Swing Menus and Toolbars - The Definitive Guide to Java Swing - page 194

// Borrows heavily from BasicMenuItemUI.getPath()
private MenuElement[] getPath() {
MenuSelectionManager menuSelectionManager =
MenuSelectionManager.defaultManager();
MenuElement oldPath[] = menuSelectionManager.getSelectedPath();
MenuElement newPath[];
int oldPathLength = oldPath.length;
if (oldPathLength == 0)
return new MenuElement[0];
Component parent = getParent();
if (oldPath[oldPathLength-1].getComponent() == parent) {
// Going deeper under the parent menu
newPath = new MenuElement[oldPathLength+1];
System.arraycopy(oldPath, 0, newPath, 0, oldPathLength);
newPath[oldPathLength] = this;
} else {
// Sibling/child menu item currently selected
int newPathPosition;
for (newPathPosition = oldPath.length-1; newPathPosition >= 0;
newPathPosition--) {
if (oldPath[newPathPosition].getComponent() == parent) {
break;
}
}
newPath = new MenuElement[newPathPosition+2];
System.arraycopy(oldPath, 0, newPath, 0, newPathPosition+1);
newPath[newPathPosition+1] = this;
}
return newPath;
}
}
■ Note The MouseInputListener defined in the init() method and the getPath() method borrow
heavily from the system BasicMenuUI class. Normally, the user interface delegate deals with what happens
when the mouse moves over a menu component. Because the JToggleButton isn't a predefined menu
component, its UI class doesn't deal with it. For better modularity, these two methods should be moved into
an extended ToggleButtonUI .
Once you've created this JToggleButtonMenuItem class, you can use it like any other
menu item:
JToggleButtonMenuItem toggleItem = new JToggleButtonMenuItem("Balloon Help");
editMenu.add(toggleItem);