout(new BoxLayout(cardPanel, BoxLayout.LINE_AXIS));
      main.add(cardPanel);

      return main;
    }
}

尽管为两个 JButton 指定了首选大小，但它们并没有改变它们的大小。我也尝试了 setMaximumSize() 和 setMinimumSize()，但都没有任何效果。

我是否忽略了一些明显的东西，或者这是 BoxLayout 的限制？

Answer 1

“据我所知，LayoutManager 通常遵循任何组件的首选尺寸” - 这实际上不是真的。首选/最小/最大大小只是布局管理器可以用来确定如何最好地布局内容的“提示”。如果他们愿意，布局管理器可以简单地忽略它们。

来自 JavaDocs

BoxLayout attempts to arrange components at their preferred widths (for horizontal layout) or heights (for vertical layout). For a horizontal layout, if not all the components are the same height, BoxLayout attempts to make all the components as high as the highest component. If that's not possible for a particular component, then BoxLayout aligns that component vertically, according to the component's Y alignment. By default, a component has a Y alignment of 0.5, which means that the vertical center of the component should have the same Y coordinate as the vertical centers of other components with 0.5 Y alignment.

Similarly, for a vertical layout, BoxLayout attempts to make all components in the column as wide as the widest component. If that fails, it aligns them horizontally according to their X alignments. For PAGE_AXIS layout, horizontal alignment is done based on the leading edge of the component. In other words, an X alignment value of 0.0 means the left edge of a component if the container's ComponentOrientation is left to right and it means the right edge of the component otherwise.