如何将GridBagLayout中的Swing组件垂直居顶显示？

你的问题出在GridBagConstraints的weighty属性设置上——所有组件的weighty都设为0，这意味着GridBagLayout会把所有组件挤在面板垂直方向的中间位置，因为没有分配任何额外垂直空间的权重。

要把组件顶到面板顶部，只需要给最后一行的组件设置weighty = 1.0，让额外的垂直空间被分配到这一行的下方，从而把上面的组件推到顶部。

修改后的代码如下：

setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
Border border = BorderFactory.createTitledBorder(null, "Saisie", TitledBorder.CENTER, TitledBorder.TOP, new Font("times new roman",Font.BOLD,14),Color.GRAY);
setBorder(border);

gbc.gridx = 0;
gbc.gridy = 0;
gbc.gridwidth = 1;
gbc.gridheight = 1;
gbc.weightx = 0.;
gbc.weighty = 0.;
gbc.fill = GridBagConstraints.NONE;
gbc.anchor = GridBagConstraints.LINE_END;
gbc.insets = new Insets(3, 3, 3, 3);
add(JLabel_ID, gbc);

gbc.gridx = 1;
gbc.gridy = 0;
gbc.gridwidth = 1;
gbc.gridheight = 1;
gbc.weightx = 0.;
gbc.weighty = 0.;
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.anchor = GridBagConstraints.CENTER;
gbc.insets = new Insets(3, 3, 3, 3);
add(JTextField_ID, gbc);

gbc.gridx = 0;
gbc.gridy = 1;
gbc.gridwidth = 1;
gbc.gridheight = 1;
gbc.weightx = 0.;
gbc.weighty = 0.;
gbc.fill = GridBagConstraints.NONE;
gbc.anchor = GridBagConstraints.LINE_END;
gbc.insets = new Insets(3, 3, 3, 3);
add(JLabel_Nom, gbc);

gbc.gridx = 1;
gbc.gridy = 1;
gbc.gridwidth = 1;
gbc.gridheight = 1;
gbc.weightx = 0.;
// 关键修改：给最后一行的组件设置weighty为1.0
gbc.weighty = 1.0;
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.anchor = GridBagConstraints.CENTER;
gbc.insets = new Insets(3, 3, 3, 3);
add(JTextField_Nom, gbc);

如果希望组件在垂直方向顶部对齐的同时，水平方向能填充可用空间，可以把对应组件的weightx设为1.0，配合fill = GridBagConstraints.HORIZONTAL使用，这是可选的优化设置。

内容的提问来源于stack exchange，提问作者nour tebbal