BorderLayout无法正确显示

我想要一个JFrame，左边和右边有一个边框，颜色为黑色，宽度为withfOfJFrame / 10。

现在，我尝试它看起来像这样：

JFrame f = new JFrame(); f.setSize(800, 600); f.setLayout(new BorderLayout()); JPanel leftBorder = new JPanel(); JPanel rightBorder = new JPanel(); leftBorder.setBackground(Color.black); rightBorder.setBackground(Color.black); leftBorder.setSize(f.getWidth()/10, f.getHeight()); rightBorder.setSize(f.getWidth()/10, f.getHeight()); JPanel center = new JPanel(); center.setBackground(Color.red); f.add(leftBorder, BorderLayout.WEST); f.add(center, BorderLayout.CENTER); f.add(rightBorder, BorderLayout.EAST); f.setVisible(true); 

这会在左侧和右侧添加黑色边框，但该边框具有固定大小，并且在调整窗口大小时不会重新计算。 大小甚至不是800的1/10（JFrame的起始宽度）。

我究竟做错了什么？ 或者甚至有更好的方法来做到这一点？

Answer 1

您可以使用GridBagLayout和适当的权重来获得所需的结果：

 public class Snippet { public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { JFrame f = new JFrame(); f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); JPanel leftBorder = new JPanel(); JPanel rightBorder = new JPanel(); leftBorder.setBackground(Color.black); rightBorder.setBackground(Color.black); JPanel center = new JPanel(); center.setBackground(Color.red); f.setLayout(new GridBagLayout()); GridBagConstraints gbc = new GridBagConstraints(); gbc.fill = GridBagConstraints.BOTH; gbc.weighty = 1.0; gbc.gridy = 0; gbc.gridwidth = 1; gbc.gridheight = 1; gbc.gridx = 0; gbc.weightx = 0.1; f.add(leftBorder, gbc); gbc.gridx = 1; gbc.weightx = 0.8; f.add(center, gbc); gbc.gridx = 2; gbc.weightx = 0.1; f.add(rightBorder, gbc); f.pack(); f.setVisible(true); } }); } } 

Answer 2

ComponentListener适用于此。

附录： Flank面板需要显式revalidate()以响应任何大小更改。

 import java.awt.BorderLayout; import java.awt.Color; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.event.ComponentAdapter; import java.awt.event.ComponentEvent; import javax.swing.JFrame; import javax.swing.JPanel; /** @see http://stackoverflow.com/a/14588506/230513 */ public class Test { private static final int W = 320; private static final Center center = new Center(); private static class Center extends JPanel { public Center() { setBackground(Color.red); } @Override public Dimension getPreferredSize() { return new Dimension(W, 3 * W / 4); } }; private static class Flank extends JPanel { private Dimension d = new Dimension(W / 10, 0); public Flank() { setBackground(Color.black); Test.center.addComponentListener(new ComponentAdapter() { @Override public void componentResized(ComponentEvent e) { d = new Dimension(e.getComponent().getWidth() / 10, 0); revalidate(); } }); } @Override public Dimension getPreferredSize() { return d; } } private void display() { JFrame f = new JFrame("Test"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.add(new Flank(), BorderLayout.WEST); f.add(center, BorderLayout.CENTER); f.add(new Flank(), BorderLayout.EAST); f.pack(); f.setLocationRelativeTo(null); f.setVisible(true); } public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { new Test().display(); } }); } }