Ich habe mein eigenes Closeable implementiertJTabbedPane (im Wesentlichen nach Rat vonHier - durch verlängernJTabbedPane und Überschreiben einiger Methoden und Aufrufen von setTabComponentAt (...)). Mit einer Ausnahme funktioniert es einwandfrei. Wenn zu viele Registerkarten in eine Zeile passen (wenn zwei oder mehr Registerkartenzeilen vorhanden sind), wird die Schaltfläche / das Symbol nicht rechts neben der Registerkarte ausgerichtet, sondern bleibt neben der Tab-Titel, der hässlich aussieht. Ich habe die Demo von Java-Tutorials ausprobiert und es leidet unter dem gleichen Problem.

Was ich möchte, ist, dass das Kreuz / Symbol immer ganz rechts ausgerichtet ist, aber der Text immer zur Mitte ausgerichtet ist. Kann dies durch einige Layout-Tricks erreicht werden? Hinweis: Ich möchte keine benutzerdefinierte implementierenTabbedPaneUI da dies zu anderen problemen führt.

AKTUALISIEREN Ich bin gezwungen, Java 6 zu verwenden

Der vollständige Code ist unten, führen Sie ihn einfach aus und fügen Sie 5 oder mehr Registerkarten hinzu.

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.net.URL;

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;


/**
 * CloseableTabbedPane is a tabbed pane with a close icon on the right side of all tabs making it possible to close a tab.
 * You can pass an instance of TabClosingListener to one of the constructors to react to tab closing.
 * 
 * @author WiR
 */
public class CloseableTabbedPane extends JTabbedPane {

    public static interface TabClosingListener {
        /**
         * @param aTabIndex the index of the tab that is about to be closed
         * @return true if the tab can be really closed
         */
        public boolean tabClosing(int aTabIndex);

        /**
         * @param aTabIndex the index of the tab that is about to be closed
         * @return true if the tab should be selected before closing
         */
        public boolean selectTabBeforeClosing(int aTabIndex);
    }

    private TabClosingListener tabClosingListener;
    private String iconFileName = "images/cross.gif";
    private String selectedIconFileName = "images/cross_selected.gif";

    private static Icon CLOSING_ICON;
    private static Icon CLOSING_ICON_SELECTED;

    private class PaintedCrossIcon implements Icon {

        int size = 10;

        @Override
        public void paintIcon(Component c, Graphics g, int x, int y) {
            g.drawLine(x, y, x + size, y + size);
            g.drawLine(x + size, y, x, y + size);
        }

        @Override
        public int getIconWidth() {
            return size;
        }

        @Override
        public int getIconHeight() {
            return size;
        }

    }

    public CloseableTabbedPane() {
        super();
    }

    public CloseableTabbedPane(TabClosingListener aTabClosingListener) {
        super();
        tabClosingListener = aTabClosingListener;
    }

    /**
     * Sets the file name of the closing icon along with the optional variant of the icon when the mouse is over the icon.
     */
    public void setClosingIconFileName(String aIconFileName, String aSelectedIconFileName) {
        iconFileName = aIconFileName;
        selectedIconFileName = aSelectedIconFileName;
    }

    /**
     * Makes the close button at the specified indes visible or invisible
     */
    public void setCloseButtonVisibleAt(int aIndex, boolean aVisible) {
        CloseButtonTab cbt = (CloseButtonTab) getTabComponentAt(aIndex);
        cbt.closingLabel.setVisible(aVisible);
    }

    @Override
    public void insertTab(String title, Icon icon, Component component, String tip, int index) {
        super.insertTab(title, icon, component, tip, index);
        setTabComponentAt(index, new CloseButtonTab(component, title, icon));
    }

    @Override
    public void setTitleAt(int index, String title) {
        super.setTitleAt(index, title);
        CloseButtonTab cbt = (CloseButtonTab) getTabComponentAt(index);
        cbt.label.setText(title);
    }

    @Override
    public void setIconAt(int index, Icon icon) {
        super.setIconAt(index, icon);
        CloseButtonTab cbt = (CloseButtonTab) getTabComponentAt(index);
        cbt.label.setIcon(icon);
    }

    @Override
    public void setComponentAt(int index, Component component) {
        CloseButtonTab cbt = (CloseButtonTab) getTabComponentAt(index);
        super.setComponentAt(index, component);
        cbt.tab = component;
    }

    //note: setToolTipTextAt(int) must NOT be overridden !

    private Icon getImageIcon(String aImageName) {
        URL imageUrl = CloseableTabbedPane.class.getClassLoader().getResource(aImageName);
        if (imageUrl == null) {
            return new PaintedCrossIcon();
        }
        ImageIcon result = new ImageIcon(imageUrl);
        if (result.getIconWidth() != -1) {
            return result;
        } else {
            return null;
        }
    }

    private class CloseButtonTab extends JPanel {
        private Component tab;
        private JLabel label;
        private JLabel closingLabel;

        public CloseButtonTab(Component aTab, String aTitle, Icon aIcon) {
            tab = aTab;
            setOpaque(false);
            setLayout(new GridBagLayout());
            setVisible(true);

            GridBagConstraints gbc = new GridBagConstraints();
            gbc.insets = new Insets(0, 0, 0, 5);

            label = new JLabel(aTitle);
            label.setIcon(aIcon);
            add(label, gbc);
            if (CLOSING_ICON == null) {
                CLOSING_ICON = getImageIcon(iconFileName);
                CLOSING_ICON_SELECTED = getImageIcon(selectedIconFileName);
            }
            closingLabel = new JLabel(CLOSING_ICON);
            closingLabel.addMouseListener(new MouseAdapter() {
                public void mouseClicked(MouseEvent e) {
                    JTabbedPane tabbedPane = (JTabbedPane) getParent().getParent();
                    int tabIndex = indexOfComponent(tab);
                    if (tabClosingListener != null) {
                        if (tabClosingListener.selectTabBeforeClosing(tabIndex)) {
                            tabbedPane.setSelectedIndex(tabIndex);
                        }
                        if (tabClosingListener.tabClosing(tabIndex)) {
                            tabbedPane.removeTabAt(tabIndex);
                        }
                    } else {
                        tabbedPane.removeTabAt(tabIndex);
                    }
                }

                @Override
                public void mouseEntered(MouseEvent e) {
                    if (CLOSING_ICON_SELECTED != null) {
                        closingLabel.setIcon(CLOSING_ICON_SELECTED);
                    }
                }

                @Override
                public void mouseExited(MouseEvent e) {
                    if (CLOSING_ICON_SELECTED != null) {
                        closingLabel.setIcon(CLOSING_ICON);
                    }
                }
            });
            gbc.insets = new Insets(0, 0, 0, 0);
            add(closingLabel, gbc);
        }
    }

    static int count = 0;

    /**
     * For testing purposes.
     * 
     */
    public static void main(String[] args) {

        final JTabbedPane tabbedPane = new CloseableTabbedPane();
        tabbedPane.addTab("test" + count, new JPanel());
        count++;
        JPanel mainPanel = new JPanel(new BorderLayout());
        mainPanel.add(tabbedPane, BorderLayout.CENTER);

        JButton addButton = new JButton("Add tab");
        addButton.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                tabbedPane.addTab("test" + count, new JPanel());
                count++;
            }
        });
        mainPanel.add(addButton, BorderLayout.SOUTH);

        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(700,  400);
        frame.getContentPane().add(mainPanel);
        frame.setVisible(true);
    }
}