在Swing GUI中提供空白区域

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 horizo​​ntalGap,int verticalGap)
  • Getter和setter方法For Horizo​​ntal 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 Horizo​​ntal 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 Horizo​​ntal Spacing:GridLayout.getHgap()和GridLayout.setHgap(int hgap)For Vertical Spacing:GridLayout.getVgap()和GridLayout.setVgap()

4.)GridBagLayout:

GridBagConstraints.insets

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:

LAYOUTIMAGE


#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hGapvGap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。

With no GUI white space

With GUI white space

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。

enter image description here

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()Box.createHorizontalStrut(int height)也可以使用。此外,Box.createRigidArea(Dimension d)也有能力创造空白。