javax.swing.Action has a defined key used for storing a mnemonic to use with the action when presented as e.g. a menu item.

Unfortunately it does not permit you to set the displayed mnemonic index (which capability was added to Swing in 1.4). Consider an action "Save All" for which you would like the mnemonic 'A' at index 5. You would like it to display as "Save _A_ll" but it will actually display as "S_a_ve All" which is uglier.

There are also cases involving languages which do not use the Latin script that you need to explicit set the displayed index. For example, on a JMenuItem with the name rendered as Cyrillic "PHayl" (i.e. "File") you may wish to set a mnemonic using keystroke 'F' and place it at index 0 on the phi character. This is possible using JMenuItem directly, but not by creating an Action and calling JMenu.add(Action).
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