问题
没有空白区域的GUI显得"拥挤"。如何在不明确设置组件的位置或大小的情况下提供空白区域？
#1 热门回答(95 赞)
使用各种LayoutManagersone可以提供各种组件之间的间距。
1.)BorderLayout：
- 重载的构造函数：BorderLayout(int horizontalGap，int verticalGap)
- Getter和setter方法For Horizontal Spacing：BorderLayout.getHgap()和BorderLayout.setHgap(int hgap)For Vertical Spacing：BorderLayout.getVgap()和BorderLayout.setVgap()
2. 2.)FlowLayout：
- 重载的构造函数：FlowLayout(int align，int hgap，int vgap)
- Getter和setter方法For Horizontal Spacing：FlowLayout.getHgap()和FlowLayout.setHgap(int hgap)For Vertical Spacing：FlowLayout.getVgap()和FlowLayout.setVgap()
3.)GridLayout：
- 重载的构造函数：GridLayout(int rows，int columns，int hgap，int vgap)
- Getter和setter方法For Horizontal Spacing：GridLayout.getHgap()和GridLayout.setHgap(int hgap)For Vertical Spacing：GridLayout.getVgap()和GridLayout.setVgap()
4.)GridBagLayout：
5.)CardLayout(示例)：
CardLayout(int hGap, int vGap)
##显示所有构造函数的示例：
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class LayoutExample {
private final int hGap = 5;
private final int vGap = 5;
private String[] borderConstraints = {
BorderLayout.PAGE_START,
BorderLayout.LINE_START,
BorderLayout.CENTER,
BorderLayout.LINE_END,
BorderLayout.PAGE_END
};
private JButton[] buttons;
private GridBagConstraints gbc;
private JPanel borderPanel;
private JPanel flowPanel;
private JPanel gridPanel;
private JPanel gridBagPanel;
private JPanel cardPanel;
public LayoutExample() {
buttons = new JButton[16];
gbc = new GridBagConstraints();
gbc.anchor = GridBagConstraints.FIRST_LINE_START;
gbc.insets = new Insets(hGap, vGap, hGap, vGap);
}
private void displayGUI() {
JFrame frame = new JFrame("Layout Example");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
JPanel contentPane = new JPanel(
new GridLayout(0, 1, hGap, vGap));
contentPane.setBorder(
BorderFactory.createEmptyBorder(hGap, vGap, hGap, vGap));
borderPanel = new JPanel(new BorderLayout(hGap, vGap));
borderPanel.setBorder(
BorderFactory.createTitledBorder("BorderLayout"));
borderPanel.setOpaque(true);
borderPanel.setBackground(Color.WHITE);
for (int i = 0; i < 5; i++) {
buttons[i] = new JButton(borderConstraints[i]);
borderPanel.add(buttons[i], borderConstraints[i]);
}
contentPane.add(borderPanel);
flowPanel = new JPanel(new FlowLayout(
FlowLayout.CENTER, hGap, vGap));
flowPanel.setBorder(
BorderFactory.createTitledBorder("FlowLayout"));
flowPanel.setOpaque(true);
flowPanel.setBackground(Color.WHITE);
for (int i = 5; i < 8; i++) {
buttons[i] = new JButton(Integer.toString(i));
flowPanel.add(buttons[i]);
}
contentPane.add(flowPanel);
gridPanel = new JPanel(new GridLayout(2, 2, hGap, vGap));
gridPanel.setBorder(
BorderFactory.createTitledBorder("GridLayout"));
gridPanel.setOpaque(true);
gridPanel.setBackground(Color.WHITE);
for (int i = 8; i < 12; i++) {
buttons[i] = new JButton(Integer.toString(i));
gridPanel.add(buttons[i]);
}
contentPane.add(gridPanel);
gridBagPanel = new JPanel(new GridBagLayout());
gridBagPanel.setBorder(
BorderFactory.createTitledBorder("GridBagLayout"));
gridBagPanel.setOpaque(true);
gridBagPanel.setBackground(Color.WHITE);
buttons[12] = new JButton(Integer.toString(12));
addComp(gridBagPanel, buttons[12], 0, 0, 1, 1
, GridBagConstraints.BOTH, 0.33, 0.5);
buttons[13] = new JButton(Integer.toString(13));
addComp(gridBagPanel, buttons[13], 1, 0, 1, 1
, GridBagConstraints.BOTH, 0.33, 0.5);
buttons[14] = new JButton(Integer.toString(14));
addComp(gridBagPanel, buttons[14], 0, 1, 2, 1
, GridBagConstraints.BOTH, 0.66, 0.5);
buttons[15] = new JButton(Integer.toString(15));
addComp(gridBagPanel, buttons[15], 2, 0, 1, 2
, GridBagConstraints.BOTH, 0.33, 1.0);
contentPane.add(gridBagPanel);
cardPanel = new JPanel(new CardLayout(hGap, vGap));
cardPanel.setBorder(
BorderFactory.createTitledBorder("CardLayout"));
cardPanel.setOpaque(true);
cardPanel.setBackground(Color.WHITE);
cardPanel.add(getPanel(Color.BLUE));
cardPanel.add(getPanel(Color.GREEN));
contentPane.add(cardPanel);
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private JPanel getPanel(Color bColor) {
JPanel panel = new JPanel(new FlowLayout(
FlowLayout.CENTER, hGap, vGap));
panel.setOpaque(true);
panel.setBackground(bColor.darker().darker());
JButton swapperButton = new JButton("Next");
swapperButton.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent ae) {
CardLayout cardLayout = (CardLayout) cardPanel.getLayout();
cardLayout.next(cardPanel);
}
});
panel.add(swapperButton);
return panel;
}
private void addComp(JPanel panel, JComponent comp
, int x, int y, int gWidth
, int gHeight, int fill
, double weightx, double weighty) {
gbc.gridx = x;
gbc.gridy = y;
gbc.gridwidth = gWidth;
gbc.gridheight = gHeight;
gbc.fill = fill;
gbc.weightx = weightx;
gbc.weighty = weighty;
panel.add(comp, gbc);
}
public static void main(String[] args) {
Runnable runnable = new Runnable(){
@Override
public void run() {
new LayoutExample().displayGUI();
}
};
EventQueue.invokeLater(runnable);
}
}
##输出：
#2 热门回答(56 赞)
Swing GUI中有许多方法可以提供组件之间的分离，以及组件周围的空白区域：
- JToolBar有方法addSeparator()和addSeparator(Dimension)。
- JMenu使用更适合菜单的间距组件，可通过addSeparator()获得。
但更一般地说，请看：
- 可以在布局构造函数中定义的间距。
- 边界。
下面是使用布局分隔符hGap和vGap值和边框(特别是anEmptyBorder)来提供'白色'(实际显示为红色以使其非常明显)空间的示例。调整微调器以查看结果。
import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
import javax.swing.event.*;
public class WhiteSpace {
private JPanel gui = null;
private BorderLayout mainLayout;
private FlowLayout buttonLayout;
private EmptyBorder border;
public Container getGui() {
if (gui==null) {
mainLayout = new BorderLayout(0,0);
gui = new JPanel(mainLayout);
gui.setBackground(Color.RED);
border = new EmptyBorder(0,0,0,0);
JTree tree = new JTree();
tree.setVisibleRowCount(10);
for (int ii = tree.getRowCount(); ii>-1; ii--) {
tree.expandRow(ii);
}
gui.add(new JScrollPane(
tree,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_NEVER),
BorderLayout.LINE_START);
gui.add(new JScrollPane(new JTextArea(10,30)));
buttonLayout = new FlowLayout(FlowLayout.CENTER,0,0);
JPanel buttonPanel = new JPanel(buttonLayout);
gui.add(buttonPanel, BorderLayout.PAGE_START);
buttonPanel.add(new JLabel("H Gap"));
final JSpinner hSpinner =
new JSpinner(new SpinnerNumberModel(0,0,15,1));
buttonPanel.add(hSpinner);
buttonPanel.add(new JLabel("V Gap"));
final JSpinner vSpinner =
new JSpinner(new SpinnerNumberModel(0,0,15,1));
buttonPanel.add(vSpinner);
buttonPanel.add(new JLabel("H Border"));
final JSpinner hBorderSpinner =
new JSpinner(new SpinnerNumberModel(0,0,15,1));
buttonPanel.add(hBorderSpinner);
buttonPanel.add(new JLabel("V Border"));
final JSpinner vBorderSpinner =
new JSpinner(new SpinnerNumberModel(0,0,15,1));
buttonPanel.add(vBorderSpinner);
ChangeListener changeListener = new ChangeListener() {
@Override
public void stateChanged(ChangeEvent e) {
int hGap = ((Integer)hSpinner.getValue()).intValue();
int vGap = ((Integer)vSpinner.getValue()).intValue();
int hBorder = ((Integer)hBorderSpinner.getValue()).intValue();
int vBorder = ((Integer)vBorderSpinner.getValue()).intValue();
adjustWhiteSpace(hGap,vGap,hBorder,vBorder);
}
};
hSpinner.addChangeListener(changeListener);
vSpinner.addChangeListener(changeListener);
hBorderSpinner.addChangeListener(changeListener);
vBorderSpinner.addChangeListener(changeListener);
}
return gui;
}
private void adjustWhiteSpace(int hGap, int vGap, int hBorder, int vBorder) {
mainLayout.setHgap(hGap);
mainLayout.setVgap(vGap);
buttonLayout.setHgap(hGap);
gui.setBorder(new EmptyBorder(vBorder,hBorder,vBorder,hBorder));
Container c = gui.getTopLevelAncestor();
if (c instanceof Window) {
Window w = (Window)c;
w.pack();
}
}
public static void main(String[] args) {
Runnable r = new Runnable() {
@Override
public void run() {
WhiteSpace ws = new WhiteSpace();
// the GUI as seen by the user (without frame)
Container gui = ws.getGui();
JFrame f = new JFrame("White (OK Red) Space");
f.add(gui);
// Ensures JVM closes after frame(s) closed and
// all non-daemon threads are finished
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
// See http://stackoverflow.com/a/7143398/418556 for demo.
f.setLocationByPlatform(true);
// ensures the frame is the minimum size it needs to be
// in order display the components within it
f.setResizable(false);
f.pack();
// should be done last, to avoid flickering, moving,
// resizing artifacts.
f.setVisible(true);
}
};
SwingUtilities.invokeLater(r);
}
}
#3 热门回答(18 赞)
当你使用BoxLayout,Box.createVerticalGlue()方法可以帮你制作一些空白区域。
另一种方法是BorderFactory.createEmptyBorder(int top, int left, int bottom, int right)。它可以帮助你在组件周围创建一些空白区域。
感谢Andrew Thompson的提醒。我最近几天修改了BoxLayout，我发现Box.createVerticalGlue()可以根据面板的大小添加一些空白区域，你无法设置白色空间长度的显式像素值。但是，Box.createVerticalStrut()可以做到这一点。这是一个MCTaRE并显示这两种方法的效果。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.event.*;
public class WhiteSpace extends JFrame{
static WhiteSpace whiteSpace;
DemoPanel demoPanel;
boolean withGlue;
JSpinner spinner;
public WhiteSpace(){
initialWindow();
demoPanel = new DemoPanel();
ActionPanel actionPanel = new ActionPanel();
setLayout(new BorderLayout());
getContentPane().add(actionPanel,BorderLayout.NORTH);
getContentPane().add(demoPanel,BorderLayout.CENTER);
setVisible(true);
}
public void initialWindow(){
setSize(220, 300);
setTitle("White Space");
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
//Show the window in the middle of the screen
}
/**
* @param args
*/
public static void main(String[] args) {
Runnable runnable = new Runnable() {
@Override
public void run() {
whiteSpace = new WhiteSpace();
}
};
SwingUtilities.invokeLater(runnable);
}
class DemoPanel extends JPanel{
//Show the vertical white space between label1 and label2
JLabel label1;
JLabel label2;
public void initialDemoPanel(){
setBorder(BorderFactory.createTitledBorder(getBorder(), "DemoPanel", TitledBorder.LEADING, TitledBorder.TOP, new Font("Default",Font.PLAIN,10), Color.gray));
setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
label1 = new JLabel("This is first line");
label2 = new JLabel("This is second line");
}
public DemoPanel(){
initialDemoPanel();
add(label1);
if(withGlue){
add(Box.createVerticalGlue());
}
add(label2);
}
public DemoPanel(int strutValue){
initialDemoPanel();
add(label1);
add(Box.createVerticalStrut(strutValue));
add(label2);
}
}
class ActionPanel extends JPanel{
public ActionPanel(){
setBorder(BorderFactory.createTitledBorder(getBorder(), "ActionPanel", TitledBorder.LEADING, TitledBorder.TOP, new Font("Default",Font.PLAIN,10), Color.gray));
setLayout(new BoxLayout(this,BoxLayout.X_AXIS));
JRadioButton glueButton = new JRadioButton("With Glue");
glueButton.addActionListener(new glueButtonListener());
add(glueButton);
add(Box.createHorizontalStrut(10));
//To create horizontal white space
JLabel strutLabel = new JLabel("Strut Value");
add(strutLabel);
spinner = new JSpinner(new SpinnerNumberModel(0,0,50,1));
spinner.addChangeListener(new spinnerListener());
add(spinner);
//public SpinnerNumberModel(Number value,Comparable minimum,Comparable maximum,Number stepSize)
}
}
class glueButtonListener implements ActionListener{
@Override
public void actionPerformed(ActionEvent e) {
spinner.setValue(new Integer(0));
withGlue = (withGlue == true ? false:true);
whiteSpace.getContentPane().remove(demoPanel);
demoPanel = new DemoPanel();
whiteSpace.getContentPane().add(demoPanel,BorderLayout.CENTER);
whiteSpace.getContentPane().validate();
}
}
class spinnerListener implements ChangeListener{
@Override
public void stateChanged(ChangeEvent e) {
int strutValue = (Integer) spinner.getValue();
whiteSpace.getContentPane().remove(demoPanel);
demoPanel = new DemoPanel(strutValue);
whiteSpace.getContentPane().add(demoPanel,BorderLayout.CENTER);
whiteSpace.getContentPane().validate();
}
}
}
Box.createHorizontalGlue()和Box.createHorizontalStrut(int height)也可以使用。此外，Box.createRigidArea(Dimension d)也有能力创造空白。