I'm encountering a strange Swing problem on basic nested JTabbedPane, and I wonder if you know what is happening.

Wheel scrolling is added to tabbedPanes and all is fine when tabs are on top of panes. But behavior doesn't work has expected when tab placement is on bottom or on left/right, it's the parent tabbedPane that is scrolled instead of the wheeled tabbedPane.

Have you encountered this problem already and have you thought about a fix?

Many thanks.

I made some debugging, it appears the e.getSource() of MouseWheelListener does not return the wheeled tabbedPane which is on SwingConstants.BOTTOM/LEFT/RIGHT, instead it returns the parent tabbedPane.

Here is the animated Gif of the problem:

• the two tabs on top are fine with tabPlacement on default (SwingConstants.TOP)
• the tabs on the left and on the bottom are scrolling their parents.

Gif Imgur: parent tabbedPane is changing when nested left/bottom tabbedPane is wheel-scrolled

Code

/**
 * Mousewheel allows to navigate to next/previous tab.
 */
public class TabbedPaneMouseWheelScroller implements MouseWheelListener {
    
    /**
     * Log4j logger sent to view.
     */
    private static final Logger LOGGER = Logger.getRootLogger();
    
    @Override
    public void mouseWheelMoved(MouseWheelEvent e) {
        
        JTabbedPane tabPane = (JTabbedPane) e.getSource();

        int dir = -e.getWheelRotation();
        int selIndex = tabPane.getSelectedIndex();
        int maxIndex = tabPane.getTabCount() - 1;
        
        if ((selIndex == 0 && dir < 0) || (selIndex == maxIndex && dir > 0)) {
            
            selIndex = maxIndex - selIndex;
            
        } else {
            
            selIndex += dir;
        }
        
        if (0 <= selIndex && selIndex < tabPane.getTabCount()) {
            
            // Fix #54575: NullPointerException on setSelectedIndex()
            try {
                tabPane.setSelectedIndex(selIndex);
            } catch (NullPointerException err) {
                LOGGER.error(err, err);
            }
        }
    }
}

ClassCastException when clicking on the spinner's arrow button.

 java.lang.ClassCastException: class java.lang.Double cannot be cast to class java.lang.Long (java.lang.Double and java.lang.Long are in module java.base of loader 'bootstrap')
   at example.MainPanel$2.stringToValue(MainPanel.java:80)
   at java.desktop/javax.swing.JFormattedTextField.commitEdit(JFormattedTextField.java:563)

Even if you enter the enter key in JTextPane of SimpleSyntaxHighlight/src/java/example/MainPanel.java, it is converted to white space and line break is not possible.

• ListCellItemCheckBoxes
• When the range selection area becomes a straight line with area 0, the selected state of JList cell items is canceled

Even if you cancel the dragging of tabs by pressing ESC or right-clicking the mouse, the tabs will still be displayed in the tab area if the debug display is enabled.

TabTitleAlignment: Switching between TOP and LEFT in the tab layout of JTabbedPane is reversed

paano gawin yung minute reminder using java swing? for example may inventory system ka tapos low qty na yung isang product mo dahil nabawasan ito tapos bigla may mag alert message na low stock na yung product mag snooze yon.

１０何年前から、Java Swing Tips をお世話になっております。

参加していたプロジェクトで Swing を使用することになり、ネットで検索したら　https://ateraimemo.com/Swing.html
に辿り着きました。当時（今でも）Swing が人気がなく、ちゃんと Swing のことを紹介するサイトはあんまりなかったですが、そのまま実行できるサンプルコードまであるサイトには、本当に感動しました。
おかげさまでプロジェクトが無事終了しましたが、Swing に対し興味を持ちました。以来、ちょっとしたツールを作るなどの時には、必ず　Java Swing Tips　に来て、参考になるのもがないかと。来るたびに思うですが、Swing のことで１０何年も更新し続けるのは、本当に素晴らしいです！心から感謝しています。本当にありがとうございます。

Swing は本当に使える物なのに、全然人気がないですね。
私は Swing 大好きな、時々遊びに来ますので、どうか続けてください。

よろしくお願いします。

• DnDTabbedPane
• https://github.com/aterai/java-swing-tips/blob/master/DnDTabbedPane/src/java/example/MainPanel.java
• OpenJDK Runtime Environment Corretto-8.332.08.1 (build 1.8.0_332-b08)
• Windows 10 Pro 21H2 19044.1706

When a tab with a tab component set using JTabbedPane#setTabComponentAt(int idx, Component c) is started to move by dragging the mouse, the tab component disappears.

This is not a problem with your class as written, but SwingUtilities.paintComponent() behaves in a way that can cause problems if small modifications are made.

I modified DnDTabbedPane so that the title of the tab is a Component and not a simple string. In my case, this Component consists of a JLabel and a JButton.

In initGlassPane(), SwingUtilities.paintComponent() is used to create the ghost image to drag around. For reasons I do not understand (Swing internals), the call to paintComponent() seems to change the ownership of the tab's Component -- or that is my guess. The fix is to duplicate the result of the call to getTabComponentAt(dragTabIndex) and feed that duplicate to paintComponent(). Exactly how this duplication is done will depend depend on the contents of the situation, so I can't offer a general fix.

How can dinamically selectedItem or selectedIndex in DropdownTableComboBox project from outside class.?
Thank you in advance

厉害

• CheckedComboBox
• https://github.com/aterai/java-swing-tips/blob/master/CheckedComboBox/src/java/example/MainPanel.java
• Ubuntu 20.04.2 LTS
• OpenJDK Runtime Environment AdoptOpenJDK-11.0.11+9 (build 11.0.11+9)

Rendering of the drop-down list with the check box opened from JComboBox becomes unstable on Ubuntu environment.
It does not reproduce in Windows 10 + AdoptOpenJDK-11.0.11+9 environment.