如何在不使用 HTML 的情况下向 JLabel 添加换行符

Question

How can I add a new line to a JLabel ? I know if I use simple HTML, it will work. But if I use HTML, JLabel is not showing the font which embedded with the application. I am embedding the font using the method - createFont() and using JLabel.setFont() for applying the font.

Answer 1

SwingX supports multiline labels:

   JXLabel label = new JXLabel();
   label.setLineWrap(true);

Answer 2

I don't think there is direct(and easy) way of doing JLabel with multiple lines without recurring to HTML. You can use JTextArea instead.

JTextArea textArea = new JTextArea();
textArea.setEditable(false);
textArea.setLineWrap(true);
textArea.setOpaque(false);
textArea.setBorder(BorderFactory.createEmptyBorder());
add(textArea, BorderLayout.CENTER);

It should look almost the same. If you have different fonts for different components, you can add the following line to ensure that the font of JTextArea is the same with JLabel

textArea.setFont(UIManager.getFont("Label.font"));

Hope this helps.

Answer 3

I am Embedding the font using the method - createFont() ) and using JLabel.setFont() for applying the font.

Instead try setting it in the HTML, as shown here .

Answer 4

JLabel is not originally intended for multiline text, from what I recall. You would need to override the various rendering methods to do the text line splitting manually.

Perhaps you should rather use a non-editable JTextArea if you want multiline labels.

Answer 5

Most of the following code is taken from BasicLabelUI and/or WindowsLabelUI but I added code to make it work with multiple lines. This was the minimum amount of copied code I could get to work. You can set the separator character between the lines with setSeparator or by changing the default on the instantiation of LinesAndIndex. I have not done extensive testing on this but it works for me so far. When using HTML the mnemonic did not work so I created this. If you have a better way to accomplish this please correct the code.

    import com.sun.java.swing.plaf.windows.WindowsLabelUI;
    import com.sun.java.swing.plaf.windows.WindowsLookAndFeel;
    import java.awt.Color;
    import java.awt.FontMetrics;
    import java.awt.Graphics;
    import java.awt.Insets;
    import java.awt.Rectangle;
    import java.util.ArrayList;
    import java.util.List;
    import javax.swing.Icon;
    import javax.swing.JComponent;
    import javax.swing.JLabel;
    import javax.swing.UIManager;
    import javax.swing.plaf.LabelUI;
    import javax.swing.plaf.basic.BasicGraphicsUtils;
    import javax.swing.plaf.basic.BasicHTML;
    import javax.swing.text.View;

    public class MultiLineLabelUI extends WindowsLabelUI {
        private static MultiLineLabelUI multiLineLabelUI;
        private LinesAndIndex lai = new LinesAndIndex(',');
        private Rectangle paintIconR = new Rectangle();
        private Rectangle paintTextR = new Rectangle();
        public static LabelUI createUI(JComponent c) {
            if (multiLineLabelUI == null) {
                multiLineLabelUI = new MultiLineLabelUI();
            }
            return multiLineLabelUI;
        }
        private int getBaseline(JComponent c, int y, int ascent, int w, int h) {
            View view = (View) c.getClientProperty(BasicHTML.propertyKey);
            if (view != null) {
                int baseline = BasicHTML.getHTMLBaseline(view, w, h);
                if (baseline < 0) {
                    return baseline;
                }
                return y + baseline;
            }
            return y + ascent;
        }
        public char getSeparator() {
            return lai.getSeparator();
        }
        public void setSeparator(char ch) {
            lai.setSeparator(ch);
        }
        private String layout(JLabel label, FontMetrics fm,
                int width, int height, int lineCnt, int curLine, String text) {
            Insets insets = label.getInsets(null);
            Icon icon = (label.isEnabled()) ? label.getIcon()
                    : label.getDisabledIcon();
            Rectangle paintViewR = new Rectangle();
            paintViewR.width = width - (insets.left + insets.right);
            paintViewR.height = (height - (insets.top + insets.bottom)) / lineCnt;
            paintViewR.x = insets.left;
            paintViewR.y = insets.top + (paintViewR.height * curLine);
            paintIconR.x = 0;
            paintIconR.y = 0;
            paintIconR.width = 0;
            paintIconR.height = 0;
            paintTextR.x = 0;
            paintTextR.y = 0;
            paintTextR.width = 0;
            paintTextR.height = 0;
            return layoutCL(label, fm, text, icon, paintViewR, paintIconR,
                    paintTextR);
        }
        protected void paintEnabledText(JLabel l, Graphics g,
                String s, int textX, int textY, int curLine) {
            int mnemonicIndex = lai.getMnemonicIndex();
            // W2K Feature: Check to see if the Underscore should be rendered.
            if (WindowsLookAndFeel.isMnemonicHidden() == true) {
                mnemonicIndex = -1;
            }
            if (curLine != lai.getMnemonicLineIndex()) {
                mnemonicIndex = -1;
            }

            g.setColor(l.getForeground());
            BasicGraphicsUtils.drawStringUnderlineCharAt(g, s, mnemonicIndex,
                    textX, textY);
        }
        protected void paintDisabledText(JLabel l, Graphics g,
                String s, int textX, int textY, int curLine) {
            int mnemonicIndex = lai.getMnemonicIndex();
            // W2K Feature: Check to see if the Underscore should be rendered.
            if (WindowsLookAndFeel.isMnemonicHidden() == true) {
                mnemonicIndex = -1;
            }
            if (curLine != lai.getMnemonicLineIndex()) {
                mnemonicIndex = -1;
            }
            if (UIManager.getColor("Label.disabledForeground") instanceof Color
                    && UIManager.getColor("Label.disabledShadow") instanceof Color) {
                g.setColor(UIManager.getColor("Label.disabledShadow"));
                BasicGraphicsUtils.drawStringUnderlineCharAt(g, s, mnemonicIndex,
                        textX + 1, textY + 1);
                g.setColor(UIManager.getColor("Label.disabledForeground"));
                BasicGraphicsUtils.drawStringUnderlineCharAt(g, s, mnemonicIndex,
                        textX, textY);
            } else {
                Color background = l.getBackground();
                g.setColor(background.brighter());
                BasicGraphicsUtils.drawStringUnderlineCharAt(g, s, mnemonicIndex,
                        textX + 1, textY + 1);
                g.setColor(background.darker());
                BasicGraphicsUtils.drawStringUnderlineCharAt(g, s, mnemonicIndex,
                        textX, textY);
            }
        }
        @Override
        public void paint(Graphics g, JComponent c) {
            JLabel label = (JLabel) c;
            String text = label.getText();
            Icon icon = (label.isEnabled())
                    ? label.getIcon()
                    : label.getDisabledIcon();

            if ((icon == null) && (text == null)) {
                return;
            }
            char mnemonic = (char) label.getDisplayedMnemonic();
            lai.splitText(text, mnemonic);
            List<String> lines = lai.getLines();

            FontMetrics fm = label.getFontMetrics(g.getFont());
            String[] clippedText = new String[lines.size()];
            for (int i = 0; i < lines.size(); i++) {
                clippedText[i] = layout(label, fm, c.getWidth(), c.getHeight(),
                        lines.size(), i, lines.get(i));

                if (icon != null && i == 0) {
                    icon.paintIcon(c, g, paintIconR.x, paintIconR.y);
                }

                if (text != null) {
                    int textX = paintTextR.x;
                    int textY = paintTextR.y + fm.getAscent();

                    if (label.isEnabled()) {
                        paintEnabledText(label, g, clippedText[i], textX,
                                textY, i);
                    } else {
                        paintDisabledText(label, g, clippedText[i], textX,
                                textY, i);
                    }
                }
            }
        }
        @Override
        public int getBaseline(JComponent c, int width, int height) {
            super.getBaseline(c, width, height);
            JLabel label = (JLabel) c;
            String text = label.getText();
            if (text == null || "".equals(text) || label.getFont() == null) {
                return -1;
            }
            char mnemonic = (char) label.getDisplayedMnemonic();
            lai.splitText(text, mnemonic);
            List<String> lines = lai.getLines();
            FontMetrics fm = label.getFontMetrics(label.getFont());
            String[] clippedText = new String[lines.size()];
            for (int i = 0; i < lines.size(); i++) {
                clippedText[i] = layout(label, fm, width, height, lines.size(), i,
                        lines.get(i));
            }
            return getBaseline(label, paintTextR.y, fm.getAscent(),
                    paintTextR.width, paintTextR.height);
        }

        private static class LinesAndIndex {
            private char sep;
            private List<String> lines;
            private int mnemonicLineIndex;
            private int mnemonicIndex;
            LinesAndIndex(char sep) {
                mnemonicLineIndex = -1;
                mnemonicIndex = -1;
                lines = new ArrayList<String>();
                this.sep = sep;
            }
            public char getSeparator() {
                return sep;
            }
            public void setSeparator(char sep) {
                this.sep = sep;
            }
            public List<String> getLines() {
                return lines;
            }
            public int getMnemonicLineIndex() {
                return mnemonicLineIndex;
            }
            public int getMnemonicIndex() {
                return mnemonicIndex;
            }
            public void splitText(String text, char mnemonic) {
                if (text == null) {
                    return;
                }
                lines.clear();
                mnemonicLineIndex = -1;
                mnemonicIndex = -1;
                char um = Character.toUpperCase(mnemonic);
                char lm = Character.toLowerCase(mnemonic);
                int umi = Integer.MAX_VALUE;
                int lmi = Integer.MAX_VALUE;
                int umli = -1;
                int lmli = -1;
                for (int i = 0, j = 0, k = 0; i < text.length(); i++) {
                    if (text.charAt(i) == sep) {
                        lines.add(text.substring(j, i));
                        j = i + 1;
                        k++;
                    } else if (text.charAt(i) == um) {
                        if (umi == Integer.MAX_VALUE) {
                            umi = i - j;
                            umli = k;
                        }
                    } else if (text.charAt(i) == lm) {
                        if (lmi == Integer.MAX_VALUE) {
                            lmi = i - j;
                            lmli = k;
                        }
                    }
                    if (i == text.length() - 1) {
                        lines.add(text.substring(j, i + 1));
                    }
                }
                mnemonicLineIndex = (lmi < umi) ? lmli : umli;
                mnemonicIndex = (lmi < umi) ? lmi : umi;
            }
        }

    }

Answer 6

1) if you want to Multiline JComponents without using JLabel, then you have to look for TextComponent as are JTextArea, JTextPane, JEditorPane, if should't be editable then myTextComponent#setEditable(false);

2) I never see problem with Html & Font & Color in Swing, for example:

import java.awt.Color;
import java.awt.Font;
import javax.swing.*;

public class ButtonFg extends JFrame {

    private static final long serialVersionUID = 1L;

    public ButtonFg() {
        JButton button = new JButton("<html> - myText <br>"
                + " - myText <br>"
                + " - myText <br>"
                + " - myText </html>");
        button.setForeground(Color.blue);
        button.setFont(new Font("Serif", Font.BOLD, 28));
        button.setFocusPainted(false);
        add(button);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocation(150, 150);
        pack();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new ButtonFg().setVisible(true);
            }
        });
    }
}