考慮以下圖：堆棧搖擺元素底部
我需要開發一個Swing GUI的外觀上來看是這樣的。我只是簡單地將它們命名爲jLabel's，但其中包含一些圖像和jLabel。可見的默認awt背景是JPanel，每個可見的紅色背景是一個serperate JPanel。現在我需要他們像上面顯示的那樣堆疊起來。我嘗試了一些佈局管理器，但仍然無法使用。
這裏重要的一點是紅色的div的數量不是恆定的。如果只有一個紅色的彩色格，那麼它必須顯示在頂部，而不是中心。據我所知GridBagLayout應該工作，但它集中了可用的單紅色jpanel。所有的佈局管理員都將它們集中在一起，但不是從上到下進行堆疊。
即使錨集合向北則面板仍將居中。你可以通過添加一個虛擬面板來填補餘下的空間。就個人而言，我會盡可能遠離GridBagLayout。
JFrame frame = new JFrame();
JPanel content = new JPanel();
content.setBorder(BorderFactory.createLineBorder(Color.red));
frame.setContentPane(content);
frame.getContentPane().setLayout(new GridBagLayout());
frame.setSize(400, 300);
for (int i = 0; i < 3; i++) {
JPanel panel = new JPanel();
panel.add(new JLabel("label1"));
panel.add(new JLabel("label2"));
panel.add(new JLabel("label3"));
panel.setBorder(BorderFactory.createLineBorder(Color.red));
GridBagConstraints con = new GridBagConstraints();
con.gridy = i;
con.gridx = 0;
con.anchor = GridBagConstraints.NORTHWEST;
con.ipady = 10;
frame.getContentPane().add(panel, con);
}
// dummy panel to use up the space (force others to top)
frame.getContentPane().add(
new JPanel(),
new GridBagConstraints(0, 3, 1, 1, 1, 1,
GridBagConstraints.NORTHWEST,
GridBagConstraints.VERTICAL, new Insets(0, 0, 0, 0), 0,
0));
frame.setVisible(true);
GroupLayout示例（我最喜歡的佈局管理器）。
JFrame frame = new JFrame();
JPanel content = new JPanel();
frame.setContentPane(content);
frame.getContentPane().setLayout(
new BoxLayout(content, BoxLayout.Y_AXIS));
frame.setSize(400, 300);
GroupLayout gLayout = new GroupLayout(content);
content.setLayout(gLayout);
ParallelGroup hGroup = gLayout.createParallelGroup();
gLayout.setHorizontalGroup(hGroup);
SequentialGroup vGroup = gLayout.createSequentialGroup();
gLayout.setVerticalGroup(vGroup);
for (int i = 0; i < 3; i++) {
JPanel panel = new JPanel();
panel.add(new JLabel("label1"));
panel.add(new JLabel("label2"));
panel.add(new JLabel("label3"));
panel.setBorder(BorderFactory.createLineBorder(Color.red));
hGroup.addComponent(panel);
vGroup.addComponent(panel, GroupLayout.PREFERRED_SIZE,
GroupLayout.PREFERRED_SIZE, GroupLayout.PREFERRED_SIZE);
vGroup.addGap(10);
}
frame.setVisible(true);
您可以使用垂直BoxLayout的，例如： http://www.java-tips.org/java-se-tips/javax.swing/how-to-use-swing-boxlayout.html
嘗試過，這確實得到了預期位置的第一個元素，但是當只有兩個元素時，下一個元素被展開佔據整個重新渲染的位置 – sasidhar 2012-03-12 21:27:33
嘗試將框佈局面板添加到具有邊框佈局的面板的北側。 – 2012-03-13 10:54:34
有相同的問題，使用Axis = y使用BoxLayout解決。感謝Wajdy – 2012-06-07 05:25:13
沒有人告訴我們，所有JComponent上必須是可見的，例如
從代碼
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.LineBorder;
public class AddComponentsAtRuntime {
private JFrame f;
private JPanel panel;
private JCheckBox checkValidate, checkReValidate, checkRepaint, checkPack;
public AddComponentsAtRuntime() {
f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
panel = new JPanel(new GridLayout(0, 1));
f.add(panel, "Center");
f.add(getCheckBoxPanel(), "South");
f.setLocation(200, 200);
f.pack();
f.setVisible(true);
}
private JPanel getCheckBoxPanel() {
checkValidate = new JCheckBox("validate");
checkValidate.setSelected(false);
checkReValidate = new JCheckBox("revalidate");
checkReValidate.setSelected(false);
checkRepaint = new JCheckBox("repaint");
checkRepaint.setSelected(false);
checkPack = new JCheckBox("pack");
checkPack.setSelected(false);
JButton addComp = new JButton("Add New One");
addComp.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
JPanel b = new JPanel(new GridLayout(0, 4));
b.setBackground(Color.red);
b.setBorder(new LineBorder(Color.black, 2));
//b.setPreferredSize(new Dimension(600, 20));
for (int i = 0; i < 4; i++) {
JLabel l = new JLabel("label" + i + 1);
b.add(l);
if (i == 2) {
l.setVisible(false);
}
}
panel.add(b);
makeChange();
System.out.println(" Components Count after Adds :" + panel.getComponentCount());
}
});
JButton removeComp = new JButton("Remove One");
removeComp.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
int count = panel.getComponentCount();
if (count > 0) {
panel.remove(0);
}
makeChange();
System.out.println(" Components Count after Removes :" + panel.getComponentCount());
}
});
JPanel panel2 = new JPanel();
panel2.add(checkValidate);
panel2.add(checkReValidate);
panel2.add(checkRepaint);
panel2.add(checkPack);
checkPack.setSelected(true);
panel2.add(addComp);
panel2.add(removeComp);
return panel2;
}
private void makeChange() {
if (checkValidate.isSelected()) {
panel.validate();
}
if (checkReValidate.isSelected()) {
panel.revalidate();
}
if (checkRepaint.isSelected()) {
panel.repaint();
}
if (checkPack.isSelected()) {
f.pack();
}
}
public static void main(String[] args) {
AddComponentsAtRuntime makingChanges = new AddComponentsAtRuntime();
}
}
你應該嘗試MigLayout，它很簡單但功能強大。下面我告訴miglayout增長元素，並填充所有可能的空間，然後在每個元素之後，我告訴它去一個新行（換行）。你可以找到MigLayout http://www.miglayout.com/頁中的實例和教程：
import net.miginfocom.swing.MigLayout;
public class PanelLearning extends JPanel {
public PanelLearning() {
setLayout(new MigLayout("", "[grow, fill]", ""));
for (int i = 0; i < 3; i++) {
JPanel panel = new JPanel();
panel.add(new JLabel("label1"));
panel.add(new JLabel("label2"));
panel.add(new JLabel("label3"));
panel.setBorder(BorderFactory.createLineBorder(Color.red));
add(panel, "span, wrap");
}
}
public static void main(String[] args) {
JFrame frame = new JFrame("Login");
frame.setVisible(true);
frame.setContentPane(new PanelLearning());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.pack();
}
}
我挺沒得到你meant.The什麼JPanel的內容是真正動態。什麼是適當的佈局管理器，這樣做？並將其從最外層的jpanel（帶有awt背景的jpanel）中添加到「JScrollPane」。所以'FlowLayout'不工作 – sasidhar 2012-03-12 21:16:47